HomeMy WebLinkAboutIsland-Wide Quality Report 2018 (PDF) 1
Technical Memorandum
FINAL
Water Quality Monitoring and Assessment of the
Nantucket Island-Wide Estuaries and Salt Ponds
Update 2018
To:
Town of Nantucket
Natural Resources Department
2 Bathing Beach Road
Nantucket, MA 02554
From:
Brian Howes Ph.D. and Roland Samimy Ph.D.
Coastal Systems Program
School of Marine Science and Technology (SMAST)
University of Massachusetts-Dartmouth
706 South Rodney French Blvd.
New Bedford, MA 02744
June 2019
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Executive Summary
Water Quality Monitoring and Assessment of the
Nantucket Island-Wide Estuaries and Salt Ponds
Update 2018
As in previous years, this annual Technical Memorandum summarizes the water quality
monitoring results of the estuarine sampling undertaken through the ongoing Nantucket Island-
wide Water Quality Monitoring Program. The program is multi-year collaboration between the
Town of Nantucket Natural Resources Department and the Coastal Systems Program within the
University of Massachusetts-Dartmouth, School for Marine Science and Technology. Water
sample collection and analysis has been undertaken according to specific protocols developed at
the outset of the monitoring first undertaken in 2010 such that year to year results would be
cross comparable from one Nantucket estuary to another but also, so that Nantucket results
would also be cross comparable to water quality data collected from other programs managed by
the Coastal Systems Program (e.g. Cape Cod monitoring programs as well as Martha's Vineyard
Island-wide monitoring program). The 2018 summary memo is focused specifically on the
following: 1) Water Quality Results for Nantucket Harbor, Madaket Harbor, Long Pond,
Hummock Pond, Miacomet Pond, Sesachacha Pond, Polpis Harbor Streams and Oyster
Aquaculture Potential Sites, 2) Trophic State - Water Quality/Eutrophication Status and trends
and 3) Recommendations for Future Monitoring.
The goals of the monitoring program remain unchanged from previous years, primarily
to:
1. determine the present (2018) ecological health of each of the main salt ponds and
estuaries within the Town of Nantucket,
2. gauge (as historical data allows, 2010-2018) the decline or recovery of various
salt ponds and embayments over the long-term (also part of TMDL compliance),
and
3. provide the foundation (and context) for development of potential alternatives for
nutrient and resource management and quantitative measures of success.
Point (3) is critical for restoration planning should a system be found to be
impaired or trending toward impairment, which requires targeted management
actions for restoration or a system is improving due to Town actions which then
should be improved/enhanced.
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As was the case in 2010, 2012 - 2017 sampling efforts, the 2018 sampling program
focused on the summer/early fall months (June - September) as this time frame is
typically representative of worst case water quality conditions and the basis for habitat
management decisions. Samples collected in 2018 were obtained from the same
sampling station locations and the same depths as in previous years to maximize cross
comparability and to gauge temporal changes. It should be noted that the Town of
Nantucket did undertake water quality monitoring in 2011, however, those samples were
analyzed by a lab other than the Coastal Systems Analytical Facility at the UMASS
School for Marine Science and Technology and data was presented in the report on the
2012 monitoring effort.
The Town of Nantucket has been working for decades to protect and more recently
restore its estuaries and their aquatic resources. At present and based on the 2010 -
2018 water quality database developed under the Island-wide unified water quality
monitoring program, activities to lower nitrogen enrichment and its negative impacts to
water and habitat quality have been planned and implementation is ongoing in 4
estuarine systems: Nantucket Harbor (jetties and sewers), Madaket/Long Pond (landfill
and possible dredging), Sesachacha Pond (openings), Hummock Pond (refined opening
protocol). In addition, all of the Town’s estuaries should benefit from the recent fertilizer
application by-law. As a result, it is anticipated that the efficacy of these management
activities should be seen in the on-going monitoring results.
Summer 2018 appears to have sustained high water quality for the Nantucket Harbor
and Madaket Harbor systems. In contrast, Hummock Pond water quality appears to
have continued the decline started in 2016 which showed a decrease in overall water
quality compared to 2015. The variations in TN levels results primarily from opening
success. For instance, in spring 2017 the opening was only 1.5 days with high
precipitation, although the spring opening in 2016 was comparable to the duration of the
opening in 2015 (18 days and 15 days respectively). In contrast, Long Pond has
continued to show declines in TN concentrations over historic levels with parallel
improvements in water and habitat quality, although the inter-annual reductions appear
to be stabilizing.
Miacomet Pond, which is now functionally a eutrophic freshwater pond, saw a slight
improvement in 2017 as seen in lower TN concentrations and lower total pigments
(CHLA + Pheophytin) but worsened again in 2018. Miacomet Pond in 2017 and 2018 as
in 2016-2014 appears to have had phytoplankton production (e.g. chlorophyll-a)
stimulated by both N and P inputs as pond salinities declined to present freshwater
levels.
Water Quality in Sesachacha Pond appears to be directly related to the efficacy of its
seasonal openings. Water quality in 2010, 2012, 2013 was significantly improved over
the levels observed previously in the MEP analysis (November 2006). The lower TN
levels in Sesachacha Pond (2010-2013) versus historic levels documented by the MEP
indicated significant improvement of pond resources. Since there was no major shift in
nitrogen loading within the Sesachacha Pond watershed during that period of
improvement, it is almost certain that the amount of tidal flushing during a given artificial
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breaching is driving the variability in the observed summer TN level. The rise in TN
observed during the 2014 sampling suggests that a poor inlet opening may have
occurred in spring 2014, as watershed loading was unchanged. Short openings in
subsequent years (2015 {5 days}, 2016 {3 days}, 2017 {7 days}) suggests that inlet
opening efficacy has a significant effect on pond water quality as TN concentrations from
2014 to 2017 have steadily increased to nearly the same level as when the MEP
analysis was completed. However, the results indicate that the recent decline in water
quality observed in Sesachacha Pond since 2014 should be readily reversible if
sufficient flushing can be established.
The Trophic State of an estuary is a quantitative indicator of its nutrient related
ecological health and is based on key ecological metrics: concentrations of inorganic
and organic Nitrogen, water clarity (Secchi Depth), lowest measured concentrations of
Dissolved Oxygen (average of lowest 20% of summer measurements), and Chlorophyll-
a pigments (surrogate for phytoplankton biomass/blooms). Nutrient related trophic
health scales generally range from Oligotrophic (healthy-low nutrient) to Mesotrophic
(showing some signs of deterioration of health due to nutrient enrichment) to Eutrophic
(habitats significantly impaired and degraded, high levels of nutrients and organic matter
and community shifts).
Nantucket Harbor (with Madaket Harbor) is presently supporting the highest
water quality of Nantucket's estuaries. In 2018, all of the Nantucket and Polpis
Harbor monitoring stations were showing high water quality, slightly better than in
2017 Over the past 5 years, the main basin of Nantucket Harbor has supported
high quality waters, with only a periodic small level of decline in the uppermost
basin, Wauwinet basin. Summer 2017 saw a slightly lower TN level at station
NAN-2A (MEP sentinel station) and 2018 lower still. Summers 2016-2018
generally showed similar water quality in this basin as 2014 which also showed
improved chlorophyll-a and TN levels versus prior years. Nutrient management
activities associated with the Harbor (additional sewer hookups, jetty improvement
and oyster aquaculture) should result in even lower TN and chlorophyll levels and
reduce the likelihood of large phytoplankton blooms in the future.
Polpis Harbor basins which after showing moderate impairment in 2010 and 2012 have
been showing only low to no impairment in recent years, suggesting some improvement
over historic conditions. Polpis Harbor showed 2018 & 2017 TN levels similar to 2010,
2012 and 2015, slightly higher than 2013 and 2014. This variation makes continued
monitoring essential to clarify any trends in water quality and linkages to stream nitrogen
discharges. While the overall Nantucket Harbor System is generally supporting high
quality waters, the variability in the index in Wauwinet and Polpis basins should be
monitored to ascertain their long-term health and to determine the effectiveness of
restoration effort by the Town as it continues to move forward to meet the MassDEP
TMDL for this system. Overall, Nantucket Harbor appears to be relatively stable from
year to year with a gradual slight improvement with high index scores and higher level
metrics that support the contention that it is approaching its TMDL threshold, as is also
the case for Polpis Harbor. Planned sewering within the Nantucket watershed should
complete the restoration on nitrogen mitigated impairment within this estuarine system
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Madaket Harbor main basin in 2018 continued to support a high level of nutrient related
water quality. It has been the more enclosed basins of Hither Creek and Long Pond with
their reduced tidal flushing that have had nitrogen impairment problems. Over the 8
years of monitoring, Hither Creek (Station 1), which receives discharge from Long Pond
via Madaket Ditch, has consistently supported the poorest “health” status within the
Madaket Estuary. Hither Creek is clearly nitrogen enriched and showing continuing
impairment based on a variety of parameters, but has clearly improved since 2010.
Over the past 8 years the Trophic Index indicates that this basin has improved slightly
each year, going from fair-poor water quality and improving in a step-wise manner to
moderate water quality since 2014 with the exception of 2017 where TN levels rose, but
stayed within the range that has developed over the past 4-5 years. The main basin of
Madaket Harbor is showing relatively high water quality in each year but also shows a
possible improvement from 2010 to 2012 and has been generally stable at high water
quality in more recent samplings to 2018.
Long Pond is a large tributary basin to Madaket Harbor, which receives tidal flow
through the artificial connection of Madaket Ditch. Given the structure of the
basin and its watershed, Long Pond operates semi-independently from Madaket
Harbor. Long Pond’s Trophic Index scores for both monitoring stations (5 & 6) in
the 8 years of monitoring (2010, 2012-2018) clearly indicate poor nutrient related
water quality. However, based upon the 2018 results and the 8-year time-series,
it appears that the Town’s management of the landfill, has reduced the nitrogen
load from this source with the associated observed lowering of TN levels. While
the water quality Index for Long Pond is starting to improve in response to the
lower TN levels, the basin remains moderately impaired. While continued
monitoring will determine the final level of improvement, it does appear that the
reduction in N loading is occurring with beneficial effects. It should be noted that
the lack of major change in the Health Index for Long Pond results in part from the
relative coarseness of the Index, where sometimes large index score changes are
required to change the Index value. The analysis of key metrics (Chlorophyll-a,
water clarity-Secchi and total nitrogen) individually do show improving water
quality at stations 5 and 6 in 2012-2018 compared to 2010 and in the MEP
threshold analysis and a recent Town supported benthic animal analysis parallels
the water quality improvements.
Sesachacha Pond is a closed coastal salt pond that has its water quality
managed by periodically breaching the barrier beach to open the basin to tidal
exchange with the adjacent Atlantic Ocean waters. Sesachacha Pond was
evaluated under the Massachusetts Estuaries Project (MEP) which recommended
an additional mid-summertime opening (if logistically possible) as part of the pond
management strategy to enhance flushing of the pond and improve water quality
to reach the threshold without any need for infrastructure. The water quality
monitoring program in 2010, 2012 and 2013 showed that the pond nitrogen levels
were converging on the MEP Threshold (0.60 mg/L total nitrogen). Improved
openings resulted in total nitrogen (TN) levels dropping significantly from
historical levels in 2010 and 2012 with associated improvements in the levels of
water clarity and chlorophyll-a. However, with limited openings in 2014-2017, TN
has risen and has returned to near historic levels (~0.9 mg/L), with an
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improvement in 2018 (0.752 mg N/L), and with continuing impaired conditions. It
appears that these changes relate to the quality of the pre-summer opening.
Given the 2010-2013 period when robust openings occurred, it appears that a
solid opening program has the capability to improve the water quality metrics
pond-wide to levels near the TMDL nitrogen threshold.
Based upon the Index alone, changes in water quality in Sesachacha Pond over the
2010-2013 period were stabilized at moderate impairment of this estuary, with more
recent monitoring 2015-2017 seeing a trend toward poor water quality conditions with a
slight rebound in 2018 as TN levels rose (2015-2017) then declined (2018). It appears
that like other periodically opened ponds, the quality of the opening (amount of water
exchanged) controls the level of water quality in the following months. A closer
examination of the opening protocol and the linkage to resultant water quality is needed
for management of this system.
Hummock Pond is a closed coastal salt pond that is only periodically opened to
the ocean to flush out nutrients and organic matter on the ebb tide and receive
low nutrient saline waters on the flood tide. Creating sustained openings that are
sufficient to allow exchange of tidal waters for more than 4-5 days has been
difficult for this system due to its location on the coast and the large amount of
sand migration in the coastal zone which can rapidly reseal the inlet.
The present non-tidal state and level of watershed nutrient inputs have resulted in
moderate to poor nutrient related water quality throughout the pond, with poor
water quality conditions the present norm (2005-2007, 2010, 2012, 2013, 2014,
2015). Unfortunately, in 2016 the pond appears to have had lower water quality
in its upper and mid reaches than in previous years, although the lower basin did
not show this inter-annual variation. Similarly, in 2017 and 2018 water quality
declined even further throughout most of the estuary, including the lower basin.
This resulted from the poor spring 2017 and 2018 openings. There is generally a
small gradient in water quality with moderate to poor conditions near the ocean
and poor conditions in the uppermost basins, but this collapsed to generally poor
water quality throughout the system in 2017 and 2018. All of the metrics are
consistent with a nutrient impaired basin in all years. Based upon the monitoring
results it is clear that the nutrient related health of Hummock Pond is significantly
related to the success of its periodic openings and that the pond is presently
significantly impaired by nitrogen enrichment.
Miacomet Pond is a closed coastal salt/fresh pond that is rarely (over a decade ago)
opened to the ocean to flush out nutrients and organic matter on the ebb tide and
receive low nutrient saline waters on the flood tide. As a result of the lack of tidal flow
and continuous groundwater inputs, the pond is presently freshwater, with salinity levels
in each of the past 7 years of monitoring of <0.5 ppt, reaching a low of 0.1 ppt, 2015-
2017. The present non-tidal state and extent of watershed nutrient inputs has resulted in
a decline in nutrient related water quality throughout the pond for both nitrogen and
phosphorus, with poor water quality and habitat impairment the present norm. All of the
metrics for Miacomet Pond are consistent with a highly nutrient impaired basin.
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However, as the freshening of this basin has become complete and sustained, it likely
will have to be managed as a transitional freshwater system and will need to be
reassessed as such. Since Miacomet Pond may have storm over-wash in the future due
to climate change related storm intensification and sea level rise, it may be necessary for
management to create both a nitrogen and a phosphorus budget for this system and to
conduct short-term incubations to determine which nutrient is controlling pond health
under present and varying salinity conditions. It is likely that regions of the pond may be
sensitive to both nitrogen and phosphorus, such that overall both nutrients need to be
monitored and considered for management of Miacomet Pond, although phosphorus
management is clearly needed at this time.
Table ES-1. Summary of present status and trends of water/habitat quality of estuaries of
Nantucket based on present (2018) water quality monitoring data reconciled against historic data
collected from 2010-2017 and MEP nutrient threshold analyses undertaken for each system
except Miacomet Pond.
Estuary Type TMDL Status Trend Remedial Actions
Madaket Harbor Marine In Place Approaching N Target Improving Landfill Remediation
Long Pond Brackish In Place Approaching N Target Improving Landfill Remediation
Nantucket Harbor -
Polpis Harbor Marine In Place Approaching N Target Improving New Jetties, Planned
Sewers
Sesachacha Pond Brackish In Place Moderate Improvement Variable Targeted opening
Hummock Pond Brackish/Fresh In Place??Significantly Impaired Variable Targeted opening
Miacomet Pond Fresh None Significantly Impaired Unchanged Unknown
Summary of Present Status and Trend of Water Quality in Nantucket's Estuaries
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The Technical Memorandum on the 2018 Nantucket Water Quality Monitoring Program is
organized consistent with previous SMAST water quality monitoring summaries (2010 and 2012
- 2017) to allow direct comparison to data from the previous years of monitoring. The tech
memo does include summary tables for each year of the program so that this can be used as a
both the 2018 review and a program summary. As was the case with the 2017 summary, the
2018 summary does not include an overview of the program or the summary of the sampling
approach as neither of those two sections have changed from previous years, instead they are
included by reference. The 2018 summary is focused specifically on the following:
1. Results of Sampling: Summary of Water Quality Results
Nantucket Harbor
Madaket Harbor
Long Pond
Hummock Pond
Miacomet Pond
Sesachacha Pond
Polpis Harbor Streams
Oyster Aquaculture Potential Sites
2. Trophic State: Water Quality/Eutrophication Status
3. Recommendations for Future Monitoring
As in previous years, the 2018 water quality monitoring of Nantucket's fresh and
saltwater systems was focused on summer-time conditions, as the warmer months
typically have the lowest water quality conditions, hence are critical period for resource
management. As in previous years (2010, 2012-2017), the 2018 approach utilized for
the collection and analysis of water samples from each of the estuaries of Nantucket
remains the same. This consistency is intended to maximize the value of the results by
making the data perfectly cross-comparable to water quality monitoring data collected
across the Island of Nantucket from previous years and to previous Massachusetts
Estuaries Project results for Nantucket estuaries as well as more broadly to estuaries
throughout the region (Cape Cod, Martha's Vineyard). In this manner, inter-ecosystem
comparisons can be made to better assess system health/impairment and function and
to formulate appropriate nutrient management strategies. This allows individual towns
such as Nantucket to directly benefit from lessons learned throughout the wider region. It
should be noted that in 2018 (as was the case in 2017), compliance monitoring samples
were collected from sentinel locations in Nantucket Harbor, Sesachacha Pond and
Madaket Harbor as established under the Massachusetts Estuaries Project. Those
samples are required of the Town by MassDEP and are denoted by a (C) in the sample
ID.
As in past years, UMD-SMAST Coastal Systems Program (CSP) scientists focused
primarily on the analysis of samples collected from the field effort, data analysis and
overall program coordination. The Nantucket Natural Resources Department staff
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primarily focused on coordination of field efforts, field sampling and data collection on
physical parameters and water quality improvement efforts.
The goals of the monitoring program remain unchanged from previous years, primarily
to:
4. determine the present (2018) ecological health of each of the main salt ponds and
estuaries within the Town of Nantucket,
5. gauge (as historical data allows) the decline or recovery of various salt ponds and
embayments over the long-term (also part of TMDL compliance), and
6. provide the foundation (and context) for development of potential alternatives for
nutrient and resource management and quantitative measures of success.
This latter point (3) is critical for restoration planning should a system be found to be
impaired or trending toward impairment, which requires targeted management actions
for restoration.
As was the case in 2010, 2012 - 2017 sampling efforts, the 2018 sampling program
focused on the summer/early fall months (June - September). In addition to the standard
estuarine sampling, in the 2016 sampling season 2 additional sampling events were
completed in Sesachacha Pond to monitor the efficacy of the spring opening (breaching
barrier beach) and in Hummock Pond an additional event was completed in April to
represent pre-opening conditions and the regularly scheduled May sampling event was
utilized to determine water quality in the pond after the pond closed. Monitoring of the
openings of Sesachacha Pond and Hummock Pond were NOT continued in 2017 and
2018.
Water samples were collected from 6 estuarine systems (Figures 1, 2, 3, 4 and 5) on
multiple dates (“events”) following the schedule presented in Table 1a (2018), Table 1b
(2017), Table 1c (2016), Table 1d (2015), Table 1e (2014), Table 1f (2013). Table 1g
(2011) and Table 1h (2010). Samples collected in 2018 were obtained from the same
sampling station locations and the same depths as in previous years to maximize cross
comparability and to gauge temporal changes. It should be noted that the Town of
Nantucket did undertake water quality monitoring in 2011, however, those samples were
analyzed by a lab other than the Coastal Systems Analytical Facility at the UMASS
School for Marine Science and Technology. The 2011 water quality data were
presented in tabular form in Appendix A in Annual Technical Memoranda of 2012 and
2013 and are not being reproduced again herein.
As in all previous years, the physical/environmental parameters measured in the
estuaries during the 2018 sampling season included: total depth, Secchi depth (light
penetration), temperature, conductivity/salinity (YSI meter), general weather (rain,
cloudiness, etc), wind force and direction, dissolved oxygen levels and observations of
moorings, birds, shell fishing and unusual events (fish kills, algal blooms, etc).
Laboratory analyses of estuarine waters included: salinity, nitrate + nitrite, ammonium,
dissolved organic nitrogen, particulate organic carbon and nitrogen, chlorophyll-a and
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pheophytin-a and orthophosphate. As initiated in the summer of 2015, the estuarine
water quality monitoring undertaken in 2016, 2017 and 2018 included an additional 3
stream locations. During the summer 2016 season, stream station STA-3 was dropped
due to no flow and a station STA-4a was added to clarify water quality conditions in the
stream outflow associated with cranberry bogs up-gradient of STA-4. In 2017 a fourth
stream station was added (WPH outlet) to directly measure flow and nutrient load into
Western basin of Polpis Harbor. In total, 2018 stream sampling took place at 4 stations:
STA-4, STA-4A, STA-6 and WPH outlet.
In 2018, 24 field duplicates (11% of the total number of samples collected {n=225}) were
taken as part of the field sampling protocol for QA analysis. Data were compiled and
reviewed by the laboratory for accuracy and evaluated to discern any possible artifacts
caused by improper sampling technique, physical disturbance, etc. In addition, some
samples were rerun to confirm prior results.
The Town of Nantucket has been working for decades to protect and more recently
restore its estuaries and their aquatic resources. At present, activities to lower nitrogen
enrichment and its negative impacts to water and habitat quality are ongoing in 4
estuarine systems: Nantucket Harbor (jetties and sewers), Madaket/Long Pond (landfill
and possible dredging), Sesachacha Pond (openings), Hummock Pond (refined opening
protocol). In addition, all of the Town’s estuaries should benefit from the recent fertilizer
application by-law. As a result, it is anticipated that the efficacy of these management
activities should be seen in the on-going monitoring results.
As detailed below, summer 2018 appears to have sustained high water quality for the
Nantucket Harbor system (2018 embayment wide TN average of 0.31 mg/L, 2017 =
0.35 mg/L, 2016 = 0.35 mg/L, 2015 = 0.37 mg/L). In contrast, Hummock Pond water
quality appears to have continued the decline started in 2016 which showed a decrease
in overall water quality compared to 2015 (2018, 2017 and 2016 embayment wide
average TN levels remain high at 0.83, 1.01 and 0.80 mg/L (respectively vs 2015 = 0.58
mg/L). The variations in TN levels results primarily from opening success for instance in
spring 2017 the opening was only 1.5 days with high precipitation, although the spring
opening in 2016 was comparable to the duration of the opening in 2015 (18 days and 15
days respectively). Long Pond TN concentrations have improved over historic levels
although the reduction appears to be stabilizing (0.587 mg/L in 2018). Miacomet Pond,
which is now functionally a eutrophic freshwater pond, saw a slight improvement in 2017
as seen in lower TN concentrations and lower total pigments (CHLA + Pheophytin).
Water Quality in Sesachacha Pond appears to be directly related to the efficacy of its
seasonal openings. Water quality in 2010, 2012, 2013 (mean TN = 0.671 mg/L, Chla =
5.5 ug/L) was significantly improved over the levels observed previously in the MEP
analysis. The lower TN levels in Sesachacha Pond (2010-2013) versus historic levels
documented by the MEP indicated improvement of pond resources most likely due to
modified breaching of the pond as recommended by the MEP analysis. Since there was
no major shift in nitrogen loading within the Sesachacha Pond watershed during that
period of improvement, it is almost certain that the amount of tidal flushing during a given
artificial breaching is driving the variability in the observed summer TN level. The rise in
TN observed during the 2014 sampling suggests that a poor inlet opening may have
occurred in spring 2014, as it is unlikely a significant change in the watershed load
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occurred to drive the increase in TN from one summer to the next. Short openings in
subsequent years (2015 {5 days}, 2016 {3 days}, 2017 {7 days}) suggests that inlet
opening efficacy has a significant effect on pond water quality as TN concentrations from
2014 to 2017 have steadily increased to nearly the same level as when the MEP
analysis was completed. In recent years (2014-2017) water quality has declined (mean
TN = 0.933 mg/L, Chla = 8.4 ug/L) and is again approaching MEP levels of enrichment.
The amount of flushing with the openings is reflected in the significantly higher salinities
in 2010-2013 versus 2014-2017, 17.9 PSU and 11.6 PSU, respectively. Higher salinities
reflect more flushing which is correlated with lower TN and total chlorophyll a levels. The
2016 water quality analysis confirmed that the significant improvement in Sesachacha
Pond seen previously had diminished and the Pond has declined in nitrogen related
water quality over the past 4 years (2014-2017) almost certainly due to the quality of the
inlet openings. The important role of the pond openings is further supported by the fact
that average TN concentration in Sesachacha Pond was higher (1.00 mg/L TN) in 2016
which received a 3 day opening compared to average TN concentrations observed in
2017 (0.88 mg/L TN) given a 7 day opening. These results indicate that the recent
decline in water quality observed in Sesachacha Pond since 2014 should be readily
reversible if sufficient flushing can be maintained. The effect of improved pond flushing
is discussed in detail in the MEP Sesachacha Pond Nutrient Threshold Report submitted
to the Town of Nantucket in 2006.
Table 1a. Sampling Schedule for 2018 Nantucket Water Quality Monitoring Program
Month Nantucket
Harbor
Madaket
Harbor
Long
Pond
Sesachacha
Pond
Miacomet
Pond
Hummock
Pond
Polpis
Streams
Oyster
Sites
Jan
Feb
Mar
April April 25
May
June June 5 June 7 June 13 June 11 June 11 June 13 June 6,26 June 5
July July 5 July 2 July 17 July 10 July 10 July 17 July 24 July 5
August August 1 August 2 August 8 August 14 August 14 August 8 August 21 August 1
September Sept. 12 Sept. 13 Sept. 5 Sept. 4 Sept. 4 Sept. 5 Sept.12
October
November
December
Total
Events
4 4 4 4 4 4 5 4
12
Table 1b. Sampling Schedule for 2017 Nantucket Water Quality Monitoring Program
Table 1c. Sampling Schedule for 2016 Nantucket Water Quality Monitoring Program
Month Nantucket
Harbor
Madaket
Harbor
Long
Pond
Sesachacha
Pond
Miacomet
Pond
Hummock
Pond
Polpis
Streams
Oyster
Sites
Jan
Feb February
8
Mar March 30 March 29 March 27
April April 27
May May 18 May 16 May 10 May 4 May 4 May 3 May 23 May 17
June June 14,29 June 27 June 13 June 22 June 19 June 12 June 14
July July 12,27 July 11 July 10 July 6,31 July 6 July 10 July 5 July 12
August August 10,24 August 9 August 7 August 3 August 7 August 15 August 10
September Sept. 25 Sept. 12 Sept. 27 Sept. 5 Sept. 5 Sept. 13 Sept. 11 Sept.25
October Oct. 24
November
December
Total
Events
8 5 5 6 5 5 9 5
Month Nantucket
Harbor
Madaket
Harbor
Long
Pond
Sesachacha
Pond
Miacomet
Pond
Hummock
Pond
Polpis
Streams
Oyster
Sites
Jan
Feb
Mar March 16
April April 6,25 April 11 April 20
May May 9 May 11 May 12 May 18 May 18 May 10 May 17 May 12
June June 8, 23 June 7 June 6 June 15 June 15 June 13 June 14 June 27
July July 8, 25 July 6,28 July 13 July 5,18 July 5 July 13 July 21 July 11
August Aug 8,23 Aug 10,24 Aug 4 Aug 3 Aug 3 Aug 4 Aug 25
September Sept 21 Sept 22 Sept 19 Sept 12 Sept 13 Sept 19 Sept 20
October
November
December
Total
Events
8 7 5 8 5 6 5 5
13
Table 1d. Sampling Schedule for 2015 Nantucket Water Quality Monitoring Program
Table 1e. Sampling Schedule for 2014 Nantucket Water Quality Monitoring Program
Note: * The September 15 sampling of Nantucket Harbor only involved one station (NAN-4).
Month Nantucket
Harbor
Madaket
Harbor
Long
Pond
Sesachacha
Pond
Miacomet
Pond
Hummock
Pond
Polpis
Streams
Oyster
Sites
Jan
Feb
Mar
April
May May 7 May 12 May 11 May 11 May 12, 27
June June 9, 22 June 8 June 17 June 15 June 15 June 17 June 8 June 9
July July 8, 20 July 6 July 13 July 15 July 15 July 13 July 6 July 6
August Aug 4,19 Aug 5 Aug 17 Aug 10 Aug 10 Aug 12 Aug 3, 31 Aug 3
September Sept 1 Sept 3 Sept 14 Sept 10 Sept 10 Sept 9 Sept 2
October
November
December
Total
Events
8 4 5 5 5 6 4 4
Month Nantucket
Harbor
Madaket
Harbor
Long Pond Sesachacha
Pond
Miacomet
Pond
Hummock
Pond
Jan
Feb
Mar
April
May May 6 May 14 May 20 May 14 May 7, 19
June June 4, 17 June 19 June 11 June 12 June11 June 10
July July 1, 17 July 2 July 23 July 30 July 30 July 23
August Aug 4, 14 Aug 18 Aug 21 Aug 19 Aug 19 Aug 21
September Sept 2, 15* Sept 15 Sept 4 Sept 4 Sept 18 Sept 18
October
November
December
Total Events 8 4 5 5 5 6
14
Table 1f. Sampling Schedule for 2013 Nantucket Water Quality Monitoring Program
Table 1g. Sampling Schedule for 2012 Nantucket Water Quality Monitoring Program
Month Nantucket
Harbor
Madaket
Harbor
Long Pond Sesachacha
Pond
Miacomet
Pond
Hummock
Pond
Jan
Feb
Mar
April
May May 28 May 22 May 22 May 21
June June 13, 25 June 12 June 4,26 June 5 June 5 June 6
July July 17, 30 July 16 July 10 July 9 July 9 July 2
August Aug 13, 28 Aug 12 Aug 21 Aug 21 Aug 6 Aug 14
September Sept 9 Sept 10 Sept 24 Sept 19 Sept 24 Sept 18
October
November
December
Total Events 7 5 5 5 5 5
Month Nantucket
Harbor
Madaket
Harbor
Long Pond Sesachacha
Pond
Miacomet
Pond
Hummock
Pond
Jan
Feb
Mar
April
May May 29
June June 7, 28 June 12 June 25 June 20 June 20 June 27
July July 9, 26 July 11 July 24 July 19 July 19 July 31
August Aug 7, 22 Aug 8 Aug 21 Aug 23 Aug 23 Aug 24
September Sept 6 Sept 7 Sept 25 Sept 25 Sept 27 Sept 26
October
November
December
Total Events 8 4 4 4 4 4
15
Table 1h. Sampling Schedule for 2010 Nantucket Water Quality Monitoring Program
Month Nantucket
Harbor
Madaket
Harbor
Long Pond Sesachacha
Pond
Miacomet
Pond
Hummock
Pond
Streams
Jan
Feb
Mar
April
May May 18 May 20 May 19 May 26 May 26 May 25
June June 2, 17 June 3, 15 June 17 June 24 June 24 June 29 June 28
July July 1, 15,
30
July 16, 27 July 29 July 26 July 26 July 28
August Aug. 13 Aug. 12, 30 Aug. 11 Aug. 26 Aug. 26 Aug. 27
September Sept. 1, 14 Sept. 13 Sept. 15 Sept. 23 Sept. 23 Sept. 28
October Oct. 21
November
December
Totals 10 8 5 5 5 5 1
16
Figure 1. Madaket Harbor and Long Pond sampling stations 2010, 2012, 2013, 2014, 2015, 2016, 2017 and 2018.
17
Figure 2. Nantucket Harbor sampling stations 2018. Station NAN-8 (the cut) was only sampled in 2010 and location changed in 2011 -
2018. Nantucket Harbor and Polpis Harbor each have nitrogen thresholds in the MassDEP/USEPA TMDL for this system.
18
Figure 3. Sesachacha Pond sampling stations 2010, 2012, 2013, 2014, 2015, 2016, 2017 and 2018. This system has a nitrogen
threshold set in its site-specific MassDEP/USEPA TMDL..
19
Figure 4. Hummock Pond sampling stations 2010, 2012, 2013, 2014, 2015, 2016, 2017, 2018. Station 7 is in Head of Hummock, a kettle
pond connected by an artificial channel to the estuary with limited exchange from Station 7 to Station 8.
20
Figure 5. Miacomet Pond sampling stations 2010, 2012, 2013, 2014, 2015, 2016, 2017 and
2018. Miacomet Pond is currently functioning as a fresh pond.
Station 3
Station 1
Station 2
Station 3
Station 1
Station 2
21
Figure 6. Polpis Harbor Stream Sampling locations (ST-4, 4A, 6B and WPH-outlet). Stream
sites sampled in 2016 and 2017 (shown as yellow pins). WPH-outlet sampled only in 2017 and
2018. Water samples from mid depth in water exiting culverts.
Figure 6a. Polpis Harbor Stream Sampling locations (ST-4, 4A, 6B and WPH-outlet) relative to
estimated direction of flow as determined by the Town of Nantucket.
22
Figure 6b. Polpis Harbor Stream Sampling locations (ST-4, 4A, 6B) 2016 (shown as yellow
pins). Water samples from mid depth in water exiting culverts.
Figure 6c. Polpis Harbor Stream Sampling locations (ST-3,4,6B) 2015 (yellow pins). Water
samples from mid depth in water exiting culverts. ST-3 was dropped in 2016 due to zero flow.
23
Figure 7a. Sampling locations associated with potential oyster aquaculture deployments in Nantucket
Harbor (ORS-2,3,4,5,6) and Madaket Harbor (ORS-1) sampled in 2015. ORS-2,4,6 sampled in 2016,
2017 and 2018. Sites are associated with possible oyster aquaculture areas (yellow pins). ORS4 was
the selected reef location and reef construction began in June 2017. Spat on shell was deployed in the
Fall 2017.
Figure 7b. Oyster Aquaculture Sampling location Madaket Harbor (ORS-1) 2015 (yellow pin). Site is
associated with possible oyster aquaculture areas but was not sampled in 2016, 2017 or 2018.
24
Summary of 2018 Water Quality Results for Nantucket Sampling
Estuarine Water Quality: While there were some localized areas supporting inter-
annual variation in water quality (Hummock Pond {-}, Miacomet Pond {-}, Nantucket
Harbor {+}1, see below), the overall trends in water quality observed in 2018 follow and
expand the pattern observed in previous years. As in previous years, water samples
collected from June through September in the estuarine systems indicate that organic
nitrogen (dissolved + particulate) dominates the Total Nitrogen pool (99%-89% in 2018,
86%-99% in 2017 depending on the estuary vs. 92-98% in 2016 and 96% in 2015
alone), while bio-available nutrients in the form of nitrite+nitrate (NOx) and ammonium
(NH4) (combined DIN) in estuarine waters account for 1% - 10% in both 2018 and 2017
compared to 2% - 10% of the TN pool in 2016 and 4% of Total Nitrogen pool in 2015
(Tables 3a-h and Figures 15,16). Only the uppermost reach of Hummock Pond (salinity
2 ppt) had a slightly higher proportion inorganic nitrogen, likely due to its nearly
freshwater status. The observed distribution of the nitrogen fractions comprising total
nitrogen are typical for estuarine systems throughout New England, where nitrogen is
the nutrient responsible for eutrophication and therefore the critical nutrient for
management.
It is the uptake of bio-available nitrogen, entering via groundwater to estuarine waters,
primarily by phytoplankton that is transforming inorganic to organic nitrogen forms and
under nitrogen enrichment is the mechanism through which water quality becomes
impaired. Where tidal flushing is effective, much of this produced particulate matter
along with dissolved nutrients is washed out of the system resulting in good water clarity
as evidenced by the greater Secchi depth readings in the main basins of Nantucket
Harbor and Madaket Harbor in 2017 (Table 3a), as noted in prior years as well (Tables
3b-h). Consistent with the water clarity and TN levels, corresponding chlorophyll-a
pigment concentrations are lowest (1-5 ug/L) at the outer stations (nearest the tidal
inlet) of these well flushed systems (Table 3a-h, Figures 8,9). The observed level of
variation is common and underscores the need for long-term monitoring to detect water
quality trends.
Nantucket Harbor and Madaket Harbor are both well flushed basins but tended to have
slightly higher water quality with relatively low phytoplankton biomass (chlorophyll-a) in
2017 and 2018compared to 2016 (all stations in Madaket Harbor and most stations in
Nantucket Harbor). In Nantucket Harbor, station Nan-5 showed a lower level of total
pigment in 2017 compared to 2016, but returned to 2016 levels in 2018, however, the
difference was slight and the levels in all years were relatively low (7.2 to 4.8 ug/L). In
Madaket Harbor the total pigment levels in 2017 were consistently higher compared to
most other years except 2010 which showed higher chlorophyll levels than all years
monitored to date. This is consistent with the water clarity observed in 2017 (Nantucket
Harbor station 3 secchi depth 2015 = 1.45 m, 2016 = 2.34 m, 2017 = 2.30m, 2018 =
2.00 m, Madaket Harbor MH-2 secchi 2.2 meters in 2015, 1.7 meters in 2016, 1.68
meters in 2017 and 2.81 m in 2018) as turbidity is primarily the result of organic
particulates, e.g. phytoplankton. The parallel measurements of total nitrogen (TN) are
generally consistent with the chlorophyll-a results, showing a positive relationship
between changes in TN levels with changes in chlorophyll-a levels (see below). This is
particularly apparent in Nantucket Harbor (station 5 and 6, Polpis as well as station 2
1 {+} indicates improved conditions in 2017; {-} indicates declining conditions in 2017.
25
mid harbor and the sentinel station 2A) and provides additional evidence that nitrogen is
controlling the level of eutrophication in these systems.
Figure 8. Average Chlorophyll-a (CHLA) concentrations by station in the well flushed Nantucket
Harbor system during the summer 2018 sampling season. Stations Nan-5 and 6 are in Polpis
Harbor the rest relate to the main basin. Note that 2018 levels were slightly above average
within the upper basins (Nan-5 slightly higher in 2018 compared to 2017 and 2016, Nan-6
slightly higher in 2018 compared to 2017 and 2016) and relatively constant throughout the
Harbor at a level consistent with low-moderate nitrogen enrichment. The large blooms of 2012
and 2010 have not reoccurred in recent years.
Figure 9. Average Chlorophyll-a (CHLA) concentrations by station in the well flushed Madaket
Harbor system during the summer 2010-2017 sampling seasons. Stations MH-2,3,4 are in the
main open basin and consistently show moderate to low chlorophyll a pigments, MH-1 is the
0
2
4
6
8
10
12
14
16
Nan-3 Nan-6 Nan-5 Nan-2 Nan-7 Nan-1 Nan-8 Nan-4Chlorophyll-a + Pheo (ug/L)Nantucket Harbor Total Pigment Level
2010 2012 2013 2014 2015 2016 2017 2018
26
MEP sentinel station in Hither Creek and recorded the highest levels to date. The 2010 blooms
had not been as prevalent in follow-on years however in 2017 and 2018 total pigment levels
were notably higher at stations MH-1 and MH-2.
Where tidal flushing is more restricted in Long, Hummock, Miacomet and Sesachacha
Ponds, the moderate levels of water clarity were consistent with the moderate to high
chlorophyll-a concentrations that have a higher (2x-3x) average compared to the open
basins of Nantucket and Madaket Harbors. Sesachacha and Long Pond generally had
similar total chlorophyll-a levels 2015-2018, significantly lower than Miacomet and
Hummock Ponds, possibly related to the total annual water exchange in each system.
Average chlorophyll-a concentrations in 2018 and 2017 in the poorly flushed basins of
Long Pond were 11.0 and 16.5 ug/L (max. 23.5 ug/L) and in Sesachacha Pond, 13.9
and 9.0 ug/L (max. 27.7 ug/L). Nantucket’s poorest flushed basins: Hummock and
Miacomet Ponds had the highest plankton levels in 2018 and 2017 with Hummock Pond
averaging 19.4 ug/L and 22.5 ug/L, respectively (max. 77.3 ug/L) and Miacomet Pond
averaging 25.0 ug/L and 9.7 ug/L, respectively (max. 112.8), (Table A, Figures 10,
11,12,13). These general patterns were also observed in Sesachacha, Long,
Hummock, Miacomet Ponds monitoring results for 2015 and 2016 (6.7 and 11.1 ug/L,
6.1 and 9.3 ug/L, 15.52 and 48.7 ug/L) with highest total chlorophyll levels generally
being observed in the freshwater Miacomet Pond basin, and upper Hummock Pond and
Sesachacha and Long Ponds which generally show lower blooms but show higher
levels during periods when they freshen due to poor openings. In Hummock Pond
chlorophyll-a levels were noticeably higher in 2018 and 2017 compared to 2016 and
2015, likely due to less effective openings in recent years (a persistent bloom of
Dolichospermum was also observed for a significant portion of the 2017 sampling
period). The low flushing of Hummock Pond in 2018 and 2017 can be seen in the low
salinity (4.9 and 3.5 PSU) compared to 2016 and 2015 (6.5 and 5.8 PSU, respectively).
The multi-year results clearly show that 2010 was the poorest water quality year, 2010-2018, in
each of Nantucket’s estuaries. Over the past 4 years, chlorophyll-a levels in Long Pond,
Hummock Pond, Miacomet Pond and Sesachacha Pond have declined compared to historic
levels (MEP) and 2010 but do show inter-annual variation (e.g. all ponds higher in 2017
compared to 2016) due to differences in opening duration, rainfall, temperature, etc. However,
Sesachacha Pond and Long Pond have showed much improved water quality compared to
their long term status during the MEP assessment. Sesachacha Pond historic chlorophyll-a
levels were generally >20 ug/L, frequently >60 ug/L, with blooms as high as 100 ug/L, while
Long Pond has seen improvements apparently due to decreasing nitrogen inputs. It is
becoming clear that that Hummock Pond and Sesachacha Pond water quality is tightly linked
to the success of their periodic openings. Sesachacha Pond showed significantly improved
conditions in 2012 and 2013 with successful openings, but has showed recent decline, 2014-
2018. However, conditions remain improved over historic levels. The 2012-2013 conditions
approached the TMDL target TN levels to restore nitrogen impaired habitats, with the recent
trend in pigment levels (2014-2018) in concert with renewed decline in TN levels in 2016,
2017 and 2018. The increase in total pigment levels appears to be related to duration of
spring openings in respective sampling years: 2018 { 3 day spring opening}, 2017 {7 day
spring opening}, 2016 {3 day spring opening}, 2015 {5 day spring opening}). Given that
opening duration may not accurately reflect flushing success in all cases, salinity was analyzed
as the response to tidal flushing. In this case it appears that the low nitrogen/chlorophyll years
(2012 & 2013) also had the highest salinities on record (24.7 and 17.0 PSU), whereas in 2018
27
salinity was 13.2 PSU and the recent water quality decline is under salinity conditions of 11.3-
11.6 PSU. Note that the MEP indicates that a salinity of 22 PSU should be associated with
high water quality in Sesachacha Pond, consistent with the monitoring program results.
It is important to note that creating sustained openings in Sesachacha Pond is difficult due to
the dynamic coastal processes which move to refill and close the tidal channel almost
immediately. However, when openings have been successful there was a dramatic
improvement in pond water quality. It appears from all of the accumulated information that it is
unlikely that the Town will be able to reproducibly have good openings despite planning
openings based on weather and tides, therefore a combination of openings and nitrogen
management will likely be needed for a stable restoration.
As previously noted in past summary reports, the temporal data indicate that both
Sesachacha Pond and Hummock Pond can be significantly restored by effective pond
openings and that salinity is a good metric from which to gauge opening “success”
(higher resultant salinity = lower TN). As more data is available, it will be possible to
derive predictions of the water quality response from opening metrics which can then
be used by the Town in refining what is a difficult process of pond openings. In the case
of Sesachacha Pond, where openings are through a barrier beach subject to very active
coastal processes, if openings cannot be made more effective, it may be necessary to
consider nutrient load reducing strategies in the watershed or in situ processes to
improving water quality, such as use of oysters to lower TN levels. This in situ
approach of using the filtering capacity of oysters to improve water quality is being
considered by a number of towns on Cape Cod (Falmouth, Orleans, Mashpee) as well
as across Buzzards Bay (Westport).
After the high chlorophyll-a levels in 2010, 2012, Long Pond has maintained its phytoplankton
levels at a moderate to high level. However, in 2017 the total chlorophyll levels increased
noticeably which were not repeated in 2018 where levels declined significantly to those of
2015, while 2016 remains as the lowest levels of record, a pattern mirrored in the TN results.
The initial decline (post-2012) was noted in the previous 3 monitoring years and is possibly a
result of activities at the landfill leading to declining nitrogen inputs to pond waters.
Interestingly, while station LONG 5 in 2017 showed a dramatic increase, station LONG 6
closest to the outflow point from Long Pond to Madaket Ditch,(while higher than most previous
years) still showed similar chlorophyll levels as in past years, consistent with the observed
algae bloom (Diatoms) in the lower portion of Long Pond furthest away from the outflow that
was captured during the June and July sampling dates (personal communication, Kaitlyn
Shaw). 2018 was a return to the long-term total chlorophyll-a pattern, and had the lowest TN
levels on record. As previously recommended in 2016 and 2015, a detailed assessment of the
current landfill effect on groundwater quality flowing to Long Pond is now underway for making
predictions as to the likely extent of improvement possible. It should be noted, however, that a
benthic infaunal survey was undertaken in November 2017 by scientists from the Coastal
Systems Program, UMD-SMAST, at the request of the Town of Nantucket. Sediment samples
were collected using the same protocols as employed by the Massachusetts Estuaries Project
thereby allowing direct cross comparison of 2017 and 2003 results when infauna was last
surveyed by the MEP as part of the Long Pond habitat assessment. The 2017 infaunal survey
results indicated a significant improvement in habitat quality mirroring the decline in water
column TN levels and indicating that Long Pond was approaching its nitrogen TMDL threshold
set by MassDEP and USEPA under the Clean Water Act.2
2 Technical Memorandum: Updated Benthic Infauna Survey of Long Pond, Nantucket. 2018. B.L. Howes, S.J.
28
Comparison of the 2003 and 2017 Long Pond benthic animal habitat surveys with the
preceding 3-5 years of water quality (TN & chlorophyll-a) data indicated some clear shifts in
the habitat quality of the Long Pond Basin. In contrast, the semi-isolated Head of Long Pond
showed less certain shifts in benthic habitat quality. Specifically, nitrogen related water quality
has significantly improved within the main basin of Long Pond in the 2002-2004 and 2013-
2017 monitoring records. TN levels associated with the 2003 and 2017 benthic surveys
declined from 0.883 mg TN L-1 to 0.719 mg TN L-1 at Town Station 6 (LOPO-4) and from 0.971
mg TN L-1 to 0.725 mg TN L-1 at Town Station 5 (LOPO-5). Given the structure and brackish
water environment of the main basin of Long Pond the benthic habitat has clearly improved
from 2003 to 2017, paralleling the water quality improvement. The assessment of improved
benthic animal habitat is based on the loss of most stress indicator species, increase in major
species (from 10 to 12), increase in average number of species from 5 to 9, the increase in
diversity from 1.19 to 1.78 and the recolonization of the benthic habitat at station 8 from no
species/organisms in 2013 to 13 species in 2017. For a wetland dominated brackish system
the benthic animal habitat seems to be transitioning to high quality, although diversity remains
a bit low.
In addition to infauna surveys, nutrient testing of landfill effluent was initiated in 2017 by
the Public Works department and CDM-Smith who already monitor the wells. These efforts
are being used to update the nutrient load values to Long Pond based on new nitrogen
concentrations and groundwater information and should be integrated into the detailed
assessment of the effect of the landfill activities on Long Pond water and habitat quality.
Presently, Long Pond is generally showing signs of improving. It does, however, continue to be
nitrogen enriched and moderately impaired based upon the suite of water quality metrics.
In contrast to the improvements seen in Long Pond, Miacomet Pond which is not open
to tidal flows, remains very fresh (avg. salinity 0.1-0.2 PSU), continues to show high
chlorophyll-a levels in 2018 (27.8 ug/L seasonal average), although 2017 and 2016
levels were generally lower). Miacomet Pond is still clearly supporting poor water
quality conditions with high TN, TP and total chlorophyll-a levels (system average 0.741
mg TN/L and 0.070 mg TP/L, respectively in 2018) and high total chlorophyll-a levels
(25 ug/L), poor water clarity and moderate oxygen depletion, all indicators of a nutrient
impaired basin. Additionally, given how fresh Miacomet Pond has become,
phosphorous as a driver of nutrient impairment must be considered.
The upper portion (Hum-8 and Hum-5) of Hummock Pond showed overall total pigment
and chlorophyll-a levels in summer 2018 and 2017 higher than 2016 and 2015 and most
other years in general. This is a significant shift as 2016 levels were lower than 2010,
2012, 2013 and showed moderate levels in the mid reaches but with stations in the
lower portion (Hum-1 and Hum-3) closer to the barrier beach having slightly lower total
pigment levels compared to most years. However, in 2018 and 2017 total chlorophyll-a
levels basin wide were almost three time those of the previous 2 years (22.1 and 24.2
ug/L vs. 7.5 and 9.2 ug/L), In 2018 and 2017, the lower stations (Hum-1 and 3) were
noticeably higher than 2010 levels which were previously considered the highest of all
years monitored by the island-wide water quality monitoring program. The 2014 results
Sampieri, R.I. Samimy. Coastal Systems Program, SMAST-UMASS Dartmouth, 12pp..
29
remain the lowest levels measured over the 2010-2017 monitoring period and while
2016 was slightly higher than 2015 in the upper reaches of the system, chlorophyll
levels in 2016 were still moderate-high as a metric of eutrophication. In 2018 and 2017,
chlorophyll levels were indicative of eutrophication. While three years (2014, 2015 and
2016) represent the beginning of a restoration trend, the lower levels in these three
years are consistent with an improved opening protocol implemented in 2014 that was
not able to be repeated in 2018 and 2017. The new opening protocol stemmed from the
Town and the Nantucket Land Council supporting a project specifically to refine the
opening protocol for Hummock Pond to maximize the amount of tidal flushing achieved
by each opening. The April 2014 opening of Hummock Pond was moderately
successful and was followed by a more effective opening that Fall (October 2014) which
lowered TN levels in the pond and raised its salinity. In 2015, the revised opening
protocol allowed for a 15 day spring opening and a 17 day fall opening further flushing
the pond. This was followed by a 18 day spring opening in 2016 in advance of the
summer sampling season. It is almost certain that the sequence of good openings in
past years was the cause of the relatively low total pigment and TN conditions in the
lower half of Hummock Pond in 2016. By comparison, in 2017 a spring opening was
initially achieved but it lasted less than 1 day and was followed by another opening
which only lasted 1.5 days in duration. The lack of an effective spring opening of
Hummock Pond is likely the main contributor to the decreased nutrient related water
quality observed in 2017 and 2018, consistent with the lower overall pond (Stations 1-7)
salinity (2018 = 5.0 PSU; 2017= 3.5 PSU; 2016=6.5 PSU indicative of less flushing in
2017.
As flushing in the uppermost portions of Hummock Pond tend to be limited, total
pigment (and component chlorophyll-a) showed to be significantly higher (3x) at Hum-8
in 2017 and 2018 (45.0 and 50.7 ug/L, respectively) compared to 2016. Head of
Hummock (sta. 8) consistently has a lower salinity and higher total chlorophyll and TN
levels than the adjacent stations consistent with the Head of Hummock not being tidally
well connected to the main basin of Hummock Pond through its narrow shallow channel.
Total pigment and chlorophyll-a generally remains the lowest at each monitoring station
in 2014 with 2015 and 2016 being the next lowest when compared to prior years. In
April 2016 and 2015, Hummock Pond was opened and water levels and water quality
were monitored before and after the opening. Both the April 2016 and 2015 openings
appeared to be more effective than the fall 2014 opening as seen in the enhanced water
quality during the 2016 and 2015 summers. Not surprisingly, in 2016 at station Hum-8
which showed elevated total pigment levels compared to 2015, average TN levels in the
summer of 2016 were also higher than in summer 2015 (1.19 mg/L and 0.576 mg/L
respectively) and in 2017 and 2018 which showed the highest total pigment levels (44.9
and 50.7 ug/L) with associated TN levels of >1.20 mg N/L. It appears that the lack of a
significant spring opening allowed phytoplankton to build to bloom levels throughout the
upper tidal reaches in both 2017 and 2018 compared to prior years. Additionally, in
2016 at station Hum-7 which showed similar total pigment levels compared to 2015,
average TN levels in the summer of 2016 were nearly the same as in summer 2015
(0.674 mg/L and 0.621 mg/L respectively). In 2017 and more so in 2018, total pigment
levels at Hum-7 were noticeably higher (13.9 and 21.8 ug/L) than in 2016 and 2015 (5.9
and 7.1 ug/L respectively) and with associated higher TN levels in 2017 and 2018 of
0.789 and 0.889 mg N/L, respectively. In general, it appears that the water quality in
Hummock Pond does respond well to longer inlet openings as achieved in the spring of
2016 (18 days) and spring of 2015 (15 days). However as indicated by the elevated
30
2017 and 2018 nutrient and total pigment results, the pond is very sensitive to the
duration of openings. Further improvements are anticipated if openings can be made
longer than 18 days or loads to Hummock Pond reduced. It should be noted that each
consecutive year of good tidal exchanges lowers the overall TN level the following year
until a new equilibrium is reached (likely 3-5 years). This has been observed in
periodically opened ponds on Martha’s Vineyard (e.g. Edgartown Great Pond) and it
stems from the fact that lowering TN levels requires time to build back up from
watershed inputs and sediment recycling than if the TN levels remain high year around.
Table A - 2018 Minimum, Maximum and Average CHLA and Total Pigment values for
the closed ponds of Nantucket.
Table B - 2017 Minimum, Maximum and Average CHLA and Total Pigment values for
the closed ponds of Nantucket.
Table C - 2016 Minimum, Maximum and Average CHLA and Total Pigment values for
the closed ponds of Nantucket.
2018 min max avg min max avg
System CHLA CHLA CHLA Total Pig Total Pig Total Pig
(ug/L)(ug/L)(ug/L)(ug/L)(ug/L)(ug/L)
Miacomet Pond 0.14 151.81 20.92 8.13 153.58 27.85
Sesachacha Pond 1.33 24.06 10.57 1.36 28.35 13.58
Long Pond 5.87 11.37 9.25 8.72 16.09 11.19
Hummock Pond 3.35 77.26 16.71 6.86 80.37 22.06
2017 min max avg min max avg
System CHLA CHLA CHLA Total Pig Total Pig Total Pig
(ug/L)(ug/L)(ug/L)(ug/L)(ug/L)(ug/L)
Miacomet Pond 2.46 33.87 8.29 4.82 44.30 12.65
Sesachacha Pond 4.92 23.68 8.92 5.23 23.99 10.48
Long Pond 0.57 31.04 11.51 5.24 36.70 14.19
Hummock Pond 2.89 65.26 19.93 2.91 88.96 24.72
31
Table D - 2015 Minimum, Maximum and Average CHLA and Total Pigment values for
the ponds of Nantucket with limited or only periodic tidal exchange.
Figure 10. Average Total Pigment (Chlorophyll-a +Pheophytin) concentrations by station in the
Long Pond portion of the Madaket Harbor system during the summer 2018 sampling season
compared to 2010, 2012, 2013, 2014, 2015, 2016 and 2017.
min max avg min max avg
System CHLA CHLA CHLA Total Pig Total Pig Total Pig
(ug/L)(ug/L)(ug/L)(ug/L)(ug/L)(ug/L)
Miacomet Pond 2.88 43.05 11.82 5.44 58.35 15.52
Sesachacha Pond 2.92 10.51 5.60 3.54 10.54 6.68
Long Pond 1.52 6.80 4.14 2.55 9.67 6.12
Hummock Pond 0.86 44.86 5.11 1.62 46.18 7.52
min max avg
System CHLA CHLA CHLA
(ug/L)(ug/L)(ug/L)
Miacomet Pond 2.80 204.83 41.26
Sesachacha Pond 3.08 11.23 6.79
Long Pond 2.56 11.37 5.44
Hummock Pond 1.00 19.71 4.50
min max avg
System Total Pig Total Pig Total Pig
(ug/L)(ug/L)(ug/L)
Miacomet Pond 9.55 204.86 48.71
Sesachacha Pond 6.56 18.79 11.10
Long Pond 4.40 19.54 9.30
Hummock Pond 2.92 43.41 9.24
32
Figure 11. Average Total Pigment (Chlorophyll-a +Pheophytin) concentrations by station in the
seasonally opened Hummock Pond system, during the summer 2018 sampling season
compared to 2010, 2012, 2013, 2014, 2015, 2016 and 2017.
Figure 12. Average Total Pigment (Chlorophyll-a +Pheophytin) concentrations by station in the
Miacomet Pond system during the summer 2018 sampling season compared to 2010, 2012,
2013, 2014, 2015, 2016 and 2017. Miacomet Pond is not opened to the Atlantic Ocean and
now contains freshwater (<0.2 PSU).
33
Figure 13. Average Total Pigment (Chlorophyll-a +Pheophytin) concentrations by station in the
seasonally opened Sesachacha Pond system during the summer 2018 sampling season
compared to 2010, 2012, 2013, 2014, 2015, 2016 and 2017.
Average Total Nitrogen values for all of Hummock Pond (MEP TN threshold = 0.50
mg/L, HUM-3) were higher in 2018 than 2017 with a commensurate increase in total
phytoplankton pigment throughout the pond. By comparison, in 2016 total pigment
appeared slightly lower in the bottom half of the pond and slightly higher in the upper
half compared to 2015. Total nitrogen in the full main stem averaged 0.832 mg/L in
2018 and 0.932 mg/L in 2017 whereas in prior years [2016, 2015, 2014, 2013, 2012,
2010] average TN values were [0.797, 0.583, 0.715, 0.900, 0.923, 0.944 mg/L]
respectively. However, the pattern for Hummock Pond is somewhat deceptive given the
strong TN gradient from the upper station (Hum 7) and the lower stations (Hum 1 & 3).
The lower stations, most influenced by the breaches, showed the largest improvement
2014-2016, with 2016 showing the lowest TN levels to date approaching the TMDL
threshold level. The gradient was also seen in 2017 and 2018 (lower stations better
than upper stations), however, given the short breach, TN levels remained significantly
higher than in 2016 with the associated effect of high total pigment and chlorophyll
levels. This inter-annual variation follows the pattern of improved flushing observed in
fall 2014, 2015 and 2016 under effective openings, and decreased water quality under
the poor flushings from spring 2014 and spring 2017. Relative to the 2012-2018 and
2010 data sets, results indicate that within Hummock Pond, less so Long Pond and
Miacomet Pond, there is a general gradient of nutrient (N and inorganic P) and
chlorophyll concentrations from high levels in the upper, more enclosed and poorly
flushed reaches of the estuaries to lower concentrations closer to the outlets where
flushing is more effective (Figure 15,16). The gradient appears to be a bit flatter in 2016
for both Long Pond and Miacomet Pond but more pronounced in 2017 and 2018. Based
on average TN values in Hummock Pond, water quality in 2017 and 2018 appears lower
compared to 2016 and well above the nitrogen threshold needed for restoration.
34
In contrast, Miacomet Pond (No MEP threshold set) which has had no restoration
activities or openings in recent decades showed TN levels in 2018 (0.741 mg/L)
comparable to 2017 (0.711 mg/L) and 2016 (0.742 mg/L) and significantly lower TN
levels than in 2015 (1.203 mg/L) and the previous 4 years of monitoring [1.202, 0.982,
0.962, 0.919, 0.886 mg/L]. Not surprisingly, average total pigment values in 2018 (25.0
ug/L) were higher than 2017 and 2016 (14.11 and 14.10 ug/L respectively). It is not
clear what has caused the recent reductions (2017 and 2016), but as a freshwater
pond, Miacomet is highly influenced by freshwater inflows and may be responding to
lower freshwater inflows associated with the drought in 2016, but this is purely
speculative and would need site-specific confirmation. It should be noted that although
Miacomet Pond’s TN levels were observed to be lower in both 2018, 2017 and 2016
compared to previous years, the levels are still quite elevated and the pond is clearly
impaired by excess nutrients (N & P). The high levels of TN in these poorly flushed
estuaries clearly contrast with the levels of TN and pigment in Nantucket’s well flushed
estuaries (Nantucket and Madaket Harbors). The effect of reduced flushing is to
increase the sensitivity of an estuary to nutrient inputs as water exchange rates are
diminished.
In addition to TN, the measured TP levels in Miacomet Pond in 2018 (MP-1: 60 ug/L;
MP-2 61 ug/L; MP-3: 103 ug/L) were higher than in 2015 and 2016 which were also
similarly high (MP-1: 45-85 ug/L; MP-2 68-80 ug/L; MP-3: 65-136 ug/L; Tables 3a &
3c). If Miacomet Pond is to be managed as a freshwater pond then phosphorus needs
to be considered (with nitrogen) as a concern. Since no fresh pond or lake nutrient
TMDLs have been developed on Cape Cod or Nantucket, SMAST’s 2001 survey of 190
lakes and ponds on Cape Cod was used by the Cape Cod Commission to develop
potential region-specific nutrient thresholds.3 This review used an EPA method that
relies on a statistical review of the available data within an eco-region to develop the
thresholds.4 This review suggested a target TP concentration range for Cape Cod
ponds between 7.5 and 10 µg/L to sustain high quality pond habitats. Potential target
threshold ranges were also developed for total nitrogen (0.16 to 0.31 mg/L), and
chlorophyll-a (1.0 to 1.7 µg/L). These concentrations closely approximated the EPA
eco-region reference criteria available at the time for the region.5 These Cape Cod-
specific thresholds can be used as guidance targets for Miacomet Pond, they have not
been formally adopted as regulatory standards by MassDEP. However, it is clear even
from the limited TP data available that phosphorus levels within Miacomet Pond are
consistent with an impaired freshwater pond, which is supported by the high TN and
chlorophyll-a levels.
Miacomet Pond in 2017 and 2018 as in 2016-2014 likely had phytoplankton production
(e.g. chlorophyll-a) stimulated by both N and P inputs as pond salinities declined to
present levels. As TP and PO4 samples were collected in parallel with the nitrogen
fractions in the 2018-2014 surveys of Miacomet Pond, it was possible to assess
eutrophication from N and P. N/P ratios can be compared to the idealized Redfield
3 Eichner, E.M., T.C. Cambareri, G. Belfit, D. McCaffery, S. Michaud, and B. Smith. 2003. Cape Cod Pond and Lake Atlas. Cape Cod
Commission. Barnstable, MA.
4 U.S. Environmental Protection Agency. 2000. Nutrient Criteria Technical Guidance Manual: Lakes and Reservoirs. First Edition. EPA-822-
B00-001. US Environmental Protection Agency, Office of Water, Office of Science and Technology. Washington, DC.
5 U.S. Environmental Protection Agency. 2001. Ambient Water Quality Criteria Recommendations. Information Supporting the
Development of State and Tribal Nutrient Criteria for Lakes and Reservoirs in Nutrient Ecoregion XIV. EPA 822-B-01-011. US
Environmental Protection Agency, Office of Water, Office of Science and Technology, Health and Ecological Criteria Division.
Washington, DC.
35
Ratios (C:N:P, 106:16:1) to get a first approximation of the degree to which N or P
maybe structuring the pond. Interestingly, particulate C/N ratios remain relative
consistent from the head to the lowest basin of the pond closest to the ocean (MP3 -
MP1 - MP2, C/N ratio in 2017 of 7.5, 7.7, 8.4, in 2016 of 7.3, 6.9, 8.6 and in 2015 6.5,
6.8, 6.5 respectively, Redfield C/N ratio is 6.62). This supports the contention that
phytoplankton comprise almost all of the particulate matter in the pond. The nutrient
data showed significant variation between the pond basins, with total N/P ratios lower at
the head and increasing to the middle and lower portions (MP3 to MP1 - MP2, for a total
N/P ratio in 2018 of 12.1, 29.0, 31.3 were lower at the head, but similar within the main
basin compared to 2017 of 20.1, 35.4, 40.9, in 2016 of 26.8, 37.9, 21.8, and 2018 was
very similar to 2015 ratios at these stations of 16.9, 36.9, 34.4 respectively, Redfield
N/P ratio is 16). In freshwater basins, Ratios significantly greater than 16 (i.e. >20)
indicate that phosphorus additions likely result in increased eutrophication and that
Phosphorus should be a focus of pond management. This is the case throughout
Miacomet Pond in 2018, 2017 and 2016, for the middle and lower pond. It is also
important to note that orthophosphate concentration are quite low in the main basin
(MP-1, MP-2) generally <0.2 uM, such that adding phosphorus to this basin in mid
summer would likely stimulate phytoplankton growth. In contrast, the upper station
(MP-3 generally supports 2x-3x higher phosphate levels. It is likely that regions of the
pond may be sensitive to both nitrogen and phosphorus, such that overall both nutrients
need to be monitored and considered for management of Miacomet Pond, although
phosphorus management is clearly needed at this time.
As previously recommended, to refine this approximation of the limiting nutrient for Miacomet
Pond, nutrient ratios from the monitoring effort should be coupled to controlled bioassays
(bottle tests, mesocosms) with different levels of P and N amendments to the natural
phytoplankton community. These types of bioassays were employed by the Coastal Systems
Program for an assessment of other low salinity ponds, Oyster Pond in Falmouth and
Cockeast Pond in Westport, specifically to better determine the degree of N or P limitation for
nutrient management purposes. Comparison of algal bioassay results and chemical nutrient
concentrations in lakes has suggested that a mass N:P ratio above 20 indicates P limitation, a
ratio below 10 indicates N limitation and values between 10 and 20 indicate that either of the
nutrients may be limiting." (Petri Ekholm, Finnish Environment Institute, 2008). That there is
variation in N/P ratios in the different basins of the pond suggests that some regions could be
either N limited or P limited (or both). A more detailed examination of N and P cycling is
warranted to ascertain which is playing a bigger role in the nutrient cycling of the pond system
as a whole. At present, this pond continues to appear to have shifted from a eutrophic
brackish water system to a eutrophic freshwater ecosystem and should potentially be
managed as such, taking into consideration which nutrient is dominant (N vs. P). However,
management must include that periodic overwash from storms could upset the ecological
balance of this system if it were managed purely as a freshwater system. All of the estuarine
stations in Nantucket’s estuaries are clearly nitrogen limited, based upon various assessments
including the MEP.
36
Table E - Below shows various nitrogen to phosphorous ratios from Miacomet Pond
during the summer 2018 sampling season.
Table F - Below shows various nitrogen to phosphorous ratios from Miacomet Pond
during the summer 2017 sampling season.
Table G - Below shows various nitrogen to phosphorous ratios from Miacomet Pond
during the summer 2016 sampling season.
Table H - below shows various nitrogen to phosphorous ratios from Miacomet Pond
during the summer 2015 sampling season.
Station Id.N/P PC/PN DIN/DIP TN/TP
(2018)organic particulate inorganic total
MP-3 25.7 7.2 2.1 12.1
MP-1 34.7 6.3 7.5 29.0
MP-2 33.1 6.1 17.1 31.3
Station Id.N/P PC/PN DIN/DIP TN/TP
(2017)organic particulate inorganic total
MP-3 34.7 7.5 3.4 20.1
MP-1 39.6 7.7 7.0 35.4
MP-2 43.9 8.4 12.4 40.9
Station Id N/P PC/PN DIN/DIP TN/TP
organic particulate inorganic total
MP-3 16.9 6.5 10.2 16.1
MP-1 36.9 6.8 10.3 34.3
MP-2 34.4 6.5 13.1 32.3
Station Id. N/P PC/PN DIN/DIP TN/TP
(2016) organic particulate inorganic total
MP-3 33.4 7.3 2.9 26.8
MP-1 41.2 6.9 5.8 37.9
MP-2 21.8 8.6 8.8 21.8
37
Similar to observations of Hummock Pond, Total Nitrogen values also show inter-annual
variations in Long Pond (MEP secondary threshold, Long Pond basin average 0.80
mg/L). TN levels in 2018 (0.587 mg/L) were lower than in 2017 (0.787 mg/L) but similar
to 2015 and 2016; 2016-2012 and 2010 of 0.640, 0.677, 1.14, 0.795, 0.94,1.75 mg/L. In
Sesachacha Pond (MEP threshold < 0.60 mg/L, SES-1) 2018 (0.752 mg N/L) was lower
than 2017 (0.882 mg N/L) but within the range of 2016-2012 and 2010: 1.000, 0.904,
0.922, 0.669, 0.704, 0.639 mg/L. Like Hummock and Miacomet Ponds, Long Pond and
Sesachacha Ponds are poorly flushed with Miacomet Pond not having been opened in
over a decade and Long Pond having a poor hydraulic connection to Hither Creek /
Madaket Harbor via Madaket Ditch. In the case of Sesachacha Pond, the TN levels
also appear to be related to the success of the periodic openings. The similar TN levels
in 2017, 2016 and 2015 (0.960, 1.00 mg/L and 0.904 mg/L respectively) are predicted
from the similar Spring opening durations (5 days Spring 2015, 3 days Spring 2016, 7
days Spring 2017) and are higher than the previous years which had better openings
and associated lower subsequent TN levels (<0.704 mg/L). It is worth noting that the
very high historic levels (1.20 mg/L) and 2010 levels were under less robust opening
conditions, prior to the Town’s new awareness of the importance of openings as a pond
management tool. It should be noted that Sesachacha Pond TN levels in 2018, 2017
and 2016 (and 2015) are still lower than during the MEP assessment and suggest that
achieving the TMDL may be possible by refined openings, saving infrastructure costs.
Additionally, it appears nutrient related water quality is worsening as a function 2014-
2017 poor openings with some improvement in 2018. As previously mentioned above,
in the case of Sesachacha Pond, where openings are through a barrier beach subject to
very active coastal processes, if openings cannot be made more effective (e.g. like
2010, 2012, 2013), it may be necessary to consider nutrient load reducing strategies in
the watershed or in situ processes to improving water quality, such as use of oysters to
lower TN levels, as is being considered by a number of towns on Cape Cod (Falmouth,
Orleans, Mashpee) as well as across Buzzards Bay (Westport). Average TN levels in
all 4 ponds are significantly higher than average values in the “offshore” stations NAN 4
and MH4 which average 0.288 [0.283, 0.297, 0.277, 0.317, 0.344, 0.302] and 0.306
[0.219, 0.328, 0.254, 0.278, 0.297, 0.285] mg/L, respectively (Tables 3a, 3b, 3c, 3d,
3e,3f, 3g, Figures 1, 2). It should be noted that the average offshore TN concentration
for station MH4 is 0.295 mg/L if the 8/5/2015 sampling date (TN concentration = 0.427
mg/L) is not included in the calculation. It appears that sample data for that one
sampling date is aberrant, which is supported by statistical analysis of the complete
data set (2010-2018).
Long Pond (MEP secondary threshold = 0.80 mg/L) showed significantly lower TN
levels (~40%) in 2018 and 2012 versus 2010. Levels at Station 5 declined from 2012 to
2013 and held steady or improved in 2013, however there was an increase in average
TN levels from 2013 to 2014 at station 5 (1.48 mg/L in 2014 vs. ~0.70 mg/L in 2013).
TN concentrations at station 5 returned to 2013 levels in 2015 (0.697 mg/L). In 2016
TN concentrations at station 5 declined again reaching the lowest level on record, 0.650
mg/L. In 2018, data indicate that TN levels declined to 0.587 mg/L, however, the
duration of this shift in TN levels is unknown at present. The general decline from
historic levels, 2010 to 2016 in TN levels at station 5 needs to be tracked closely by the
monitoring program, as MEP modeling suggests that conditions will improve
significantly in Long Pond as the landfill TN load diminishes. Similarly, Station 6 also
shows declining TN levels from historic to 2010 to 2016 samplings. Station 6 TN
concentrations in 2016 declined to the lowest on record, 0.629 mg/L even lower than
38
2015, 0.656 mg/L, with 2014 being 0.788 mg/L and historic levels being 0.84 mg/L. In
2017, TN levels at station LONG6 increased to 0.712 mg/L, consistent with the
observed increase at station LONG5. Based on the previous declines in TN
concentrations observed in 2016 and 2015 and the increase and then decrease at both
stations in 2017 and 2018, it appears that there is inter-annual variation that must be
accounted for in Long Pond. Continued monitoring of stations 5 and 6 is warranted to
confirm the downward trend in TN concentrations observed in past years. Overall, the
monitoring results, both long term and over recent years, show a clear decline in TN
from historic to 2018 levels, with TN levels at both stations in both 2015 and 2016 and
2018 being less than half of previous observations. However, the slight increase
measured in 2017 should be tracked and more specific investigation into the nutrient
load reductions related to work at the landfill is being undertaken through use of the
MEP modeling tool to determine if the general downward trend is landfill related.
The long-term lowering of the TN levels, particularly at station 6, is consistent with on-
going Town activities at the landfill (mining and capping), as 2018, 2016, 2015, 2014
and 2013 TN levels follow a downward trend and chlorophyll-a levels in Long Pond are
significantly lower than in 2010 and 2012 and generally similar to what was measured in
2013, 2014 and 2015 but with 2016 levels being the lowest on record. While TN levels
measured in 2017 did appear higher and at odds with the decreases measured over the
past few years, the TN decline was again seen in the 2018 data, supporting the longer
term TN reduction. Therefore, the monitoring program should continue to track the
improvements in water quality at station 5 and 6 and the Town may want to continue to
measure nutrient water quality in the wells down gradient of the land fill (as initiated by
the Town DPW assisted by CDM-Smith) to better quantify any continuing positive effect
the land fill actions maybe having on Long Pond and to better project the potential
magnitude of the reduction in load and the time required until the full effect is realized.
Additionally, at present the MEP water quality model is being rerun with the new landfill
loads based on all the upgrades completed to date to see how the modeling results
match the water quality observations from the past few years. Results of updated
scenario runs using the MEP developed modeling tool and new loads will support
adaptive management approaches ultimately steering decision makers to the most cost
effective solutions for restoration.
As in all previous years, in Sesachacha Pond (MEP threshold <0.60 mg/L, SES-1),
there is no noticeable nutrient or chlorophyll gradient among any of the 4 Stations
(Figure 13 and 15, Tables 3a,b,c,d,e,f,g). The well horizontally mixed nature of this salt
pond results from it only having periodic tidal exchange such that it operates more like a
kettle pond than a tidal estuary. However, it should be noted that while TN and
chlorophyll-a concentrations in Sesachacha Pond where generally higher in 2014
compared to 2013, TN levels in 2015 remained high (0.904 mg/L and 0.922 mg/L
respectively), which continued through the 2016 field season. The slight rise in TN in
2016 (1.00 mg/L) is consistent with its limited opening. TN levels in 2017 appeared to
drop from 2016 levels (0.884 mg/L vs. 1.00 mg/L) and again in 2018 to 0.752 mg N/L.
This does not seem unusual considering the duration of the spring 2017 opening
compared to the spring 2016 opening. The spring 2017 opening lasted 7 days whereas
the spring 2016 opening was only 3 days in duration. The spring 2018 opening of 3
days did lower TN levels slightly 2017 levels, however, average chlorophyll levels in
2018 were higher than past years, likely due to small window for exchange with low
nutrient Atlantic Ocean water. It is Interesting to note that while total pigment in 2015
39
was higher than what was observed in 2014 (11.07 ug/L versus 6.37 ug/L respectively),
TN levels were similar in both years, and the slightly higher TN in 2016 supported a
similar total pigment as 2014 (6.56 ug/L and 6.37 ug/L respectively). TN levels while
lower in 2018 were similar to 2017, average total pigment levels (13.9 and 10.6 ug/L)
compared to 2016 (5.4 ug/L), but similar to what was observed in 2015 (11.07 ug/L).
Given the diverse factors which can alter pigment levels (wind, light, temperature,
nutrients, water clarity) the difference is similar to that seen in other systems throughout
the region. That there was a noticeable increase from 2013 to 2014 and consistency
between 2014, 2015, 2016 and 2018 with a temporary increase in 2017 is good reason
to continue regular monitoring of the system, particularly to determine changes in the
effectiveness of annual pond openings that are the likely driver for increased or
decreased water quality in a given year. However, TN levels remain well above the
nitrogen threshold in the TMDL, and the 2014, 2015 and 2016 TN increase is a cause
for concern, particularly after the few prior years of much lower TN levels (~0.6 mg/L). It
appears the short duration spring openings in 2015 and 2016 are having a negative
effect on pond water quality, however the longer (7-day) opening and the associated
reduction in TN concentrations is a clear sign that longer openings achievable under the
right conditions (wind direction, wind speed, wave state, lunar phase, pond stage) are
effective for reducing nutrient levels in the pond.
Consistent with previous years monitoring results, in 2017 and 2018 Madaket Harbor
(MEP threshold 0.45 mg/L, MH-1: Hither Creek) showed a clear nitrogen gradient (and
associated metrics) from Station 1 (0.57 and 0.41 mg/L) in Hither Creek (which receives
discharge from Long Pond via Madaket Ditch), and is relatively poorly flushed, out to
Station 2 (0.39 and 0.29 mg/L) in the Harbor, with further decreases out to the off-shore
Station 4 (0.20 mg/L, Figure 9 and 15, Table 3a). In 2018, the TN levels continued their
decline from prior years and it appears that this system may have achieved its TMDL
target set by MassDEP/EPA. Similarly, in Nantucket Harbor in 2018, there is a very
small nutrient gradient from Wauwinet at the Head of the Harbor (Nan-3, 0.33 mg/L) and
the more enclosed Polpis stations out to the entrance at Stations 8 (0.25 mg/L) and 4
(0.19 mg/L). There is also a total chlorophyll gradient with the highest concentrations at
the 2 Polpis Stations (5 and 6, 7.2 and 8.6 ug/L respectively) and Wauwinet basin (6.7
ug/L), decreasing in the main Harbor and out to the off-shore Station 4 (3.3 ug/L).
These levels within the main open basins are indicative of high quality habitat and
nutrient related water quality.
Average 2018 [2017-2013, 2012, 2010] TN level in Madaket Harbor (Stations 1-3, not
including Station 4, offshore) was 0.308 [0.433, 0.343, 0.422, 0.390, 0.404, 0.485,
0.462] mg/L, compared to the off-shore Station 4, 0.181, [306, 0.219, 0.328, 0.254,
0.278, 0.297, 0.285] mg/L. As mentioned above, due to the lack of a significant
temporal trend, the best estimate of the offshore TN concentration for station MH4 is the
average of all years (2010 to 2017, 0.281 mg/L).
Average 2018 TN in Nantucket Harbor {MEP threshold = 0.35 mg/L at NAN-2A and
0.355 at NAN-6} (all stations except Station 4, offshore) remain quite low averaging
0293 in 2018 and 0.353 mg/L in 2017 compared to 2010, 2012, 2013, 2014, 2015,
2016, with the offshore boundary station 4 averaging only 0.288 mg/L in 2017, slightly
lower compared to offshore Madaket Harbor station MH-4 at 0.306 mg/L (Tables 3a,
3b). It should be noted that the 2010 value includes station NAN-8 (the cut) whereas
the 2017, 2016, 2015, 2014, 2013 and 2012 value includes station NAN-8N which was
40
relocated into the Town Basin within the Harbor (refer to Figure 2 for station location).
Additionally, as specified in the nutrient TMDL developed by the MassDEP based on the
MEP nutrient threshold analysis, an additional monitoring station was added in head of
Nantucket Harbor (NAN-2A) to represent the water quality at the MEP sentinel station.
In 2018 and 2017, the TN concentration at station NAN-2A was 0.337 and 0.377,
respectively. In 2016 the TN level at station NAN-2A was 0.415 mg/L. The MEP TN
threshold concentration were exceeded at these sentinel locations, 0.350 versus 0.337
and 0.377 mg/L, and for the sentinel station in Polpis Harbor (NAN-6) 0.355 mg/L
versus 2018/2017 TN level = 0.327/0.405 mg/L. Generally, conditions in Nantucket
Harbor were not significantly different in 2018 and 2017 compared to 2016, but did tend
to be lower overall.
Estuarine Temporal Analysis: As the Nantucket Water Quality Program has collected
8 years of field data, it is possible to begin assessing long term trends. While this
usually requires a decade of monitoring, we can conduct an initial analysis on “whole
estuary results”. In this analysis all of the stations and events are averaged to yield an
overall TN or total chlorophyll a value for an estuary for each year so that the complete
time series can be evaluated. This approach can yield new information when examining
factors that affect entire estuaries, like increases or decreases in nitrogen loading or
changes in tidal flushing. Smaller single year events, e.g. rainfall, show up as
variability, as they are not long-term trends.
Temporal analysis of Hummock Pond underscores the inter-annual variability within its
main basin for key water quality indicators, TN and total chlorophyll-a, due primarily to
the amount of flushing achieved through its spring opening (Figure 14a). While the
openings in 2014-2016 brought the overall TN levels significantly down from prior years,
the spring 2017 and 2018 openings were insufficient to maintain these lower levels and
TN level rose to the prior highs of 2014-2016 (note 2018 opening was slightly more
effective than 2017). As such there is no consistent trend, but the results clearly
indicate that TN levels can be lowered significantly in this basin through pond openings,
when “successful”, almost to levels restorative of currently impaired habitats. However,
given the variability in openings the Town may consider a hybrid approach of openings
plus either in pond nitrogen reduction (shellfish) or watershed source control for long-
term restoration of this system.
As stated above, Sesachacha Pond, like Hummock Pond, has its water quality primarily
controlled by the amount of flushing achieved during its spring openings. The variability
introduced by the quality of openings makes temporal analysis difficult. However, it
appears that Sesachacha Pond TN levels have clearly increased in recent monitoring
years (Figure 14b). The increase is significant (t test, p<0.05) with the initial years
2010-2013 (TN=0.671 mg/L) significantly lower than 2014-2017 (TN=0.933 mg/L), with
the groupings determined by the quality of the openings. While the pond during this
period moved toward historic low water quality levels, the high quality openings in 2010-
2013 indicate that pond openings can play a primary role in restoring water and habitat
quality within the pond (threshold = 0.600 mg/L), although this may have to be done in
concert with other nitrogen management alternatives, e.g. shellfish, source reduction,
etc. During 2017 nitrogen levels once again began to decline over the previous 2 years
and further declined in 2018 to levels near 2010 (0.752 vs 0.704 mg N/L) again
indicating that restoration of this system should probably include a tidal flushing
41
component to reduce infrastructure costs and to ensure that this provides productive
estuarine habitat.
In contrast to Hummock Pond and Sesachacha Pond, Long Pond is open to tidal
exchange, although somewhat restricted as seen in its mean salinity (2017 = 14 PSU
and 2018 16 PSU; mean stations 5 & 6). Madaket Ditch provides a conduit for outflow
of nutrient rich water from Long Pond and inflowing low nitrogen water from Madaket
Harbor. Early on, the Nantucket Water Quality Monitoring Program reported a decline
in TN levels potentially resulting from Town improvements to the landfill in the Long
Pond watershed. Initially, it was not clear if the observed decline 2010-2013 would be
sustained, continue to decline or return to previous (MEP) levels. It now appears that
TN levels have declined significantly with 2018 being the lowest on record (0.59 mg
N/L) and may be stabilizing at a lower level, around 0.60 mg N/L, Figure 14c). However
due to inter-annual variations which may be related to on-going activities at the landfill
and/or ecological transitions within the pond itself, it is not yet clear what the “new”
steady state TN level will be. However, continued monitoring should clarify this latter
point within a few years, unless new nitrogen sources or sinks develop within the
watershed.
The large estuarine basins of Madaket Harbor and Nantucket Harbor both support high
quality habitats consistent with their low TN and chlorophyll-a levels. The nearshore
region of Madaket Harbor (stations 1-3) is the recipient for ebbing waters from Long
Pond via Madaket Ditch. Temporal analysis indicates that TN levels at these nearshore
stations has declined slightly over the monitoring period (Figure 14d). While there is
some inter-annual variation in TN levels, the decline is statistically significant. At this
point the only explanation available for this observed decline is that the TN load to
Madaket Harbor from Long Pond has been decreasing. As more information from the
landfill has become available the Town has decided to re-run the MEP Watershed-
Embayment Model for this system as previously mentioned above to verify the expected
improvements to Hither Creek (sentinel station) and Madaket Harbor, as well as Long
Pond itself. At present, it is important to determine the new steady state TN level in
Long Pond, as it appears to be approaching the level set in the MassDEP/USEPA
TMDL for this system.
Similarly, the main basins of Nantucket Harbor are also showing a possible temporal
decline in TN, although the amount is obscured by the inter-annual variability (r2=0.30)
and the very small changes (Figure 14e). At present, the time-series changes cannot
be demonstrated statistically and therefore only indicate that analysis should continue.
However, it does not appear that TN levels are decreasing. It should be noted that only
a very small TN reduction was anticipated from the reconstruction of the jetties, but as
additional planned sewering is undertaken, it should be possible to detect the TN
reduction. As stated above, this temporal analysis is preliminary and is being
undertaken to guide future analysis.
42
Figure 14a. Hummock Pond main basin annual averages for TN and total chlorophyll a from
2010, 2012-2017 (shown as year 0, 2, 3, 4, 5, 6, 7). No significant temporal trends were
detected. Does not include the semi-isolated Head of Hummock Pond.
Figure 14b. Sesachacha main basin annual averages for TN and total chlorophyll a from 2010,
2012-2017 (shown as year 0, 2, 3, 4, 5, 6, 7). Total nitrogen appears to have been increasing
over the monitoring period as openings have declined. 2010-2013 (TN=0.671 mg/L) is
significantly (p<0.05) lower than 2014-2017 (TN=0.933 mg/L).
0.0
5.0
10.0
15.0
20.0
25.0
30.0
35.0
0.000
0.100
0.200
0.300
0.400
0.500
0.600
0.700
0.800
0.900
1.000
0 2 4 6 8 Total Chlorophyll a (ug/L)Total Nitrogen (mg/L)Hummock Pond 2010-2018
TN mg/L T-pig ug/L
y = 0.0474x + 0.6376
R² = 0.60
0.00
0.20
0.40
0.60
0.80
1.00
1.20
0.0
2.0
4.0
6.0
8.0
10.0
12.0
14.0
0 2 4 6 8 Total Nitrogen (mg/L)Total Chlorophyll a (ug/L)Sesachacha Pond Sta 1-4: 2010-18
43
Figure 14c. Long Pond main basin annual averages for TN and total chlorophyll a from 2010,
2012-2017 (shown as year 0, 2, 3, 4, 5, 6, 7). Total nitrogen has declined over the monitoring
period and appears to be stabilizing.
Figure 14d. Nearshore Madaket Harbor main basins annual averages for TN and total
chlorophyll a from 2010, 2012-2017 (shown as year 0, 2, 3, 4, 5, 6, 7). Total nitrogen appears
to have been declining over the monitoring period. While the trend is significant (p<0.05), the
variability makes an accurate determination of average annual decline difficult in this initial
analysis. The offshore station is not included.
y = 0.0207x2 -0.2809x + 1.6135
R² = 0.7882
0.00
0.20
0.40
0.60
0.80
1.00
1.20
1.40
1.60
1.80
2.00
0.0
5.0
10.0
15.0
20.0
25.0
0 2 4 6 8 Total Nitrogen (mg/L)Total Chlorophyll a (ug/L)Long Pond 2010 -2018
T-pig ug/L
TN mg/L
y = -0.0167x + 0.4773
R² = 0.59
0.00
0.10
0.20
0.30
0.40
0.50
0.60
0.0
2.0
4.0
6.0
8.0
10.0
12.0
0 2 4 6 8 Total Nitrogen (mg/L)Total Chlorophyll a (ug/L)Madaket Hbr Sta 1-3: 2010 -2018
44
Figure 14e. Nantucket Harbor main basins annual averages for TN and total chlorophyll a from
2010, 2012-2017 (shown as year 0, 2, 3, 4, 5, 6, 7). Total nitrogen appears to have been
declining over the monitoring period, but the variability makes determination of the magnitude
difficult at this time. The variability and small potential decline can be seen in the low R2. The
offshore station is not included.
Streams: Stream flow data has is not currently available for 2018 field season, but will
be included at the appropriate time. Stream sampling in 2017 followed sampling
completed in 2016 with the addition of one stream sampling location (WPH OUTLET,
Figure 6). WPH Outlet was added by the Town of Nantucket as it is thought that a
portion of the flow from the up-gradient bogs is discharged to West Polpis Harbor as
depicted in Figure 6a. 2016 stream sampling locations were reduced from 6 stream
locations to 3 (STA. 4, 4A and 6B), all of which discharge to Polpis Harbor. Stations 4
and 6B represent two distinct surface water inflows to Polpis Harbor with flow passing
station 6B entering West Polpis Harbor and flow passing station 4 going to East Polpis
Harbor from the up-gradient bogs, with the above mentioned caveat regarding station
WPH OUTLET which may be directing a bit of cranberry bog flow to West Polpis
Harbor. Station 4A (selected by the Conservation Foundation) is located up-gradient of
station 4 and captures nutrient conditions prior to influence from a network of cranberry
bogs.
TN concentrations at the three discharge points measured in 2017 (stations 6B, WPH
OUTLET, 4) were relatively high and consistent (1.107 mg/L, 1.037 mg/L and 1.021
mg/L respectively). By comparison, the TN levels in the 2 streams to Polpis Harbor
sampled in 2016 ranged from 0.856 mg/L in Stream 4 to 0.922 mg/L in Stream 6B
(Table 3a). In spite of the high TN concentrations in these 2 streams and the TN loads
that these streams transport to Polpis Harbor, tidal flushing and dilution with lower
concentration Nantucket Harbor waters is sufficient to maintain TN levels in the main
body of Nantucket Harbor at relatively low levels (Table 3a,b,c,d,e,f,g; Figure 6, 6a).
The 2016 stream sampling sites were a subset of the streams sampled in 2010 with the
results coupled with 2017 data and discussed below. It should be noted that the stream
y = -0.0073x + 0.3837
R² = 0.303
0.00
0.05
0.10
0.15
0.20
0.25
0.30
0.35
0.40
0.45
0.0
1.0
2.0
3.0
4.0
5.0
6.0
7.0
8.0
0 2 4 6 8 Total Nitrogen (mg/L)Total Chlorophyll a (ug/L)Nantucket Hbr Sta 1-7: 2010-18
45
stations were not sampled in 2012, 2013 or 2014, however, with increasing interest in
lowering TN concentrations in Polpis Harbor, in 2015 it was decided to re-establish
sampling of streams discharging to this tributary sub-embayment and continue sampling
these sites with the idea that in the future a detailed evaluation of stream related flows
and loads to east and west Polpis Harbor would warranted.
Average 2017 [2016, 2015, 2014, 2013, 2012, 2010] TN concentrations in East Polpis
Harbor, 0.405 [0.400, 0.404, 0.378, 0.401, 0.438, 0.484] mg/L and West Polpis Harbor
0.429 [0.420, 0.422, 0.389, 0.385, 0.431, 0.419] appear to have been very stable from
2017-2012. These basins are fed by the high TN levels in Streams 4, WPH OUTLET
and 6B and diffuse groundwater inflows and support TN levels slightly higher than the
levels in the main Harbor, but still significantly lower than the levels in the streams
(Table 2a, Figure 6, 6a). It should be noted that the two stations in Polpis Harbor (NAN-
5 {Polpis west} and NAN-6 {Polpis east}) do show essentially the same TN
concentration compared to levels observed in 2016 and 2015. TN levels remain above
the nitrogen threshold for these basins, although total pigment was still relatively low in
2017 and similar to levels measured in 2016. Total pigment at Polpis Station NAN-5
was slightly lower in 2017 compared to 2016 (4.82 ug/L vs. 5.80 ug/L) and levels at
NAN-6 were slightly higher in 2017 compared to 2016 (6.51 ug/L vs. 4.61 ug/L). These
values are consistent with the nearly equal TN concentrations observed in 2017 and
2016. Chlorophyll levels in 2015 were higher than 2014 possibly reflecting the slightly
higher TN and warmer summer conditions in 2015 compared to 2014. Overall, TN
concentration in Nantucket Harbor was the same in 2017 (0.353 mg/L) compared to
2016 and slightly lower in 2016 (0.354 mg/L) compared to 2015 (0.381 mg/L) and
slightly higher compared to summer 2014 (0.324 mg/L). As such it is important to
continue summer water quality monitoring and watershed based nutrient management
and to provide a multi-year base for determining TMDL compliance as management
actions are being implemented. Evaluation of the streams should be continued keeping
stream volumetric flow and stream sampling such that nitrogen loads to Polpis Harbor
can be monitored and related to the Polpis Harbor TN levels. Determining the coupling
of stream inputs to Harbor TN levels may support development of a nitrogen
management alternative for this basins. However, given the complexity of flow from the
bogs seemingly split between east Polpis and west Polpis Harbor, a more detailed study
of this surfacewater flow systems and its associated loads might be needed to refine
any potential management action.
Stream sampling in 2015, 2016 and 2017 included both nitrogen concentration and flow
measurements and was included in the overall monitoring program to determine
linkages, as they may exist, between stream loads and Polpis Harbor TN levels,
particularly as related to the MEP TN threshold in Polpis Harbor (NAN-6 is considered
the MEP sentinel station, with a TN threshold concentration of 0.355 mg/L for
restoration). In 2017, samples were collected from 4 stations (stations 6B, WPH
OUTLET, 4, 4A) on two distinct streams flowing into different parts of Polpis Harbor
(e.g. east vs. west). This differs slightly from 2016 when samples were collected from a
total of 3 stations in 2 streams (ST4, ST4A, ST6B) but in 2015 the same stations (ST4,
ST6B) were sampled along with ST3 to gauge TN load discharging to Polpis Harbor. In
2017, station WPH OUTLET was added because it was suspected that a portion of the
flow from upgradient cranberry bogs was splitting towards west Polpis Harbor as
opposed to passing by station 4 and all entering east Polpis Harbor. In 2016, ST3 was
replaced by ST4A (upgradient of ST4) because there was little flow at ST3 in 2015 and
46
no measureable flow in the summer of 2016 (though not checked consistently by the
Town in 2016). Sampling at station 4A was continued in 2017, however, there is a
possibility that this maybe discontinued in 2018 due to the limited flow passing through
that stream sampling location. As in 2016, stream sampling in 2017 showed high TN
concentrations at stations 4 and 4A (1.021 mg/L and 0.984 mg/L respectively) and
higher than the same stations in 2016. By comparison, stream sampling in 2016
showed high TN concentrations at ST4 and 4A (0.856 mg/L and 0.776 mg/L
respectively) but were lower than in 2015 (ST4 in 2015 = 1.060 mg/L), based on data
presented in Table 2a,b,c. Interestingly, stream sampling site ST4 and ST6B were
sampled once (June) in 2010 and showed TN concentrations of 1.200 and 2.139 mg/L
respectively. The 2010 concentrations were consistent with the high concentrations
observed in 2015 but in 2016 TN levels at both these stations (4 and 6B) were similar
(0.856 mg/L and 0.922 mg/L) and lower than in 2015 or 2010. Similarly, in 2017 TN
levels at both these stations (4 and 6B) were essentially the same (1.021 mg/L and
1.107 mg/L respectively). It should be noted that TN concentrations at WPH OUTLET
were similar to measured concentrations at station 4, as would be expected (1.037 mg/L
vs. 1.021 mg/L) since the flow passing WPH OUTLET is supposedly from the same up-
gradient source, the cranberry bogs. The variation in TN levels from year to year may
be associated with a combination of changes in long-term groundwater variations as
well as cranberry bog management and warrants continued monitoring of stream flow
and nutrient concentrations discharging to Polpis Harbor. Management of these flows
and nutrient loads may provide a non-infrastructure approach to achieving the
MassDEP/USEPA TMDL TN threshold for Polpis Harbor at the sentinel station (NAN-6).
By measuring both the nutrient concentrations and the volumetric discharge the nutrient
load can be determined. As in the previous year, Town of Nantucket staff measured
the volumetric flow of water flowing at each sampling location in parallel with the water
quality sample collection during the summer 2017 field season. The Town provided to
CSP the critical stream flow values (m3/d) to be coupled with the parallel measurements
of total nitrogen concentration data to calculate TN load (kg/day) from these streams to
Polpis Harbor in summer 2017. The flow determined for each sampling day was then
used to determine load for a representative month.
Combining the high TN concentrations with relatively large flows measured in 2017 at
ST4, WPH OUTLET and ST6B, it is clear that a large TN load is being transported to
Polpis Harbor on a monthly basis, if there is sufficient flow. For the period June-
October, the load passing through sampling location 4, WPH OUTLET and 6B was
calculated to be 198 kg, 152 kg and 156kg respectively (based on values presented in
Table G). It is important to note that given some of the large loads presented for winter
and spring sampling dates as opposed to the lower loads during the summer when
rainfall is typically much lower than in the winter and spring, a more robust quantification
of flows and loads is warranted given the potential influence of these discharges on the
sentinel station in Polpis Harbor. Given this first approximation of the TN loads entering
Polpis Harbor via streams, it would clearly be worth continuing measuring flow and
nitrogen sampling in coming years of monitoring, particularly since flows and loads in
2017 and 2016 appeared higher than in 2015. A perfect comparison is difficult as the
sampling periods were not exactly the same in these initial years.
47
Table G. 2017 flows and nitrogen and phosphorus loads determined for two streams at
sampling stations 4 and 6B. Station 4A is upgradient of station 4 in the same stream.
Date Sample ID Measured TN Load TN Load TP Load TP Load Representative
Flow Month
(m3/d)(kg/day)(kg/month)(kg/day)(kg/month)
2/8/2017 ST4 343 0.2366 6.63 0.0127 0.36 February
3/27/2017 ST4 969 0.7292 22.60 0.0364 1.13 March
4/27/2017 ST4 2911 1.9522 58.57 0.1272 3.82 April
5/23/2017 ST4 ND ND ND ND ND May
6/12/2017 ST4 1584 1.6539 49.62 0.0930 2.79 June
7/5/2017 ST4 171 0.1499 4.65 0.0060 0.19 July
8/15/2017 ST4 3743 3.2070 99.42 0.0981 3.04 August
9/11/2017 ST4 685 0.7796 23.39 0.0422 1.27 September
10/24/2017 ST4 580 0.6899 21.39 0.0963 2.99 October
2/8/2017 ST4A 70 0.0627 1.75 0.0006 0.02 February
3/27/2017 ST4A 159 0.0915 2.84 0.0005 0.02 March
9/11/2017 ST4A 710 1.0488 31.46 0.0279 0.84 September
2/8/2017 ST6B 159 0.1037 2.90 0.0035 0.10 February
3/27/2017 ST6B 489 0.2556 7.92 0.0087 0.27 March
4/27/2017 ST6B 856 0.5221 15.66 0.0243 0.73 April
5/23/2017 ST6B 1737 3.4664 107.46 0.0551 1.71 May
6/12/2017 ST6B 208 0.4185 12.56 0.0086 0.26 June
7/5/2017 ST6B 1798 2.0030 62.09 0.1830 5.67 July
8/15/2017 ST6B 0 0.0000 0.00 0.0000 0.00 August
9/11/2017 ST6B 1676 1.4075 42.22 0.0645 1.94 September
10/24/2017 ST6B 1121 1.2595 39.05 0.3695 11.45 October
5/23/2017 WPH OUTLET 5811 5.1762 160.46 0.2565 7.95 May
6/12/2017 WPH OUTLET 1182 1.3769 41.31 0.0625 1.88 June
8/15/2017 WPH OUTLET 976 0.7176 22.25 0.0248 0.77 August
9/11/2017 WPH OUTLET 1994 2.2316 66.95 0.1279 3.84 September
10/24/2017 WPH OUTLET 612 0.6896 21.38 0.0947 2.94 October
48
Table H. 2016 flows and nitrogen and phosphorus loads determined for two streams at
sampling stations 4 and 6B. Station 4A is upgradient of station 4 in the same stream.
Table I. 2015 flows and nitrogen loads determined for three streams. Stations 4 and
6B were also sampled in 2016.
Measured TN Load TN Load TP Load TP Load Representative
Sample ID Date Flow Month
(m3/d)(kg/day)(kg/month)(kg/day)(kg/month)
STA4 3/16/2016 6044 3.455 107.11 0.457 14.15 March
STA4 4/20/2016 2544 1.464 43.92 0.228 6.85 April
STA4 5/17/2016 1479 1.139 35.32 0.124 3.86 May
STA4 6/14/2016 451 0.425 12.74 0.056 1.69 June
STA4 7/21/2016 0 0.000 0.00 0.000 0.00 July
STA4A 3/16/2016 734 0.405 12.55 0.009 0.29 March
STA4A 4/20/2016 361 0.199 5.96 0.004 0.12 April
STA4A 5/17/2016 183 0.115 3.56 0.003 0.08 May
STA4A 6/14/2016 214 0.163 4.90 0.004 0.12 June
STA4A 7/21/2016 31 0.029 0.90 0.001 0.03 July
STA6B 3/16/2016 452 0.215 6.67 0.013 0.40 March
STA6B 4/20/2016 449 0.176 5.27 0.013 0.38 April
STA6B 5/17/2016 1154 0.644 19.98 0.038 1.17 May
STA6B 6/14/2016 2418 3.045 91.36 0.645 19.34 June
STA6B 7/21/2016 75 0.071 2.21 0.027 0.84 July
Measured TN Load TN Load Representative
Sample ID Date Flow Month
(m3/d)(kg/day)(kg/month)
ST3 6/8/2015 259 0.301 9.0 June
ST3 7/6/2015 189 0.294 9.1 July
ST3 8/3/2015 83 0.078 2.4 August
ST3 8/31/2015 21 0.010 0.3 September
ST4 6/8/2015 2157 2.135 64.1 June
ST4 7/6/2015 999 0.981 30.4 July
ST4 8/3/2015 0 0.000 0.0 August
ST4 8/31/2015 104 0.107 3.2 September
ST6B 6/8/2015 457 0.385 11.5 June
ST6B 7/6/2015 444 0.799 24.8 July
ST6B 8/3/2015 92 0.074 2.3 August
ST6B 8/31/2015 88 0.083 2.5 September
49
The effect of stream inputs requires further analysis, because while flows and loads
from stream sites ST4 and 6B were measurably higher in 2017 compared to 2016 and
2015, TN concentrations at stations Nan-5 and Nan-6 in Polpis Harbor were not
significantly different from concentrations measured in 2016. Additionally, TN levels
were lower in 2016 compared to 2015. Moreover, in regard to stream sampling location
ST4 and ST4A (up-gradient of ST4 but selected by the Conservation Foundation to
represent water before influence of the bogs), for the months of February and March in
2017 where there was data for both stations, TN load at ST4A compared to ST4 ranged
from 12% to 25% (2016 TN load at ST4A compared to ST4 ranged from 12% to 38% of
the measured load at ST4) indicating substantial “pick-up” of groundwater occurs
between these stations. Equally important, in 2017 TN load for the period June through
October from ST4 accounted for 27% more load when compared to load leaving ST6B
(June-October load at ST4 = 198 kg vs. ST6B = 156 kg). Additionally, load from WPH
OUTLET which enters west Polpis Harbor along with loads from ST6B is an equally
significant input to that portion of the Polpis Harbor system (June-October load at WPH
OUTLET = 152 kg vs. ST6B = 156 kg). The WPH OUTLET load maybe greater than
that measured at STA6B simply because there was no data for July from the WPH
OUTLET location. As previously mentioned in 2016, it would be important to more
accurately quantify flows and loads from WPH OUTLET, ST4 and the up-gradient bog
system as this surfacewater source may be the main driver of TN levels at Nan-5 and 6
in Polpis Harbor. Given these complexities, a detailed investigation of flow and loads
throughout the network of bogs up-gradient of ST4 and WPH OUTLET is warranted to
refine management of nutrients entering Polpis Harbor from its associated sub-
watershed. Further study would be helpful to determine whether the cranberry bogs will
benefit from best management practices to limit their influence in contributing nitrogen
to Polpis Harbor. As such, it may be preferable that such an investigation be completed
by the bog owner: The Nantucket Conservation Foundation in collaboration with the bog
manager who would have detailed information on bog operating practices critical to
ensure sample timing and bog management practices are coordinated.
Additional estuarine stations (ORS-2,3,4,5,6) were added in 2015 to the sampling
stations in Nantucket Harbor and Madaket Harbor (ORS-1) specifically to monitor water
quality in the vicinity of potential sites for deployment of oyster aquaculture. A subset of
the 2015 stations (ORS-2,4,6) were sampled again in 2016 and 2017. These stations
had never been sampled prior to 2015 so it is not possible to compare 2017, 2016 and
2015 results to past years, however, 2017, 2016 and 2015 results for stations ORS-
2,4,6 can serve as the beginning of establishing a baseline for gauging changes in
future years. 2017 TN levels at ORS-2,4,6 (0.329 mg/L, 0.414 mg/L, 0.460 mg/L) were
very similar to 2016 levels (0.339 mg/L, 0.382 mg/L, 0.472 mg/L) and lower then in 2015
at ORS-2,4,6 (0.338 mg/L, 0.415 mg/L, 0.551 mg/L). Station concentrations are
generally consistent with the water quality from nearby long term monitoring stations. In
the future a detailed interpretation of the data collected at these stations will be possible
once more data becomes available.
50
Table 2a. Summary of Stream Water Quality Parameters (ST4, ST6, WPH OUTLET) and stations associated with potential oyster
aquaculture locations (ORS,2,4,6), 2018 Nantucket Sampling Program. STA4A was added in 2016 to further interpret flow and load
results from STA4, however, in 2017 there were dates when there was no flow at STA4A and in 2018 samples were not collected from
STA4A.
Lab Avg.Avg.Avg.Avg.Avg.Avg.Avg.Avg.Avg.Avg.Avg.Avg.Avg.Avg.
Date Location Sample ID Salinity PO4 TP NH4 Nox DIN DON TDN POC PON TON TN Chla Phaeo Total Pig
ppt (mg/L)(mg/L)(mg/L)(mg/L)(mg/L)(mg/L)(mg/L)(mg/L)(mg/L)(mg/L)(mg/L)(ug/L)(ug/L)(ug/L)
4/25/2018 NANTUCKET STREAMS ST4 0.10 0.028 0.042 0.004 0.003 0.007 0.305 0.268 0.335 0.019 0.325 0.332 NS NS NS
6/6/2018 NANTUCKET STREAMS ST4 0.10 0.032 0.056 0.016 0.008 0.024 0.545 0.488 0.467 0.028 0.573 0.597 NS NS NS
6/26/2018 NANTUCKET STREAMS ST4 0.10 0.037 0.067 0.008 0.013 0.021 0.548 0.488 0.358 0.030 0.578 0.599 0.93 1.52 2.45
7/24/2018 NANTUCKET STREAMS ST4 0.10 0.023 0.678 0.004 0.006 0.010 0.475 0.416 1.305 0.102 0.577 0.587 4.80 1.05 5.85
8/21/2018 NANTUCKET STREAMS ST4 0.10 0.026 0.376 0.007 0.016 0.023 0.608 0.541 15.878 0.986 1.593 1.617 7.13 5.19 12.32
4/25/2018 NANTUCKET STREAMS ST6 0.00 0.023 0.032 0.008 0.011 0.019 0.281 0.257 0.501 0.024 0.305 0.324 NS NS NS
6/6/2018 NANTUCKET STREAMS ST6 1.00 0.026 0.060 0.015 0.006 0.022 0.471 0.423 1.034 0.041 0.512 0.534 NS NS NS
6/26/2018 NANTUCKET STREAMS ST6 0.00 0.070 0.112 0.014 0.000 0.014 0.522 0.459 1.665 0.095 0.617 0.630 0.52 1.82 2.34
7/24/2018 NANTUCKET STREAMS ST6 0.00 0.091 0.261 0.015 0.006 0.021 0.367 0.333 6.480 0.370 0.736 0.758 0.32 0.43 0.75
8/21/2018 NANTUCKET STREAMS ST6 0.10 0.015 0.244 0.005 0.002 0.007 0.184 0.163 5.825 0.250 0.434 0.441 0.07 1.40 1.47
4/25/2018 NANTUCKET STREAMS WPH OUTLET 0.50 0.026 0.279 0.021 0.004 0.026 0.288 0.269 0.451 0.031 0.319 0.344 NS NS NS
6/6/2018 NANTUCKET STREAMS WPH OUTLET 0.10 0.034 0.063 0.015 0.007 0.022 0.522 0.466 0.542 0.033 0.555 0.577 NS NS NS
6/26/2018 NANTUCKET STREAMS WPH OUTLET 0.10 0.039 0.065 0.011 0.009 0.020 0.528 0.470 0.432 0.034 0.562 0.582 0.86 1.48 2.34
8/21/2018 NANTUCKET STREAMS WPH OUTLET NS 0.025 0.149 0.067 0.015 0.082 0.243 0.278 2.108 0.317 0.560 0.641 31.42 17.03 48.45
Lab Avg.Avg.Avg.Avg.Avg.Avg.Avg.Avg.Avg.Avg.Avg.Avg.Avg.Avg.
Date Location Salinity PO4 TP NH4 Nox DIN DON TDN POC PON TON TN Chla Phaeo Total Pig
Sample ID ppt (mg/L)(mg/L)(mg/L)(mg/L)(mg/L)(mg/L)(mg/L)(mg/L)(mg/L)(mg/L)(mg/L)(ug/L)(ug/L)(ug/L)
6/5/2018 Old North Wharf - Oyster ORS2 31.30 0.009 NS 0.020 0.0004 0.020 0.140 0.160 0.650 0.095 0.235 0.255 2.79 1.78 4.56
7/5/2018 Old North Wharf - Oyster ORS2 29.60 0.018 NS 0.012 0.0004 0.013 0.145 0.157 0.692 0.106 0.251 0.264 2.65 0.89 3.54
8/1/2018 Old North Wharf - Oyster ORS2 31.40 0.020 NS 0.003 0.0004 0.003 0.175 0.179 0.464 0.082 0.257 0.261 3.44 0.03 3.47
9/12/2018 Old North Wharf - Oyster ORS2 31.20 0.031 NS 0.012 0.0004 0.013 0.144 0.157 0.326 0.054 0.198 0.211 1.77 0.56 2.33
6/5/2018 Shimmo - Oyster ORS4 29.70 0.007 NS 0.000 0.0004 0.001 0.109 0.110 0.625 0.101 0.210 0.211 2.90 2.20 5.10
8/1/2018 Shimmo - Oyster ORS4 30.90 0.023 NS 0.007 0.0004 0.007 0.179 0.186 0.632 0.126 0.305 0.312 1.88 0.29 2.17
9/12/2018 Shimmo - Oyster ORS4 30.60 0.028 NS 0.028 0.0004 0.028 0.204 0.233 0.497 0.090 0.294 0.322 2.65 1.04 3.69
7/5/2018 Shimmo - Oyster ORS4 29.00 0.023 NS 0.018 0.0037 0.022 0.162 0.184 0.747 0.132 0.294 0.316 4.92 1.28 6.19
6/5/2018 Polpis - Oyster ORS6 30.50 0.012 NS 0.008 0.0004 0.008 0.163 0.171 0.780 0.124 0.287 0.295 2.67 2.21 4.89
7/5/2018 Polpis - Oyster ORS6 28.80 0.030 NS 0.012 0.0004 0.013 0.130 0.142 1.366 0.215 0.345 0.358 6.96 1.71 8.66
8/1/2018 Polpis - Oyster ORS6 30.70 0.027 NS 0.010 0.0004 0.010 0.191 0.201 0.792 0.167 0.358 0.369 3.60 1.39 4.99
9/12/2018 Polpis - Oyster ORS6 31.30 0.030 NS 0.006 0.0004 0.007 0.223 0.230 4.674 0.544 0.767 0.774 28.10 0.03 28.12
51
Table 2b. Summary of Stream Water Quality Parameters (ST4,ST4A,ST6B) and stations associated with potential oyster aquaculture
locations (ORS,2,4,6), 2017 Nantucket Sampling Program. STA4A was added in 2016 to further interpret flow and load results from
STA4, however, in 2017 there were dates when there was no flow at STA4A.
Lab Avg.Avg.Avg.Avg.Avg.Avg.Avg.Avg.Avg.Avg.Avg.Avg.Avg.Avg.
Date Location Sample ID Salinity PO4 TP NH4 Nox DIN DON TDN POC PON TON TN Chla Phaeo Total Pig
ppt (mg/L)(mg/L)(mg/L)(mg/L)(mg/L)(mg/L)(mg/L)(mg/L)(mg/L)(mg/L)(mg/L)(ug/L)(ug/L)(ug/L)
2/8/2017 NANTUCKET STREAMS ST4 0.10 0.037 0.051 0.007 0.005 0.012 0.629 0.549 0.777 0.050 0.679 0.691 1.35 0.93 2.280
3/27/2017 NANTUCKET STREAMS ST4 0.10 0.038 0.055 0.012 0.009 0.020 0.703 0.620 0.364 0.029 0.732 0.753 1.01 0.14 1.153
4/27/2017 NANTUCKET STREAMS ST4 0.10 0.044 0.064 0.011 0.005 0.016 0.631 0.555 0.282 0.023 0.655 0.671 0.53 0.79 1.325
5/23/2017 NANTUCKET STREAMS ST4 0.10 0.036 0.063 0.007 0.014 0.020 0.967 0.846 0.808 0.046 1.013 1.033 0.77 1.31 2.087
6/12/2017 NANTUCKET STREAMS ST4 0.10 0.059 0.086 0.016 0.014 0.029 0.958 0.846 0.736 0.057 1.015 1.044 1.19 0.99 2.184
7/5/2017 NANTUCKET STREAMS ST4 0.10 0.035 NS 0.011 0.004 0.015 0.806 0.704 0.629 0.039 0.845 0.875 0.63 0.89 1.522
8/15/2017 NANTUCKET STREAMS ST4 0.10 0.026 0.053 0.007 0.002 0.010 0.742 0.644 1.649 0.095 0.837 0.857 3.05 0.03 3.073
9/11/2017 NANTUCKET STREAMS ST4 0.10 0.062 0.085 0.021 0.002 0.023 1.079 0.945 0.569 0.036 1.115 1.138 1.53 0.46 1.987
10/24/2017 NANTUCKET STREAMS ST4 0.10 0.166 0.227 0.007 0.006 0.013 1.142 0.990 0.505 0.035 1.177 1.190 0.02 0.36 0.374
2/8/2017 NANTUCKET STREAMS ST4A 0.10 0.009 0.018 0.011 0.009 0.020 0.851 0.747 0.450 0.028 0.879 0.899 0.09 2.68 2.767
3/27/2017 NANTUCKET STREAMS ST4A 0.10 0.003 0.012 0.011 0.008 0.019 0.514 0.457 0.451 0.043 0.556 0.575 0.24 0.33 0.566
9/11/2017 NANTUCKET STREAMS ST4A 0.10 0.039 0.079 0.025 0.009 0.034 1.387 1.219 0.533 0.056 1.444 1.478 0.10 0.85 0.949
2/8/2017 NANTUCKET STREAMS ST6B 0.10 0.022 0.030 0.010 0.007 0.017 0.603 0.531 0.557 0.032 0.635 0.652 0.39 0.55 0.942
3/27/2017 NANTUCKET STREAMS ST6B 0.10 0.018 0.027 0.019 0.037 0.055 0.444 0.428 0.400 0.023 0.467 0.522 0.26 0.20 0.458
4/27/2017 NANTUCKET STREAMS ST6B 0.00 0.028 0.040 0.013 0.008 0.021 0.553 0.492 0.664 0.036 0.589 0.610 0.50 0.82 1.316
5/23/2017 NANTUCKET STREAMS ST6B 0.00 0.032 0.057 0.013 0.015 0.028 1.930 1.679 0.672 0.037 1.967 1.996 0.55 1.35 1.894
6/12/2017 NANTUCKET STREAMS ST6B 0.00 0.041 0.062 0.016 0.015 0.031 1.927 1.679 1.124 0.054 1.981 2.013 0.65 0.95 1.600
7/5/2017 NANTUCKET STREAMS ST6B 0.00 0.102 NS 0.003 0.005 0.008 0.581 0.505 13.568 0.516 1.097 1.114 0.63 2.03 2.667
8/15/2017 NANTUCKET STREAMS ST6B 0.10 0.025 0.068 0.007 0.003 0.010 0.355 0.313 1.457 0.067 0.422 0.442 14.21 0.03 14.232
9/11/2017 NANTUCKET STREAMS ST6B 0.00 0.039 0.054 0.016 0.003 0.019 0.787 0.691 0.640 0.033 0.821 0.840 0.04 0.38 0.416
10/24/2017 NANTUCKET STREAMS ST6B 0.00 0.330 0.525 0.019 0.004 0.023 1.063 0.931 1.009 0.038 1.101 1.124 0.00 0.90 0.901
5/23/2017 NANTUCKET STREAMS WPH OUTLET 1.00 0.044 0.074 0.006 0.007 0.013 0.823 0.716 0.902 0.055 0.878 0.891 0.30 1.29 1.590
6/12/2017 NANTUCKET STREAMS WPH OUTLET 2.00 0.053 0.102 0.018 0.013 0.031 1.074 0.947 0.908 0.060 1.134 1.165 1.99 0.99 2.975
8/15/2017 NANTUCKET STREAMS WPH OUTLET 0.70 0.025 0.047 0.019 0.004 0.023 0.627 0.557 1.079 0.062 0.689 0.735 0.60 0.03 0.623
9/11/2017 NANTUCKET STREAMS WPH OUTLET 0.10 0.064 0.087 0.020 0.006 0.026 1.052 0.924 0.707 0.041 1.093 1.119 0.20 0.75 0.958
10/24/2017 NANTUCKET STREAMS WPH OUTLET 0.10 0.155 0.216 0.011 0.008 0.019 1.063 0.927 0.793 0.046 1.109 1.127 0.06 0.70 0.762
52
Table 2b cont'd. Summary of Stream Water Quality Parameters (ST4,ST4A,ST6B) and stations associated with potential oyster
aquaculture locations (ORS,2,4,6), 2017 Nantucket Sampling Program. STA4A was added in 2016 to further interpret flow and load
results from STA4, however, in 2017 there were dates when there was no flow at STA4A.
Lab Avg.Avg.Avg.Avg.Avg.Avg.Avg.Avg.Avg.Avg.Avg.Avg.Avg.Avg.
Date Location Salinity PO4 TP NH4 Nox DIN DON TDN POC PON TON TN Chla Phaeo Total Pig
Sample ID ppt (mg/L)(mg/L)(mg/L)(mg/L)(mg/L)(mg/L)(mg/L)(mg/L)(mg/L)(mg/L)(mg/L)(ug/L)(ug/L)(ug/L)
5/17/2017 Old North Wharf - Oyster ORS2 31.90 0.009 NS 0.016 0.003 0.019 0.213 0.231 0.450 0.083 0.296 0.314 2.08 0.87 2.95
6/14/2017 Old North Wharf - Oyster ORS2 30.30 0.004 NS 0.013 0.001 0.014 0.220 0.234 0.283 0.049 0.269 0.283 3.98 0.75 4.73
7/12/2017 Old North Wharf - Oyster ORS2 NS 0.023 NS 0.035 0.003 0.038 0.206 0.244 NS NS NS NS NS NS NS
8/10/2017 Old North Wharf - Oyster ORS2 31.00 0.014 NS 0.014 0.001 0.015 0.262 0.277 0.296 0.043 0.305 0.334 1.87 0.03 1.89
9/25/2017 Old North Wharf - Oyster ORS2 29.70 0.021 NS 0.063 0.013 0.076 0.242 0.318 0.302 0.052 0.294 0.370 1.59 0.81 2.40
5/17/2017 Shimmo - Oyster ORS4 30.70 0.009 NS 0.014 0.012 0.027 0.387 0.414 0.296 0.049 0.436 0.463 1.02 0.87 1.89
6/14/2017 Shimmo - Oyster ORS4 29.70 0.012 NS 0.022 0.007 0.029 0.284 0.313 0.318 0.059 0.343 0.372 1.55 1.19 2.74
7/12/2017 Shimmo - Oyster ORS4 30.10 0.019 NS 0.035 0.003 0.038 0.257 0.295 0.326 0.054 0.311 0.386 1.57 1.50 3.07
8/10/2017 Shimmo - Oyster ORS4 30.30 0.017 NS 0.014 0.003 0.017 0.462 0.479 0.306 0.051 0.514 0.548 1.02 0.35 1.37
9/25/2017 Shimmo - Oyster ORS4 29.10 0.027 NS 0.047 0.027 0.074 0.225 0.299 0.310 0.050 0.276 0.350 1.30 0.76 2.06
5/17/2017 Polpis - Oyster ORS6 30.20 0.009 NS 0.011 0.000 0.011 0.230 0.241 0.417 0.074 0.304 0.315 1.56 0.86 2.43
6/14/2017 Polpis - Oyster ORS6 30.00 0.009 NS 0.010 0.001 0.011 0.322 0.333 0.306 0.054 0.376 0.387 1.68 1.07 2.75
7/12/2017 Polpis - Oyster ORS6 30.20 0.021 NS 0.046 0.006 0.052 0.393 0.445 0.542 0.101 0.494 0.598 3.33 0.90 4.23
8/10/2017 Polpis - Oyster ORS6 30.10 0.020 NS 0.026 0.002 0.028 0.307 0.335 0.344 0.061 0.368 0.424 0.38 0.34 0.73
9/25/2017 Polpis - Oyster ORS6 28.70 0.027 NS 0.069 0.011 0.080 0.271 0.351 0.529 0.079 0.350 0.430 1.82 1.52 3.35
53
Table 2c. Summary of Stream Water Quality Parameters (ST4,ST4A,ST6B) and stations associated with potential oyster aquaculture
locations (ORS,2,4,6), 2016 Nantucket Sampling Program. Station STA3 from 2015 was discontinued due to zero flow (should be
checked in out years to confirm flow) and STA4A was added to further interpret flow and load results from STA4.
Lab Avg.Avg.Avg.Avg.Avg.Avg.Avg.Avg.Avg.Avg.Avg.Avg.Avg.Avg.
Salinity PO4 TP NH4 Nox DIN DON TDN POC PON TON TN Chla Phaeo Total Pig
Date Embayment Sample ID ppt (mg/L)(mg/L)(mg/L)(mg/L)(mg/L)(mg/L)(mg/L)(mg/L)(mg/L)(mg/L)(mg/L)(ug/L)(ug/L)(ug/L)
3/16/2016 Stream to Polpis STA4 0.1 0.044 0.076 0.012 0.001 0.014 0.529 0.543 0.323 0.029 0.558 0.572 0.42 0.45 0.87
4/20/2016 Stream to Polpis STA4 0.1 0.045 0.090 0.008 0.001 0.009 0.538 0.547 0.299 0.028 0.566 0.575 0.49 0.54 1.03
5/17/2016 Stream to Polpis STA4 0.2 0.071 0.084 0.014 0.001 0.015 0.715 0.730 0.464 0.041 0.756 0.770 0.44 0.70 1.15
6/14/2016 Stream to Polpis STA4 0.1 0.064 0.125 0.022 0.004 0.026 0.862 0.888 0.552 0.054 0.915 0.942 0.40 1.15 1.55
7/21/2016 NS STA4 NS NS NS NS NS NS NS NS NS NS NS NS NS NS NS
3/16/2016 Stream to Polpis STA4A 0.1 0.007 0.013 0.012 0.001 0.013 0.515 0.528 0.259 0.023 0.539 0.552 0.11 0.45 0.55
4/20/2016 Stream to Polpis STA4A 0.1 0.005 0.012 0.010 0.002 0.012 0.512 0.524 0.295 0.027 0.539 0.551 0.28 0.46 0.74
5/17/2016 Stream to Polpis STA4A 0.1 0.006 0.014 0.014 0.000 0.014 0.584 0.597 0.523 0.031 0.615 0.628 3.89 2.26 6.15
6/14/2016 Stream to Polpis STA4A 0.0 0.010 0.019 0.022 0.006 0.028 0.704 0.733 0.310 0.030 0.734 0.763 1.10 1.85 2.94
7/21/2016 Stream to Polpis STA4A 0.1 0.016 0.027 0.023 0.010 0.032 0.856 0.888 0.441 0.050 0.906 0.938 0.20 0.92 1.13
3/16/2016 Stream to Polpis STA6B 0.0 0.021 0.028 0.013 0.003 0.016 0.434 0.450 0.309 0.026 0.460 0.476 0.15 0.40 0.55
4/20/2016 Stream to Polpis STA6B 0.0 0.018 0.028 0.010 0.002 0.012 0.361 0.373 0.257 0.019 0.379 0.392 0.39 0.57 0.96
5/17/2016 Stream to Polpis STA6B 0.0 0.025 0.033 0.014 0.002 0.015 0.516 0.531 0.351 0.028 0.543 0.558 0.38 0.69 1.07
6/14/2016 Stream to Polpis STA6B 0.0 0.118 0.267 0.023 0.008 0.031 0.891 0.922 7.398 0.338 1.229 1.259 0.35 2.01 2.36
7/21/2016 Stream to Polpis STA6B 0.0 0.173 0.361 0.020 0.008 0.028 0.604 0.632 7.724 0.317 0.921 0.949 0.005 0.39 0.40
Lab Avg.Avg.Avg.Avg.Avg.Avg.Avg.Avg.Avg.Avg.Avg.Avg.Avg.Avg.
Salinity PO4 TP NH4 Nox DIN DON TDN POC PON TON TN Chla Phaeo Total Pig
Date Embayment Sample ID ppt (mg/L)(mg/L)(mg/L)(mg/L)(mg/L)(mg/L)(mg/L)(mg/L)(mg/L)(mg/L)(mg/L)(ug/L)(ug/L)(ug/L)
5/12/2016 Old North Wharf - Oyster ORS2 31.5 0.006 NS 0.004 0.000 0.004 0.144 0.148 0.222 0.036 0.180 0.184 0.61 0.38 0.99
6/27/2016 Old North Wharf - Oyster ORS2 32.0 0.014 NS 0.008 0.009 0.017 0.195 0.213 0.430 0.074 0.269 0.287 1.57 0.73 2.30
7/11/2016 Old North Wharf - Oyster OR2 31.1 0.018 NS 0.007 0.003 0.010 0.248 0.258 0.589 0.104 0.352 0.362 3.66 0.66 4.32
8/25/2016 Old North Wharf - Oyster ORS2 32.1 0.014 NS 0.004 0.002 0.006 0.098 0.104 0.478 0.081 0.178 0.184 1.43 0.55 1.98
9/20/2016 Old North Wharf - Oyster ORS2 32.0 0.021 NS 0.006 0.007 0.013 0.425 0.438 0.331 0.087 0.512 0.525 0.59 0.60 1.19
5/12/2016 Shimmo - Oyster ORS4 30.8 0.008 NS 0.004 0.008 0.012 0.147 0.159 0.252 0.038 0.185 0.197 0.48 0.32 0.80
6/27/2016 Shimmo - Oyster ORS4 31.6 0.016 NS 0.012 0.001 0.013 0.202 0.214 0.836 0.162 0.364 0.377 3.83 0.82 4.65
7/11/2016 Shimmo - Oyster OR4 29.7 0.022 NS 0.012 0.006 0.018 0.289 0.307 0.647 0.117 0.406 0.424 1.35 1.16 2.51
8/25/2016 Shimmo - Oyster ORS4 31.5 0.019 NS 0.008 0.003 0.010 0.128 0.138 0.727 0.125 0.253 0.263 1.50 1.41 2.91
8/25/2016 Shimmo - Oyster ORS4 31.4 0.019 NS 0.012 0.002 0.014 0.139 0.153 0.656 0.112 0.251 0.265 1.14 1.25 2.40
9/20/2016 Shimmo - Oyster ORS4 31.4 0.019 NS 0.007 0.006 0.013 0.287 0.300 0.840 0.165 0.452 0.465 3.13 0.52 3.64
5/12/2016 Polpis - Oyster ORS6 30.5 0.008 NS 0.005 0.000 0.005 0.157 0.162 0.337 0.050 0.207 0.212 0.59 0.64 1.23
6/27/2016 Polpis - Oyster ORS6 32.0 0.024 NS 0.008 0.001 0.009 0.280 0.289 0.566 0.101 0.381 0.390 1.80 1.05 2.86
7/11/2016 Polpis - Oyster OR6 30.9 0.021 NS 0.061 0.002 0.063 0.298 0.360 0.769 0.137 0.435 0.498 2.96 1.43 4.39
8/25/2016 Polpis - Oyster ORS6 32.1 0.027 NS 0.018 0.002 0.020 0.173 0.194 ----0.844 --4.49 4.61 9.09
9/20/2016 Polpis - Oyster ORS6 31.4 0.026 NS 0.006 0.006 0.011 0.334 0.345 1.947 0.185 0.519 0.530 3.01 0.36 3.37
54
Table 2d. Summary of Stream Water Quality Parameters (ST3,ST4,ST6B) and stations associated with potential oyster aquaculture
locations (ORS1,2,3,4,5,6), 2015 Nantucket Sampling Program.
Avg.Avg.Avg.Avg.Avg.Avg.Avg.Avg.Avg.Avg.Avg.Avg.Avg.
Sample ID Date Embayment PO4 NH4 Nox DIN DON TDN POC PON TON TN Chla Phaeo Total Pig
(mg/L)(mg/L)(mg/L)(mg/L)(mg/L)(mg/L)(mg/L)(mg/L)(mg/L)(mg/L)(ug/L)(ug/L)(ug/L)
ST3 6/8/2015 ND 0.011 0.012 0.056 0.068 0.369 0.437 9.117 0.724 1.093 1.160 2.334 4.934 7.267
ST3 7/6/2015 STREAMS TO POLPIS 0.012 0.007 0.052 0.059 0.369 0.429 19.465 1.126 1.495 1.554 0.884 2.088 2.971
ST3 8/3/2015 STREAMS TO POLPIS 0.021 0.004 0.049 0.052 0.330 0.382 10.349 0.557 0.886 0.939 0.025 0.757 0.782
ST3 8/31/2015 STREAMS TO POLPIS 0.010 0.010 0.050 0.059 0.229 0.289 4.055 0.211 0.440 0.499 0.476 5.067 5.543
ST4 6/8/2015 ND 0.037 0.010 0.001 0.011 0.942 0.953 0.539 0.037 0.979 0.990 0.612 1.536 2.148
ST4 7/6/2015 STREAMS TO POLPIS 0.044 0.010 0.000 0.010 0.935 0.945 0.454 0.037 0.972 0.982 0.261 0.652 0.913
ST4 8/3/2015 STREAMS TO POLPIS 0.168 0.026 0.002 0.028 0.975 1.003 4.852 0.243 1.218 1.246 0.109 0.482 0.591
ST4 8/31/2015 STREAMS TO POLPIS 0.077 0.020 0.001 0.021 0.905 0.926 1.596 0.098 1.003 1.024 1.104 1.266 2.370
ST6B 6/8/2015 STREAMS TO POLPIS 0.024 0.011 0.000 0.011 0.649 0.660 3.694 0.182 0.831 0.842 1.310 2.059 3.369
ST6B 7/6/2015 STREAMS TO POLPIS 0.166 0.007 0.001 0.007 0.790 0.797 22.908 1.003 1.793 1.801 0.329 0.745 1.074
ST6B 8/3/2015 STREAMS TO POLPIS 0.012 0.014 0.001 0.015 0.322 0.337 11.321 0.469 0.791 0.806 0.200 0.519 0.719
ST6B 8/31/2015 STREAMS TO POLPIS 0.026 0.077 0.014 0.091 0.411 0.502 9.627 0.443 0.854 0.945 3.178 7.018 10.196
Avg.Avg.Avg.Avg.Avg.Avg.Avg.Avg.Avg.Avg.Avg.Avg.Avg.
Sample ID Date Embayment PO4 NH4 Nox DIN DON TDN POC PON TON TN Chla Phaeo Total Pig
(mg/L)(mg/L)(mg/L)(mg/L)(mg/L)(mg/L)(mg/L)(mg/L)(mg/L)(mg/L)(ug/L)(ug/L)(ug/L)
ORS1 6/9/2015 MADAKET 0.037 0.015 0.005 0.020 0.287 0.307 0.849 0.119 0.406 0.426 3.376 4.160 7.536
ORS1 7/6/2015 MADAKET HITHER CREEK 0.025 0.000 0.014 0.014 0.373 0.388 1.072 0.231 0.604 0.618 6.118 4.891 11.009
ORS2 6/9/2015 OLD NORTH WHARF 0.014 0.019 0.000 0.019 0.200 0.219 0.563 0.090 0.290 0.309 2.855 2.202 5.057
ORS2 7/6/2015 OLD NORTH WHARF 0.016 0.004 0.007 0.011 0.287 0.298 0.532 0.086 0.373 0.384 1.733 1.453 3.186
ORS2 8/3/2015 OLD NORTH WHARF 0.019 0.017 0.011 0.028 0.254 0.282 0.350 0.059 0.313 0.341 0.661 1.806 2.467
ORS2 9/2/2014 OLD NORTH WHARF 0.026 0.020 0.001 0.021 0.225 0.246 0.407 0.072 0.297 0.318 1.523 1.940 3.463
ORS3 6/9/2015 MONOMOY CREEKS 0.024 0.014 0.036 0.050 0.294 0.344 0.473 0.077 0.371 0.421 1.563 2.419 3.983
ORS3 7/6/2015 MONOMOY CREEKS 0.028 0.029 0.047 0.076 0.429 0.504 0.522 0.082 0.511 0.587 1.212 1.491 2.703
ORS4 8/3/2015 PIMENYS POINT 0.012 0.015 0.002 0.016 0.369 0.385 0.373 0.064 0.433 0.449 0.909 1.193 2.102
ORS4 9/2/2014 SHIMMO 0.026 0.056 0.003 0.059 0.214 0.273 0.596 0.109 0.323 0.382 2.712 2.476 5.188
ORS5 8/3/2015 DUCKS HOLM 0.009 0.012 0.003 0.015 0.460 0.475 0.351 0.063 0.522 0.537 0.904 0.849 1.753
ORS5 9/2/2014 DUCKS HOLM 0.014 0.013 0.000 0.013 0.302 0.315 0.493 0.089 0.391 0.404 1.237 2.264 3.501
ORS6 8/3/2015 POLPIS 0.020 0.013 0.000 0.013 0.533 0.546 0.683 0.112 0.645 0.658 1.589 2.614 4.204
ORS6 9/2/2014 POLPIS 0.035 0.050 0.000 0.050 0.299 0.349 0.561 0.094 0.393 0.443 1.451 2.696 4.147
55
Trophic State of the Estuaries of Nantucket Island
The Trophic State of an estuary is a quantitative indicator of its nutrient related
ecological health and is based on key ecological metrics: concentrations of inorganic
and organic Nitrogen, water clarity (Secchi Depth), lowest measured concentrations of
Dissolved Oxygen (average of lowest 20% of measurements), and Chlorophyll-a
pigments (surrogate for phytoplankton biomass/blooms). Nutrient related trophic health
scales generally range from Oligotrophic (healthy-low nutrient) to Mesotrophic (showing
some signs of deterioration of health due to nutrient enrichment) to Eutrophic (habitats
significantly impaired and degraded, high levels of nutrients and organic matter and
community shifts). The Trophic Health Index Score used here is a standard numerical
scale based on criteria for open water embayments and uses the above mentioned
measured parameters to create a habitat quality scale (Howes et al. 1999,
http://www.savebuzzardsbay.org). For the estuaries within the Town of Nantucket, a
trophic index score was calculated for each sampling location for each year (2010 and
2012- 2018) using the summer monitoring results. The Index scores were calculated
in 2 ways, one which included the low dissolved oxygen for each year in the index ("with
DO", Table 8) and one which excluded the oxygen metric ("without DO", Table 9). The
reason for this dual approach is that in some estuaries, such as those on Nantucket,
there are only periodic depletions in bottom water dissolved oxygen, generally related to
meteorological events acting on nutrient enriched basins. While these short-term
depletions have important ecological consequences, they are difficult to capture in
programs that sample 4 or 5 dates per summer. In these cases, inclusion of the oxygen
can bias the Index upwards (i.e. higher quality) because of the greater probability of
capturing high versus low oxygen events (i.e. missing periodic low oxygen events). This
bias was found in the previous analysis of the 2010 dataset, as well as for other
estuaries in s.e. Massachusetts. However, this is not always the case and there was no
substantive “biasing high” between the "with DO" and "without DO" Index scores based
on the 2013 and 2014 data and again in 2016 and 2017 none-the-less, the index
analysis by both methods is presented for informational purposes herein (Tables 8a-g
and 9a-g). It should be noted that to the extent the bias does exist in a given year, it
relates only to the oxygen data, the other water quality parameters do not change as
rapidly as dissolved oxygen and therefore the sampling program adequately captures
accurate concentrations of nutrient related metrics (DO changes by the hour). Further
analysis of the with DO and without DO index values for all stations and monitoring
years indicates that there is very little difference in the determined index value between
the methods (RPD <10%; generally <5%). The exception was in Miacomet Pond and
Head of Hummock Pond which have significant DO depletions in some years and
therefore higher variability between the methods (RDP up to 20%). Given that inclusion
of oxygen data did not generally change the bay health rank, the index calculated by
including DO appears to be most appropriate based upon 8 years of data, but both
approaches are developed each year and presented herein.
For the present analysis the standard Index (with DO) was used for assessment and the
Health Status was determined for each site based on the data collected during the
sampling events. The ranges of Index scores that fall within a particular Health Status
determination are given at the bottom of both Tables 7 and 8 with the Index values and
description for each monitoring station. Figures 20-24 show the distribution of Health
Status throughout each estuary based on each of the 8 years of monitoring (2010,
2012-2018). For the location maps, only the “with DO” index is shown as in 3 of the
56
past 5 years the inclusion of DO made no substantive difference in the index value and
in 2015 the difference was minor. Therefore, the Index maps shown for the “with DO”
index are comparable to other estuaries in the region for assessing Trophic Status.
Numerical results in the tables are color coded in the figures for ease of interpretation.
The colors of each triangle represent the Bay Health Index status of each site and follow
the designation scheme below:
Color Health Status
Blue High Quality
Blue/Yellow High-Moderate
Yellow Moderate
Yellow/Red Moderate/Fair
Red Fair/Poor
The integrated water quality scores, as represented by the Index were generally
consistent among all 8 years of monitoring. Although change at some sites was
observed, change was gradual and large inter-annual changes were typically related to
major management actions. This relative stability is typical as nutrient related health
does not generally change rapidly unless a significant alteration has occurred to the
watershed nitrogen loading or to tidal flushing of a basin (e.g. Hummock Pond, Long
Pond). However, 4 systems do appear to show a potential shift in nitrogen related
health over the past 8 years, Hither Creek, lower Hummock Pond and Long Pond and
after 8 years, slight improvements in Nantucket Harbor seem to be emerging (see
below). Based upon the results it is possible to assess the nutrient related health of the
basins within each of the 5 estuarine systems within the Nantucket Water Quality
Monitoring Program. The following assessments rely mainly on the Index "with DO"
scores as it appears to accurately represent current conditions:
Madaket Harbor
Madaket Harbor main basin in 2018 continued to support a high level of nutrient related water
quality. It has been the more enclosed basins of Hither Creek and Long Pond with their
reduced tidal flushing that have had nitrogen impairment problems. Water quality generally
changes gradually, unless there has been a major change in loading or flushing. Within the
Madaket Harbor/Long Pond watershed there has been a significant change in the nitrogen
sourced at the Town Landfill. The Landfill has recently been undergoing management actions
that reduce nitrogen loading to the groundwater, hence to upper Long Pond. It appears that
the long-term gradual reduction in TN levels within the upper portions of this complex estuary
is consistent with a lowering of watershed nitrogen loading. Over the 8 years of monitoring,
Hither Creek (Station 1), which receives discharge from Long Pond via Madaket Ditch, has
consistently supported the poorest “health” status within the Madaket Estuary (Table 8, 9,
Figure 20). Hither Creek is clearly nitrogen enriched and showing continuing impairment
based on a variety of parameters, but has clearly improved since 2010. Over the past 8 years
the Index indicates that this basin has improved slightly each year, going from fair-poor water
quality and improving in a step-wise manner to moderate water quality since 2014. The
exception was 2017 where TN levels rose, but stayed within the range that has developed over
the past 4-5 years, TN level declined to pre-2017 levels in 2018 and it is expected that this
variability will be reduced in coming years as the system reaches a new equilibrium with the
new lower landfill TN loading rate. The main basin of Madaket Harbor is showing relatively
57
high water quality in each year but also shows a possible improvement from 2010 to 2012 and
has been generally stable at high water quality in more recent samplings to 2018. It appears
that Station 2, near the outlet to Hither Creek can receive low quality waters on the ebb tide
from Hither Creek and that can modify water quality at this nearshore location (e.g. 2010). But
with improvements in the water quality in Hither Creek, its effect on water quality at Station 2 in
nearshore Madaket Harbor has been insufficient to effect the Harbor waters, which have
maintained high quality status since 2012. The offshore sites (3 & 4) support high quality
waters resulting from low nitrogen inputs and very high rates of water exchange. The 8 year
positive trend in health index is at least partially the result of the reduced loading from the
landfill to upper Long Pond and an improvement in the ebbing waters through Madaket Ditch.
This trend is consistent with the upper basin feeding Madaket Ditch. In 2014-2018 the
previously observed gradient in water quality metrics between the 2 Long Pond stations is only
periodically detectable, lessening concern over a potential tidal restriction. While a further
analysis of the mechanism underlying this periodic gradient would be useful, it is not needed at
this time, tracking the phenomenon through the on-going monitoring program should be
sufficient. If the improvement in Hither Creek becomes stabilized at the lower end of its range
(0.8 – 0.6 mg/L) and 2018 was 0.59 mg N/L, it is possible that the TMDL for Madaket Harbor
may require somewhat less nitrogen load reduction, making the success of other nitrogen
management actions (other than associated with the landfill and any needed septic system
work in Madaket) more certain. However, at this point it is likely that additional nitrogen
management will be required to meet the TMDL in Hither Creek as it remains of moderate
quality, although it appears the reduced load discharging from Madaket Ditch has resulted in
somewhat lower TN levels already. It should be noted that the “fair/poor" quality water
designation in Long Pond relates primarily to Long Pond being not supportive of eelgrass. But
the MEP and TMDL for Long Pond is based on infaunal animals living in the bottom sediments
(i.e. not eelgrass) so the water quality index should not cause concern. However, additional
analysis is required to determine if landfill activities will be sufficient to meet the TMDL for Long
Pond (see below). Additional study to clarify the drivers of the improvement (controllable such
as the landfill improvements or fertilizer management) will further assist in determining the
magnitude of septic system management as posited through the MEP analysis. This further
analytical effort is in progress in parallel with the Town’s actual and potential management
actions.
Long Pond
Long Pond is a large tributary basin to Madaket Harbor, which receives tidal flow
through the artificial connection of Madaket Ditch. Given the structure of the basin and
its watershed, Long Pond operates semi-independently from Madaket Harbor (Figure
20). Unlike Madaket Harbor which is marine, Long Pond is a brackish water system
resulting from mixing of groundwater inflows and salt water entering through its
restricted tidal channel (2018 salinity = 16 PSU). Long Pond’s Bay Health scores for
both stations (5 & 6) in the 8 years of monitoring (2010, 2012-2018) clearly indicate poor
nutrient related water quality. It is nearly certain that the water quality of Hither Creek is
partially dependent on the nitrogen load from Long Pond via Madaket Ditch during the
ebb tide. However, it should be noted that the TMDL targets restoration of sediment
animal communities (infauna) which do not require the same high water quality as
eelgrass.
Based upon the 2018 results and the 8 year time-series, it appears that the Town’s
management of the landfill, has reduced the nitrogen load from this source with the
associated observed lowering of TN levels. The connection is strengthened by the
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parallel timing of the landfill work and the lowering of TN in the adjacent waters, which
are only a short travel time from the landfill. While still small, the water quality Index for
Long Pond is starting to improve in response to the lower TN levels although the basin
remains impaired. TN levels in 2015-2017 and 2018 were almost half that of historical
and 2010 measurements although they still show inter-annual variations. While
continued monitoring will determine the final level of improvement, it does appear that
the reduction in N loading is occurring with beneficial effects. If TN levels stabilize at
2018 levels, the TN target in the TMDL will be achieved and in 2 years a habitat and DO
survey should be conducted to remove Long Pond from the MassDEP list of impaired
waters. It should be noted that the lack of major change in the Health Index for Long
Pond results in part from the relative coarseness of the Index, where sometimes large
index score changes are required to change the Index value. The analysis of key
metrics (Chlorophyll-a, water clarity-Secchi and total nitrogen) individually do show
improving water quality at stations 5 and 6 in 2012-2018 compared to 2010 and in the
MEP threshold analysis (see analysis and figures above).
Nantucket Harbor
Nantucket Harbor with Madaket Harbor are presently supporting the highest water
quality of Nantucket's estuaries. In 2018, all of the Nantucket and Polpis Harbor
stations were showing high water quality, slightly better than in 2017 Over the past 5
years, the main basin of Nantucket Harbor has supported high quality waters, with only
a periodic small level of decline in the uppermost basin, Wauwinet basin (Figure 21).
Wauwinet basin (station 3) had the highest average total nitrogen values for the Harbor
System in 2013 (0.415 mg/L) and 2015 (0.436 mg/L) consistent with its designation as
the surrogate for the sentinel station for the main basin and its documented past
eelgrass loss. It should be noted that in summer 2016, SMAST added station 2A and
established it as the official MEP sentinel station for which the nitrogen threshold was
established (refer to Figure 2, TN 0.399 mg/L), along with station 3 in order to meet
TMDL compliance monitoring criteria. Summer 2017 saw a slightly lower TN level at
station NAN-2A (0.368 mg/L) and 2018 lower still (0.337 mg/L). Summers 2016-2018
generally showed similar water quality in this basin as 2014 which showed improved
chlorophyll-a and TN levels versus prior years. The main driver of the poorer 2015
water quality was a phytoplankton bloom in the upper Harbor, which was relatively large
for Nantucket Harbor but only moderate for more enriched estuaries in the region.
While it is unclear if blooms will become more commonplace in the future, the levels in
2016 reflected more historic conditions and 2017/2018 again higher levels, clearly
these blooms need to be tracked. However, other activities associated with the Harbor
(additional sewer hookups, jetty improvement and oyster aquaculture) should result in
even lower TN and chlorophyll levels and reduce the likelihood of large phytoplankton
blooms in the future.
A similar pattern was seen in the enclosed sub-basins of Polpis Harbor (East and West)
as in the main basins of Nantucket Harbor. Polpis Harbor basins which after showing
moderate impairment in 2010 and 2012 have been showing only low to no impairment
in recent years, suggesting some improvement over historic conditions. As in
Wauwinet, Polpis Harbor showed 2018 & 2017 TN levels similar to 2010, 2012 and
2015, slightly higher than 2013 and 2014. This variation makes continued monitoring
essential to clarify any trends in water quality and linkages to stream nitrogen
discharges. Polpis Harbor did not show a phytoplankton bloom in 2015 and supported
only moderate-low phytoplankton biomass in 2015-2017 and 2018 (average <6 ug/L)
59
and appears to have attained generally high water quality status from moderate status
in 2010 and 2012. While the overall Nantucket Harbor System is generally supporting
high quality waters, the variability in the index in Wauwinet and Polpis basins should be
monitored to ascertain their long-term health and to determine the effectiveness of
restoration effort by the Town as it continues to move forward to meet the MassDEP
TMDL for this system. Overall, Nantucket Harbor appears to be relatively stable from
year to year with a gradual slight improvement with high index scores and higher level
metrics that support the contention that it is approaching its TMDL threshold, as is also
the case for Polpis Harbor. Equally important, although variable, it appears that slight
positive changes have been occurring in recent years.
Sesachacha Pond
Sesachacha Pond is a closed coastal salt pond that has its water quality managed by
periodically breaching the barrier beach to open the basin to tidal exchange with the
adjacent Atlantic Ocean waters. This management action serves to flush out nutrients
and organic matter on the ebb tides and receive saline waters on the flood tides.
Sesachacha Pond was evaluated under the Massachusetts Estuaries Project and a
nitrogen threshold (0.60 mg/L) was established for restoration of this system.
Additionally, the MEP analysis recommended an additional mid-summertime opening (if
logistically possible) as part of the pond management strategy to enhance flushing of
the pond and improve water quality to reach the threshold without any need for
infrastructure. The water quality monitoring program in 2010, 2012 and 2013 showed
that the pond nitrogen levels were converging on the 0.60 mg/L total nitrogen threshold
established by the MEP. Total nitrogen (TN) levels dropped significantly from historical
levels of 1.20 mg/L to ~0.68 mg/L in 2010 and 2012 and 0.67 mg/L in 2013, with
associated improvements in the levels of water clarity and chlorophyll-a. However, with
limited openings in 2014-2017, TN has risen and has returned to near historic levels,
~0.9 mg/L but with an improvement in 2018 (0.752 mg N/L), associated with continuing
impaired conditions. It appears that these changes relate to the quality of the pre-
summer opening. Given the 2010-2013 period when robust openings occurred, it
appears that a solid opening program has the capability to improve the water quality
metrics pond-wide to levels near the TMDL nitrogen threshold.
Based upon the Index alone, changes in water quality in Sesachacha Pond over the
2010-2013 period were stabilized at moderate impairment of this estuary, with more
recent monitoring 2015-2017 seeing a trend toward poor water quality conditions with a
rebound in 2018 (Figure 22) as TN levels rose (2015-2017) then declined (2018).
Additional higher level assessment of Sesachacha Pond initiated based on the 2010
monitoring results was conducted and confirmed that the pond was improving by 2013,
but was impaired in 2014 consistent with the monitoring results. The 2015-2018 data
underscores the reversal of improvement with phytoplankton biomass (as chlorophyll)
averaging >10 ug/L at all stations over the summer of 2018, 2017 and 2015 and 6-10
ug/L in 2016, consistent with nitrogen enrichment. The high chlorophyll values are
consistent with the elevated TN values in 2014-2018. It appears that like other
periodically opened ponds, the quality of the opening (amount of water exchanged)
controls the level of water quality in the following months. Fortunately, the data indicate
that attaining pond openings of the quality of 2012 and 2013 (done under Town
supervision) in the future may be sufficient to attain the TMDL for this system. In
addition the impaired but improved conditions in 2018, while high in TN, did not show
bottom water D.O. depletion, but with high chlorophyll-a, consistent with the MEP
60
threshold target of 0.60 mg N/L. A closer examination of the opening protocol and the
linkage to resultant water quality is needed for management of this system.
Hummock Pond
Hummock Pond is a closed coastal salt pond that is only periodically opened to the
ocean to flush out nutrients and organic matter on the ebb tide and receive low nutrient
saline waters on the flood tide. Creating sustained openings that are sufficient to allow
exchange of tidal waters for more than 4-5 days has been difficult for this system due to
its location on the coast and the large amount of sand migration in the coastal zone
which can rapidly reseal the inlet.
Hummock Pond is opened at a sufficient frequency to sustain salinity levels in the 4-8
ppt range, with only small inter-annual differences (2012 slightly higher than 2010).
The pond supports a small but clear salinity gradient from Station 1 nearest the ocean
to Station 7 in the uppermost basin (Head of Hummock). The present non-tidal state
and watershed nutrient inputs have resulted in moderate to poor nutrient related water
quality throughout the pond, with poor water quality conditions the present norm (2005-
2007, 2010, 2012, 2013, 2014, 2015). Unfortunately, in 2016 the pond appears to have
had lower water quality in its upper and mid reaches than in previous years, although
the lower basin did not show this inter-annual variation. Similarly, in 2017 and 2018
water quality declined further throughout most of the estuary, including the lower basin.
This resulted from the poor spring 2017 and 2018 opening which is reflected in the very
low salinities throughout summer 2017 (3.5 PSU) and 2018 (4.8 PSU). There is
generally a small gradient in water quality with moderate to poor conditions near the
ocean and poor conditions in the uppermost basins, but this collapsed to generally poor
water quality throughout the system in 2017 and 2018 (Figure 23). The uppermost
basin, Station 7, is approaching fresh/brackish conditions (4 ppt and 3.7 in 2018) and is
currently supporting mainly freshwater plant and animal habitats. This basin is
particularly eutrophic with phytoplankton blooms periodically exceeding 70 ug/L
(offshore waters are ~2 ug/L), although 2017 & 2016 showed levels ~15 ug/L and 21
ug/L in 2018 (consistent with is decline in salinity). This basin appears to have been
artificially connected to the adjacent estuary and is the recipient of much of the
freshwater inflow. It is one of the most highly eutrophic basins within the Town of
Nantucket with oxygen depletions to 3 mg/L. Due to the restricted tidal exchange even
the lower basin of Hummock Pond supports moderate to high average chlorophyll levels
~10 ug/L (2010, 2012, 2015). All of the metrics are consistent with a nutrient impaired
basin in all years. It should be noted that the lower third of the Hummock Pond Estuary
is currently supporting impaired benthic animal habitat even though conditions are the
"best" in the overall impaired system.
Based upon the monitoring results it is clear that the nutrient related health of Hummock
Pond is significantly related to the success of its periodic openings. As a result, the
Town and Nantucket Land Council undertook an analysis to refine the opening protocol
and gauge its effectiveness. The April 2013 opening was the first “experimental”
opening and it appeared to result in significant loss of TN and inflow of salt water. The
individual metrics and the Health Index for summer 2014 and 2015 appear to support
that tidal flushing was improved as nutrient related health was highest in 2014 and 2015
of the years monitored. It also appears that the continued successful inlet openings
from April 2014 into 2015 have resulted in additional improvements in water quality from
2014 to 2015, with 2015 showing the lowest TN levels in records back to 2005, although
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it is still above its threshold value to support high quality habitat. Unfortunately, this
pattern was not seen in the 2016-2018 water quality data, which showed further decline
in the upper and mid reaches, and even the lower basin. This opening program and
associated monitoring around the openings and in the summer will need to be used to
set metrics for a “successful” opening, to produce a simplified assessment protocol for
opening success and to document and further refine the opening protocol for the Town’s
on-going program. To date this joint effort has shown the potential for significant
benefits to Hummock Pond water quality and associated natural resources at low cost
to the Town, but successful openings appear to vary from year-to-year.
Miacomet Pond
Miacomet Pond is a closed coastal salt pond that is rarely (over a decade ago) opened
to the ocean to flush out nutrients and organic matter on the ebb tide and receive low
nutrient saline waters on the flood tide. As a result of the lack of tidal flow and
continuous groundwater inputs, the pond is presently freshwater, with salinity levels in
each of the past 7 years of monitoring of <0.5 ppt, reaching a low of 0.1 ppt, 2015-2017.
The present non-tidal state and extent of watershed nutrient inputs has resulted in a
decline in nutrient related water quality throughout the pond for both nitrogen and
phosphorus, with poor water quality and habitat impairment the present norm (Figure
24). This can be seen, for example, in the high chlorophyll levels (2010: 12-50 ug/L);
2012: 10-20 ug/L; 2013: 20-26 ug/L; 2014: 23-70 ug/L; 2015: 38-53 ug/L) several times
greater than the levels found in the high quality basins of Nantucket and Madaket
Harbors with a maximum in 2018 (25 ug/L) following highs in 2017 and 2016 (mean =
~14 ug/L). It appears that 2015 also had very high chlorophyll levels which were seen
in several of Nantucket’s estuaries, with conditions returning to more typical levels in
2016 and 2017. All of the metrics for Miacomet Pond are consistent with a highly
nutrient impaired basin. However, as the freshening of this basin has become complete
and sustained, it likely will have to be managed as a transitional freshwater system and
will need to be reassessed as such. As salt ponds freshen and become fresh ponds the
nutrient causing eutrophication can shift to phosphorus from nitrogen or become both
nitrogen and phosphorus (seasonally varying nutrient limitation). Since Miacomet Pond
may have storm over-wash in the future due to climate change related storm
intensification and sea level rise, it may be necessary for management to create both a
nitrogen and a phosphorus budget for this system and to conduct short-term incubations
to determine which nutrient is controlling pond health under present and varying salinity
conditions. None-the-less, phosphorus should be a part of pond management, with
phosphorus limitation to phytoplankton growth throughout Miacomet Pond in 2018 and
2016/2017, although only for the middle and lower pond in 2015. It is also important to
note that orthophosphate concentrations are quite low in the main basin (MP-1, MP-2)
generally <0.2 uM, such that adding phosphorus to this basin in mid-summer would
likely stimulate phytoplankton growth. In contrast, the uppermost reach generally
supports 2x-3x higher phosphate levels. It is likely that regions of the pond may be
sensitive to both nitrogen and phosphorus, such that overall both nutrients need to be
monitored and considered for management of Miacomet Pond, although phosphorus
management is clearly needed at this time.
Another challenge in managing Miacomet Pond is that it will be difficult for the Pond to
maintain itself as a purely freshwater system as storm over-wash and rising sea level
(as well as increasing storm intensity and frequency related to climate change) will tend
to periodically cause seawater intrusion into its lower basin. An analysis of future
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conditions for Miacomet Pond as sea level rises may be in order in the near future, as
remediation is considered. But at present the system is a highly nutrient impaired
aquatic system with poor water quality. It would be prudent for the Town to continue the
development of a management plan that takes into account not only the nutrient related
impairment of Miacomet Pond, but also accommodates the likely shifting between fresh
and salt water over the long term.
Recommendations for Future Monitoring (2018)
(1) As mentioned in previous years summaries of estuarine water quality across
Nantucket, due to the critical importance of dissolved oxygen to the ecological health of
an estuarine basin, additional data should be collected using high frequency automated
sensors when the low frequency sampling of the monitoring program suggests that a
problem may exist in a specific basin. At this point, Polpis Harbor and Wauwinet basin
in Nantucket Harbor and Hither Creek and Long Pond in the Madaket Harbor System
should be considered for this analysis at some time in the future (e.g. summer
2019/2020). It may also be timely to complete a higher level nutrient limitation
assessment of Miacomet Pond (if one hasn't already been completed) as that large “salt
pond” has been transitioning to a freshwater ecosystem and has been showing
consistently poor water quality and low trophic status indicative of an impaired habitat.
However, procedural steps should also be implemented to strengthen the oxygen data
base from the on-going monitoring program. In addition, Long Pond appears to be
maintaining a lowering of its nitrogen levels over the past 3 years (even though 2017 TN
levels are slightly higher than 2016), since the MEP full assessment of ecological
health. At present, it appears that the Town activities at the Landfill have lowered the
annual nitrogen input from this source lowering TN levels in Long Pond to ~0.6 mg N/L.
However, it is not known how long it will take for the full reduction to occur (as it appears
to be continuing into 2018) or what the new TN load from the landfill will be. In addition,
the extent of ecological improvement in Long Pond has not been fully assessed toward
meeting the restoration targets under the Clean Water Act, although the lowering of
nitrogen levels is a very positive result as also shown in the benthic infaunal survey
(November 2017).
Approaches to address these 2 issues are:
a) Deploying in situ oxygen meters (sondes) on the bottom of specific
estuaries at several strategic locations for the summer months when periodic
hypoxic or anoxic events in bottom waters can occur.
b) Long Pond is currently being reassessed with the MEP watershed-
embayment management model to determine if the new low TN levels are
likely sustainable. This effort uses Town evaluation of the current TN load to
the pond from the landfill. The monitoring results from 2012 - 2018 appear to
show a significant reduction in TN over historical conditions and 2010,
however, there is still some inter-annual variability as seen in the 2014-2018
results. At present, TN levels are the lowest on record. The landfill analysis
would allow prediction of how low TN levels should decline and should guide
the level of improvement expected in animal communities that was seen in
2017. It appears the Long Pond may be near compliance with its TMDL and
the Clean Water Act.
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(2) Results from monitoring streams discharging to Nantucket Harbor (specifically
Polpis Harbor) for which sampling was conducted only in 2015, 2016 and 2017
indicated that the nitrogen load from these streams can be significant relative to TN
levels within Polpis Harbor, but that flow is highly seasonal due to lower stream flow
volumes in summer. With increasing interest in lowering TN concentrations in Polpis
Harbor to meet the MEP established TN threshold, it is appropriate to extend stream
sampling into the 2018 sampling season given the high concentrations of total nitrogen
observed in 2017, 2016 and 2015 that are discharging to this tributary sub-embayment.
Moreover, given the complexity of the flow leaving the cranberry bogs up-gradient of
station 4 and the apparent split of the flow between east and west Polpis Harbor, a
detailed flow and load investigation should be undertaken. This is particularly important
as the load entering west Polpis Harbor past station WPF OUTLET appeared to be
nearly equal to the load entering the same portion of the system past station 6B
(however sources of load to both discharge points are different). The team is awaiting
the 2018 flow measurements for this analysis.
The stream monitoring coupled to the estuarine monitoring will allow a determination of
the linkage of stream discharge to TN levels in Polpis Harbor. Moreover, in regard to
stream sampling location ST4 and ST4A, TN load at ST4A compared to ST4 in 2017
ranged from ~12% to 25% (2016, ~12% to 38%) of the measured load at ST4, clearly
indicating a load difference with associated concentrations being measurably higher at
station 4A (1.478 mg/L) compared to station 4 (1.021 mg/L). In 2016 the average TN
concentrations were fairly similar (0.856 versus 0.776 mg/L). It is clear that there is
significant “pick-up” of flow and load to the stream occurring between the upper and
lower station, which dominates the stream discharge to the Harbor. The source of this
nitrogen should be investigated. In 2017 TN load for the period June through October
from ST4 accounted for 27% more load when compared to load leaving ST6B (June-
October load at ST4 = 198 kg vs ST6B = 156 kg). Additionally, load from WPH
OUTLET which enters west Polpis Harbor along with loads from ST6B is an equally
significant and possibly greater input to that portion of the Polpis Harbor system (June-
October load at WPH OUTLET = 152 kg vs ST6B = 156). The WPH OUTLET load
maybe greater than that measured at STA6B simply because there was no data for July
from the WPH OUTLET location. The initial data from 2016 indicated that TN load from
ST4 accounts for 61% to 70% of the combined load from streams ST4 and ST6B.
Given the 2017 and the 2016 results, it would be important to determine the watershed
areas contributing flow and load to ST4, ST6B and WPH OUTLET and to a lesser
extent from the upgradient bog system relative to reducing loads to Polpis Harbor. A
more detailed investigation is warranted in collaboration with the bog owner.
(3) Miacomet continues to show poor trophic conditions, high TN concentrations
(though slightly lower in 2017 at stations MP-1 and MP-2) through its basins (stations 1,
2, and 3 in 2018: 0.797, 0.864. 0.562 mg/L, 2017: 0.641, 0.584, 0.909 mg/L, 2016:
0.772, 0.669, 0.783 mg/L, respectively). Although TN levels were slightly lower in 2018
and 2017 at the middle and lower stations and lower in 2016 than in 2015, 2017 and
2018 levels are still indicative of a highly enriched condition, as also indicated by the
high total pigment concentrations (CHLA + pheophytin) in 2018 (19-36 ug/L), 2017 (10-
20 ug/L) and 2016. In light of yet another year of poor water quality in Miacomet Pond,
nitrogen and phosphorus budgets should be developed for Miacomet Pond and a
quantitative analysis of N versus P as the driving nutrient of eutrophication (if this has
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not been completed to date). Assessing the degree to which Miacomet Pond is N or P
limited and if the limitation tends more to one or the other constituent seasonally will be
critical to developing an effective management plan for this freshwater system coupled
with results from the 604b study prepared by Water Resources Services in conjunction
with the Town of Nantucket, Nantucket Pond Coalition and Nantucket Land Council to
address N/P limitation using groundwater wells.
(4) Pond Openings and Linkage to Water Quality. Hummock Pond appears to have its
nutrient related health significantly controlled by the success of its periodic openings.
As a result, the Town and Nantucket Land Council undertook an analysis of openings in
2013-2014 to refine the opening protocol and gauge its effectiveness. Critical elements
of the protocol were described in a technical memorandum developed by the Coastal
Systems Program which summarized two openings that were monitored to gauge
effectiveness. The opening protocol developed from this detailed work should continue
to be rigorously implemented as monitoring clearly shows that if specific conditions are
taken into consideration during a given opening, the ensuing opening tends to be
effective and have a clear positive impact on water quality. To date Hummock Pond
water quality has been shown to significantly improve under the revised opening
protocol by the Town. However, poor openings in 2017 have negated those
improvements. Even so, the monitoring indicates that both Sesachacha and Hummock
Ponds respond rapidly to changes in the level of annual flushing. It appears that only
~3 years of good flushing conditions can significantly improve pond water and habitat
quality. It also appears that pond openings may have to be coupled with other nitrogen
management alternatives to provide sufficient and long-lasting restoration.
Monitoring of the pond opening should be continued to evaluate the need for a mid-
summer opening (as was recommended by the MEP for the Sesachacha Pond system)
in this system and to improve the present protocol and to set metrics for evaluating a
“successful” opening in real time. Summer openings are hindered by restrictions due to
piping plover nesting, so it will be important to address this issue as possible over the
coming year. As previously stressed, monitoring openings should include wind and tidal
conditions during a given opening, pond water level before during and after the opening,
water quality before opening and after closure, size of opening {depth and width} and
number of days that tidal flows (in and out) occurred. It should be noted that timing and
construction of a proper pond opening is a difficult task to accomplish successfully,
especially through a large barrier beach like that separating Sesachacha Pond from the
ocean waters. The concept is to first document what has worked and what has not to
help make the efforts by the Town more beneficial. Future openings in 2018 should
continue to be monitored, as for Hummock Pond, to build a database of the details of an
effective opening in both Sesachacha Pond (and Hummock Pond). The Ponds Opening
Protocol should continue to be refined, with the goal of making future openings more
beneficial to the associated pond’s water quality and producing simplified approaches to
reduce the effort required for a successful opening. If it is determined that effective
openings can not be achieved for either closed pond but in particular Sesachacha Pond,
due to the dynamic nature of the barrier beaches being breached, then the town will
have to focus on reducing load to the ponds from the watershed or consider in situ
approaches for improving water quality. Oyster aquaculture as appropriate is being
investigated by towns on Cape Cod.
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Acknowledgements
This work is in collaboration with the Town of Nantucket through its Natural Resources
Department and the Marine Department. Special thanks go to Kaitlyn Shaw, Town of
Nantucket Water Resources Specialist and the Monitoring Program Coordinator, Assistant
Biologist Leah Cabral and to Jeff Carlson, Director - Natural Resources Department, for the
extra efforts that they have provided to ensure sampling success and the maintenance of a
high quality monitoring program. In addition, the Nantucket Land Council (Cormac Collier)
provided support for assessment of Hummock Pond openings and the development of the new
opening protocol, with additional support from Land Council staff. It is through the dedication
of these groups and the efforts of other environmental stewards in the Town of Nantucket that
Nantucket’s estuaries are being protected and in some cases already moving toward
restoration.
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Table 3a. Summary of Water Quality Parameters, 2018 Nantucket Sampling Program. Values are Station Averages of all sampling events,
June-September for sampling sites. Station NAN2A represent an MEP sentinel location for monitoring in Nantucket Harbor. NAN-2A is in a new
station that was first sampled in 2016 and is in a different location than NAN-2. It should be noted that in 2018, TP was only evaluated in the
stream sites, Sesachacha Pond, Hummock Pond, Long Pond and Miacomet Pond because of the expected low salinity values in those closed
ponds and the possibility that the Miacomet system maybe phosphorous limited rather than nitrogen limited. Further study should investigate the
possibility of P-limitation and TP paired with salinity should continue to be monitored during the summer 2019 field season.
20% Low20% Low
Summer 2018 Secchi Secchi Field Field Avg.Avg.Avg.Avg.Avg.Avg.Avg.Avg.Avg.Avg.Avg.Avg.Chla/T-Pig Avg.
average Depth DO DO Salinity PO4 NH4 Nox DIN DON TDN POC PON TON TN Chla Phaeo Ratio Total Pig
Embayment Sample ID (meters)% of WC Sat Sat (ppt)(mg/L)(mg/L)(mg/L)(mg/L)(mg/L)(mg/L)(mg/L)(mg/L)(mg/L)(mg/L)(ug/L)(ug/L)(ug/L)
(mg/L)(% sat)
HUMMOCK POND HUM7 1.333 35%3.835 41%3.74 0.0460 0.174 0.0079 0.181 0.285 0.466 2.395 0.423 0.707 0.889 13.09 8.71 0.60 21.80
HUMMOCK POND HUM8 0.383 32%5.139 62%4.03 0.0813 0.060 0.0306 0.090 0.514 0.604 11.792 2.884 3.398 3.488 46.80 3.85 0.92 50.65
HUMMOCK POND HUM5 0.708 42%8.159 92%4.90 0.0545 0.014 0.0101 0.024 0.403 0.427 2.162 0.376 0.779 0.804 13.63 7.17 0.66 20.80
HUMMOCK POND HUM3 0.938 52%6.756 82%5.55 0.0394 0.019 0.0113 0.030 0.418 0.448 2.183 0.409 0.826 0.856 13.77 4.17 0.73 18.76
HUMMOCK POND HUM1 0.950 38%5.640 67%5.81 0.0269 0.009 0.0035 0.013 0.393 0.406 2.082 0.375 0.768 0.781 13.31 3.89 0.77 17.21
LONG POND LONG6 0.900 100%3.266 42%16.79 0.0239 0.004 0.0008 0.005 0.333 0.338 1.339 0.216 0.549 0.554 8.38 1.51 0.85 9.90
LONG POND LONG5 1.000 86%5.969 79%15.43 0.0480 0.005 0.0005 0.006 0.317 0.323 2.051 0.297 0.614 0.620 9.81 2.19 0.82 12.00
MADAKET HARBOR MH1 1.494 84%5.194 68%30.12 0.0087 0.017 0.0013 0.018 0.197 0.217 1.062 0.199 0.396 0.414 8.68 6.11 0.59 14.79
MADAKET HARBOR MH2 1.813 100%5.468 73%29.81 0.0044 0.012 0.0008 0.012 0.161 0.173 0.637 0.107 0.281 0.293 4.32 1.89 0.70 6.21
MADAKET HARBOR MH3 2.188 95%5.706 76%31.42 0.0060 0.008 0.0004 0.008 0.134 0.142 0.446 0.076 0.210 0.218 2.80 0.69 0.80 3.48
MADAKET HARBOR MH4 3.875 70%6.216 83%31.51 0.0107 0.009 0.0004 0.009 0.114 0.123 0.364 0.058 0.172 0.181 2.89 0.48 0.86 3.37
MIACOMET POND MP3 1.113 89%4.869 51%0.10 0.0589 0.016 0.0393 0.055 0.300 0.355 1.286 0.207 0.507 0.562 9.19 9.82 0.48 19.01
MIACOMET POND MP1 1.050 62%7.085 79%0.41 0.0119 0.039 0.0057 0.045 0.458 0.503 1.574 0.294 0.752 0.797 15.78 4.29 0.79 20.07
MIACOMET POND MP2 1.544 56%5.332 58%0.55 0.0068 0.046 0.0049 0.050 0.456 0.507 1.905 0.356 0.812 0.863 27.78 8.12 0.77 35.90
NANTUCKET HARBOR NAN1 3.188 77%5.771 75%30.94 0.0167 0.006 0.0004 0.006 0.140 0.146 0.385 0.065 0.206 0.212 2.90 0.35 0.89 3.25
NANTUCKET HARBOR NAN2 2.588 65%5.394 80%30.98 0.0181 0.013 0.0003 0.014 0.145 0.159 0.591 0.097 0.242 0.256 3.86 1.23 0.76 5.09
NANTUCKET HARBOR NAN2A 2.113 59%5.134 77%31.00 0.0232 0.014 0.0004 0.014 0.193 0.207 0.865 0.130 0.323 0.337 7.00 1.52 0.82 8.52
NANTUCKET HARBOR NAN3 2.000 53%5.520 77%31.04 0.0191 0.011 0.0004 0.011 0.178 0.189 0.923 0.136 0.314 0.325 5.61 1.04 0.83 6.65
NANTUCKET HARBOR NAN4 2.775 62%6.214 86%31.02 0.0142 0.007 0.0004 0.007 0.125 0.132 0.393 0.059 0.185 0.192 2.77 0.55 0.83 3.32
NANTUCKET HARBOR NAN5 1.713 85%5.172 79%30.51 0.0204 0.010 0.0004 0.011 0.186 0.196 1.012 0.144 0.330 0.341 5.78 1.39 0.81 7.17
NANTUCKET HARBOR NAN6 2.250 87%5.115 79%30.71 0.0193 0.008 0.0004 0.009 0.172 0.180 1.092 0.147 0.318 0.327 7.22 1.40 0.84 8.62
NANTUCKET HARBOR NAN7 1.675 75%5.631 81%30.88 0.0174 0.018 0.0003 0.018 0.145 0.163 0.556 0.090 0.235 0.253 3.78 1.14 0.77 4.92
NANTUCKET HARBOR NAN8N 1.225 100%5.573 76%30.81 0.0162 0.005 0.0004 0.006 0.163 0.168 0.512 0.085 0.248 0.253 2.98 0.81 0.79 3.79
Nantucket Hrb. Stream Site ST4 0.264 100%2.290 24%0.10 0.0291 0.008 0.0093 0.017 0.496 0.513 3.144 0.233 0.729 0.746 4.29 2.59 0.62 6.87
Nantucket Hrb. Stream Site ST6 0.165 50%6.770 70%0.22 0.0450 0.011 0.0050 0.016 0.365 0.381 2.658 0.156 0.521 0.537 0.30 1.22 0.20 1.52
Nantucket Hrb. Stream Site WPH OUTLET 0.275 100%1.691 22%0.23 0.0310 0.028 0.0089 0.037 0.395 0.432 0.757 0.104 0.499 0.536 16.14 9.26 0.64 25.40
SESACHACHA POND SESA3 0.763 25%6.546 79%13.20 0.2826 0.013 0.0015 0.015 0.345 0.360 3.046 0.393 0.739 0.754 11.19 3.01 0.79 14.21
SESACHACHA POND SESA2 0.750 19%6.737 83%13.20 0.2830 0.016 0.0008 0.016 0.364 0.375 3.081 0.397 0.761 0.778 9.96 3.15 0.76 13.11
SESACHACHA POND SESA4 0.775 22%6.868 84%13.19 0.2568 0.007 0.0021 0.009 0.335 0.345 3.087 0.399 0.734 0.744 11.78 3.17 0.79 14.95
SESACHACHA POND SESA1 0.794 18%6.599 81%13.20 0.3007 0.018 0.0020 0.020 0.321 0.341 3.082 0.394 0.715 0.734 10.77 2.75 0.80 13.52
OLD NORTH WHARF - Oyster ORS2 1.313 100%5.500 71%30.88 0.0193 0.012 0.0004 0.012 0.151 0.163 0.533 0.084 0.235 0.248 2.66 0.81 0.77 3.48
SHIMMO Oyster ORS4 1.213 100%3.323 49%30.05 0.0202 0.013 0.0012 0.014 0.164 0.178 0.625 0.112 0.276 0.290 3.09 1.20 0.72 4.29
POLPIS Oyster ORS6 1.000 100%4.337 60%30.33 0.0246 0.009 0.0004 0.009 0.177 0.186 1.903 0.263 0.439 0.449 10.33 1.33 0.89 11.67
67
Table 3b. Summary of Water Quality Parameters, 2017 Nantucket Sampling Program. Values are Station Averages of all sampling events,
June-September for sampling sites. Station NAN2A represent an MEP sentinel location for monitoring in Nantucket Harbor. NAN-2A is in a new
station that was first sampled in 2016 and is in a different location than NAN-2. It should be noted that in 2017, TP was only evaluated in the
stream sites, Sesachacha Pond (pre and post opening, Hummock Pond (pre and post opening) and Miacomet Pond because of the expected
low salinity values in those closed ponds and the possibility that the Miacomet system maybe phosphorous limited rather than nitrogen limited.
Further study should investigate the possibility of P-limitation and TP paired with salinity should continue to be monitored during the summer
2018 field season.
20% Low 20% Low
(2017)Secchi Secchi Field Field Avg.Avg.Avg.Avg.Avg.Avg.Avg.Avg.Avg.Avg.Avg.Avg.Chla/T-Pig Avg.
average Depth DO DO Salinity PO4 NH4 Nox DIN DON TDN POC PON TON TN Chla Phaeo Ratio Total Pig
Embayment Sample ID (meters)% of WC Sat Sat (ppt)(mg/L)(mg/L)(mg/L)(mg/L)(mg/L)(mg/L)(mg/L)(mg/L)(mg/L)(mg/L)(ug/L)(ug/L)(ug/L)
(mg/L)(% sat)
HUMMOCK POND HUM7 1.81 48%4.67 51%2.11 0.134 0.095 0.004 0.098 0.392 0.490 1.551 0.254 0.646 0.789 11.470 2.438 0.825 13.908
HUMMOCK POND HUM8 0.53 38%6.86 75%2.68 0.123 0.017 0.014 0.031 0.647 0.678 2.788 0.512 1.159 1.200 33.279 11.694 0.740 44.974
HUMMOCK POND HUM5 0.66 32%6.99 77%3.39 0.131 0.039 0.005 0.044 0.577 0.621 2.134 0.382 0.959 1.024 23.904 4.068 0.855 27.972
HUMMOCK POND HUM3 0.83 42%8.36 92%4.10 0.091 0.014 0.004 0.018 0.540 0.558 2.069 0.414 0.954 0.980 22.450 5.163 0.813 27.613
HUMMOCK POND HUM1 0.94 38%7.02 78%4.40 0.079 0.090 0.007 0.096 0.598 0.695 1.719 0.317 0.915 1.078 21.228 4.847 0.814 26.075
LONG POND LONG6 0.85 84%6.51 79%14.61 0.016 0.066 0.009 0.076 0.467 0.543 1.130 0.166 0.634 0.712 9.467 1.452 0.867 10.919
LONG POND LONG5 0.71 67%6.54 78%13.28 0.030 0.005 0.006 0.010 0.480 0.491 2.135 0.375 0.855 0.867 23.565 2.628 0.900 26.192
MADAKET HARBOR MH1 1.47 72%4.91 64%25.78 0.016 0.018 0.011 0.030 0.361 0.391 0.838 0.165 0.527 0.570 9.937 1.833 0.844 11.769
MADAKET HARBOR MH2 1.68 100%6.24 83%29.96 0.014 0.015 0.003 0.018 0.279 0.297 0.452 0.080 0.359 0.386 5.666 1.210 0.824 6.877
MADAKET HARBOR MH3 2.20 94%6.05 77%30.83 0.013 0.021 0.002 0.022 0.236 0.258 0.409 0.069 0.304 0.341 1.600 0.976 0.621 2.576
MADAKET HARBOR MH4 2.83 58%6.15 80%30.90 0.016 0.021 0.001 0.022 0.193 0.215 0.414 0.073 0.266 0.306 3.189 0.842 0.791 4.030
MIACOMET POND MP3 1.35 84%5.25 59%0.10 0.050 0.044 0.027 0.071 0.414 0.485 2.496 0.386 0.800 0.909 11.287 7.352 0.606 18.638
MIACOMET POND MP1 1.63 87%2.86 33%0.24 0.004 0.004 0.002 0.006 0.461 0.467 1.140 0.170 0.633 0.641 10.636 3.784 0.738 14.420
MIACOMET POND MP2 2.23 74%3.08 32%0.33 0.003 0.003 0.002 0.005 0.439 0.445 0.990 0.138 0.577 0.584 7.273 2.002 0.784 9.275
NANTUCKET HARBOR NAN1 3.34 77%5.77 77%30.69 0.014 0.009 0.004 0.013 0.251 0.264 0.283 0.050 0.301 0.317 2.327 0.411 0.850 2.739
NANTUCKET HARBOR NAN2 3.04 63%5.69 77%30.68 0.016 0.014 0.003 0.017 0.227 0.243 0.309 0.054 0.280 0.302 2.406 0.742 0.764 3.148
NANTUCKET HARBOR NAN2A 2.44 43%5.66 77%30.80 0.018 0.030 0.004 0.033 0.249 0.283 0.490 0.086 0.335 0.377 4.412 1.062 0.806 5.474
NANTUCKET HARBOR NAN3 2.30 40%5.93 81%30.84 0.018 0.024 0.003 0.028 0.248 0.276 0.500 0.084 0.332 0.366 5.788 1.014 0.851 6.803
NANTUCKET HARBOR NAN4 2.56 53%6.15 82%30.77 0.014 0.007 0.002 0.010 0.211 0.221 0.353 0.064 0.275 0.288 3.822 0.545 0.875 4.367
NANTUCKET HARBOR NAN5 2.07 82%5.44 74%28.88 0.018 0.021 0.004 0.025 0.283 0.308 0.738 0.112 0.395 0.429 3.828 0.994 0.794 4.821
NANTUCKET HARBOR NAN6 2.18 80%5.60 77%30.34 0.015 0.019 0.003 0.022 0.264 0.286 0.766 0.112 0.376 0.405 5.400 1.112 0.829 6.512
NANTUCKET HARBOR NAN7 1.78 81%5.78 78%30.59 0.016 0.016 0.004 0.019 0.227 0.246 0.463 0.080 0.307 0.333 3.285 0.852 0.794 4.137
NANTUCKET HARBOR NAN8N 1.52 100%5.12 68%30.51 0.015 0.010 0.003 0.013 0.217 0.230 0.348 0.059 0.276 0.293 2.361 0.548 0.812 2.908
Nantucket Hrb. Stream Site ST4 0.18 83%3.11 31%0.08 0.070 0.012 0.006 0.018 0.945 0.963 0.701 0.053 0.998 1.021 1.284 0.544 0.702 1.828
Nantucket Hrb. Stream Site ST4A 0.25 63%1.21 12%0.10 0.039 0.025 0.009 0.034 1.387 1.422 0.457 0.056 1.444 1.478 0.102 0.847 0.107 0.949
Nantucket Hrb. Stream Site ST6 0.20 53%5.75 57%0.02 0.107 0.012 0.006 0.018 0.943 0.961 3.051 0.142 1.084 1.107 3.107 0.857 0.784 3.963
Nantucket Hrb. Stream Site WPH OUTLET 0.13 82%6.90 66%0.25 0.074 0.017 0.008 0.025 0.954 0.979 0.747 0.052 1.006 1.037 0.713 0.616 0.536 1.329
SESACHACHA POND SESA3 0.81 28%7.21 86%11.33 0.236 0.004 0.003 0.006 0.502 0.508 2.459 0.309 0.811 0.819 8.173 1.486 0.846 9.659
SESACHACHA POND SESA2 0.93 21%4.55 52%11.30 0.259 0.004 0.002 0.006 0.526 0.532 2.831 0.358 0.884 0.891 8.724 1.528 0.851 10.252
SESACHACHA POND SESA4 0.93 28%8.28 94%11.33 0.242 0.004 0.002 0.007 0.545 0.552 2.551 0.312 0.857 0.865 7.959 1.285 0.861 9.244
SESACHACHA POND SESA1 1.02 24%5.42 61%11.34 0.268 0.004 0.002 0.006 0.594 0.600 2.753 0.357 0.951 0.960 11.271 2.066 0.845 13.337
OLD NORTH WHARF - Oyster ORS2 1.21 100%5.14 69%30.33 0.016 0.031 0.005 0.036 0.233 0.268 0.294 0.048 0.289 0.329 2.477 0.529 0.824 3.006
SHIMMO Oyster ORS4 1.16 100%3.39 46%29.80 0.019 0.030 0.010 0.039 0.307 0.347 0.315 0.053 0.361 0.414 1.362 0.947 0.590 2.309
POLPIS Oyster ORS6B 0.93 100%3.70 49%29.75 0.019 0.038 0.005 0.043 0.323 0.366 0.431 0.074 0.397 0.460 1.804 0.960 0.653 2.764
68
Table 3c. Summary of Water Quality Parameters, 2016 Nantucket Sampling Program. Values are Station Averages of all sampling events,
May-September for sampling sites. Station NAN6, NAN 6C are duplicate samples (C = compliance sample) and represent an MEP sentinel
location for monitoring in Nantucket Harbor. This also applies to Station NAN-2A and 2AC, however, NAN-2A is in a new station and in a
different location than NAN-2. It should be noted that TP was only evaluated in the stream sites, Hummock Pond and Miacomet Pond because
of the expected low salinity values in those closed pond and the possibility that the Miacomet system maybe phosphorous limited rather than
nitrogen limited. Further study should investigate the possibility of P-limitation and TP paired with salinity should continue to be monitored during
the summer 2017 field season.
20% Low 20% Low
Secchi Secchi Field Field Avg.Avg.Avg.Avg.Avg.Avg.Avg.Avg.Avg.Avg.Avg.Avg.
Embayment Station ID average Depth DO DO Salinity PO4 TP NH4 Nox DIN DON TDN POC PON TON TN Total Pig
(2016)(meters)% of WC Sat Sat (ppt)(mg/L)(mg/L)(mg/L)(mg/L)(mg/L)(mg/L)(mg/L)(mg/L)(mg/L)(mg/L)(mg/L)(ug/L)
(mg/L)(% sat)
Hummock Pond HUM7 1.26 0.36 1.97 23%4.10 0.06 0.058 0.0550 0.0337 0.0887 0.39 0.48 1.08 0.19 0.58 0.67 5.91
Hummock Pond HUM8 0.44 0.35 4.18 49%4.70 0.06 NS 0.0393 0.0078 0.0471 0.62 0.67 2.94 0.52 1.15 1.19 15.71
Hummock Pond HUM5 0.62 0.30 2.93 34%6.40 0.03 0.054 0.0492 0.0029 0.0521 0.50 0.55 1.88 0.32 0.82 0.87 10.11
Hummock Pond HUM3 0.87 0.49 6.99 83%7.24 0.02 0.054 0.0042 0.0015 0.0056 0.45 0.45 1.20 0.20 0.65 0.65 5.34
Hummock Pond HUM1 0.92 0.45 6.16 75%8.17 0.02 0.050 0.0083 0.0024 0.0107 0.38 0.39 1.21 0.20 0.58 0.59 4.81
Long Pond LONG6 0.68 0.73 4.21 56%14.80 0.01 NS 0.0148 0.0044 0.0272 0.37 0.40 1.34 0.22 0.60 0.63 5.90
Long Pond LONG5 0.78 0.77 2.48 32%10.93 NS NS 0.0020 0.0021 0.0041 0.33 0.34 1.88 0.31 0.65 0.65 5.74
Madaket Harbor MH1C 1.75 0.76 4.27 62%27.32 0.03 NS 0.0164 0.0113 0.0277 0.27 0.32 0.79 0.15 0.41 0.44 3.68
Madaket Harbor MH1 1.63 0.82 3.38 46%26.64 0.03 NS 0.0359 0.0146 0.0505 0.27 0.32 0.71 0.12 0.38 0.43 3.50
Madaket Harbor MH2 1.60 1.00 4.94 69%29.31 0.01 NS 0.0144 0.0062 0.0206 0.21 0.23 0.60 0.10 0.32 0.34 2.56
Madaket Harbor MH3 2.14 1.00 5.31 72%31.36 0.01 NS 0.0094 0.0037 0.0132 0.18 0.20 0.47 0.07 0.25 0.26 1.71
Madaket Harbor MH4 3.06 0.79 5.92 80%31.92 0.01 NS 0.0077 0.0040 0.0116 0.16 0.17 0.33 0.05 0.21 0.22 1.50
Miacomet Pond MP3 0.93 0.55 5.24 59%0.10 0.01 0.065 0.0103 0.0077 0.0180 0.39 0.38 2.33 0.37 0.76 0.78 17.75
Miacomet Pond MP1 1.06 0.57 5.09 59%0.10 0.00 0.045 0.0063 0.0049 0.0112 0.41 0.42 2.08 0.35 0.76 0.77 12.28
Miacomet Pond MP2 1.33 0.54 4.86 57%0.10 NS 0.068 0.0083 0.0086 0.0169 0.38 0.40 2.00 0.27 1.27 0.67 12.26
Nantucket Harbor NAN3 2.34 0.46 4.61 66%31.73 0.02 NS 0.0081 0.0034 0.0115 0.23 0.24 0.72 0.11 0.34 0.36 3.79
Nantucket Harbor NAN6 1.98 0.80 4.81 69%31.23 0.02 NS 0.0101 0.0034 0.0135 0.24 0.25 0.92 0.12 0.39 0.37 4.61
Nantucket Harbor NAN6C 2.15 0.78 4.97 71%31.52 0.02 NS 0.0091 0.0021 0.0112 0.26 0.27 1.27 0.16 0.42 0.43 4.69
Nantucket Harbor NAN5 1.68 0.84 4.53 65%31.07 0.02 NS 0.0073 0.0040 0.0112 0.24 0.25 1.11 0.17 0.41 0.42 5.80
Nantucket Harbor NAN2 2.14 0.43 5.11 73%31.81 0.02 NS 0.0089 0.0026 0.0115 0.20 0.22 0.59 0.10 0.30 0.31 2.98
Nantucket Harbor NAN2A 2.34 0.47 4.37 62%31.97 0.02 NS 0.0090 0.0030 0.0121 0.25 0.27 0.92 0.13 0.39 0.40 4.99
Nantucket Harbor NAN2AC 2.30 0.56 4.26 60%32.02 0.03 NS 0.0085 0.0023 0.0108 0.25 0.26 1.13 0.17 0.42 0.43 5.29
Nantucket Harbor NAN7 1.91 0.81 5.12 73%31.71 0.02 NS 0.0072 0.0030 0.0102 0.18 0.19 0.87 0.11 0.29 0.30 3.74
Nantucket Harbor NAN1 2.31 0.64 5.14 73%31.90 0.02 NS 0.0075 0.0035 0.0110 0.23 0.24 0.43 0.08 0.31 0.32 2.02
Nantucket Harbor NAN8N 1.30 1.00 4.73 0.66 31.65 0.02 NS 0.0076 0.0045 0.0120 0.20 0.21 0.41 0.07 0.26 0.28 1.72
Nantucket Harbor NAN4 2.44 0.50 5.49 77%32.04 0.02 NS 0.0078 0.0031 0.0108 0.20 0.22 0.45 0.07 0.27 0.28 2.23
Nantucket Hrb. Stream Site STA4 0.28 0.46 5.48 53%0.15 0.07 0.105 0.0178 0.0027 0.0206 0.79 0.81 0.51 0.05 0.84 0.86 1.35
Nantucket Hrb. Stream Site STA4A 0.20 1.00 2.45 23%0.07 0.01 0.020 0.0194 0.0052 0.0246 0.71 0.74 0.42 0.04 0.75 0.78 3.41
Nantucket Hrb. Stream Site STA6B 0.20 0.78 4.72 47%0.00 0.11 0.220 0.0188 0.0059 0.0247 0.67 0.69 5.16 0.23 0.90 0.92 1.28
Sesachacha Pond SESA3 ND 0.23 5.90 74%11.59 0.22 NS 0.1232 0.0053 0.1285 0.45 0.57 3.43 0.43 0.90 1.01 6.46
Sesachacha Pond SESA2 ND 0.16 5.76 73%11.57 0.22 NS 0.1265 0.0061 0.1326 0.46 0.59 3.35 0.41 0.89 0.99 6.72
Sesachacha Pond SESA4 ND 0.21 5.94 74%11.59 0.22 NS 0.1165 0.0063 0.1228 0.47 0.59 3.35 0.42 0.91 1.00 6.18
Sesachacha Pond SESA1 0.79 0.15 5.58 70%11.55 0.21 NS 0.1012 0.0061 0.1072 0.46 0.57 3.55 0.44 0.90 1.01 6.85
Sesachacha Pond SESA1C 0.75 0.14 ND ND 11.30 0.17 NS 0.0014 0.0013 0.0027 0.48 0.49 3.13 0.39 0.88 0.88 10.22
OLD NORTH WHARF - Oyster ORS2 1.45 1.00 4.75 67%31.80 0.02 NS 0.0061 0.0054 0.0115 0.24 0.25 0.46 0.09 0.33 0.34 2.45
SHIMMO - Oyster ORS4 1.09 0.88 2.53 35%31.04 0.02 NS 0.0102 0.0038 0.0140 0.23 0.24 0.75 0.14 0.37 0.38 3.36
POLPIS - Oyster ORS6 1.14 0.92 4.46 63%31.60 0.02 NS 0.0232 0.0027 0.0259 0.27 0.30 1.09 0.14 0.54 0.47 4.93
69
Table 3d. Summary of Water Quality Parameters, 2015 Nantucket Sampling Program. Values are Station Averages of all sampling events,
May-September for sampling sites. It should be noted that TP was only evaluated in Miacomet Pond because of the expected low salinity values
in that closed pond and the possibility that the system maybe phosphorous limited rather than nitrogen limited.
2015 Seccchi Secchi 20% Low 20% Low
Sample ID Depth Depth as Field DO DO Sat Salinity PO4 TP NH4 Nox DIN DON TDN POC PON TON TN Total Pig
(meters)% of WC (mg/L)(%)ppt (mg/L)(mg/L)(mg/L)(mg/L)(mg/L)(mg/L)(mg/L)(mg/L)(mg/L)(mg/L)(mg/L)(ug/L)
HUM1 1.50 48%7.13 83%7.43 0.009 --0.004 0.003 0.007 0.350 0.357 1.097 0.182 0.532 0.539 10.50
HUM3 1.50 61%6.82 75%7.11 0.012 --0.005 0.006 0.011 0.402 0.413 1.236 0.209 0.610 0.622 9.41
HUM5 1.00 57%6.87 79%5.45 0.019 --0.005 0.003 0.008 0.359 0.366 1.206 0.192 0.550 0.558 8.58
HUM7 1.30 49%5.65 87%3.33 0.101 --0.089 0.030 0.119 0.349 0.468 0.996 0.154 0.502 0.621 7.07
HUM8 0.70 90%7.13 95%3.90 0.059 --0.005 0.011 0.016 0.366 0.381 1.230 0.195 0.560 0.576 12.82
LONG5 0.70 86%6.60 85%16.02 0.020 --0.012 0.004 0.016 0.378 0.395 2.025 0.302 0.681 0.697 8.95
LONG6 0.60 76%5.78 73%16.01 0.025 --0.006 0.002 0.008 0.369 0.377 1.619 0.280 0.649 0.656 10.78
MH1 1.80 77%4.88 68%29.28 0.021 --0.019 0.006 0.025 0.379 0.404 0.652 0.120 0.499 0.524 4.82
MH2 1.78 100%5.56 78%31.76 0.010 --0.012 0.030 0.042 0.289 0.331 0.482 0.088 0.376 0.418 3.07
MH3 2.40 97%6.57 90%32.00 0.010 --0.005 0.001 0.006 0.236 0.242 0.461 0.082 0.318 0.324 3.00
MH4 2.90 63%6.70 91%32.13 0.015 --0.006 0.002 0.008 0.269 0.277 0.301 0.051 0.321 0.328 2.54
MP1 0.90 50%6.94 83%0.10 0.008 0.084 0.025 0.013 0.038 0.592 0.630 3.870 0.666 1.259 1.297 46.52
MP2 0.70 32%6.10 82%0.11 0.009 0.090 0.042 0.011 0.053 0.593 0.646 3.726 0.671 1.264 1.318 53.40
MP3 1.40 54%7.91 91%0.10 0.017 0.136 0.021 0.057 0.077 0.396 0.473 2.878 0.518 0.914 0.992 37.91
NAN1 ND 62%6.29 88%32.13 0.024 --0.010 0.002 0.012 0.246 0.258 0.437 0.072 0.318 0.330 3.84
NAN2 2.65 49%5.95 85%32.25 0.019 --0.018 0.001 0.019 0.272 0.291 0.474 0.084 0.355 0.374 4.33
NAN3 1.45 27%5.89 86%32.37 0.026 --0.022 0.002 0.024 0.278 0.302 0.716 0.134 0.412 0.436 7.16
NAN4 3.80 65%6.58 91%32.14 0.019 --0.010 0.001 0.011 0.219 0.230 0.357 0.066 0.286 0.297 3.58
NAN5 1.65 85%5.32 76%31.92 0.021 --0.018 0.001 0.019 0.296 0.316 0.578 0.107 0.403 0.422 3.86
NAN6 1.95 73%5.64 81%31.94 0.019 --0.014 0.001 0.015 0.282 0.297 0.555 0.107 0.389 0.404 4.39
NAN7 1.45 76%6.20 86%32.00 0.019 --0.013 0.002 0.015 0.270 0.285 0.628 0.105 0.375 0.390 3.68
NAN8N 1.00 96%5.65 81%31.97 0.016 --0.007 0.002 0.009 0.227 0.236 0.435 0.077 0.304 0.313 3.08
SESA1 0.60 20%7.06 88%11.26 0.202 --0.006 0.003 0.008 0.479 0.487 3.193 0.431 0.910 0.918 11.45
SESA2 0.60 14%6.55 82%11.27 0.202 --0.003 0.002 0.005 0.448 0.454 3.100 0.417 0.865 0.870 10.39
SESA3 0.60 20%6.73 89%11.27 0.211 --0.003 0.002 0.006 0.476 0.481 3.146 0.429 0.904 0.910 11.33
SESA4 0.60 20%6.62 87%11.27 0.210 --0.003 0.003 0.007 0.507 0.514 3.028 0.405 0.912 0.919 11.10
70
Table 3e. Summary of Water Quality Parameters, 2014 Nantucket Sampling Program. Values are Station Averages of all sampling events,
May-September for sampling sites.
Seccchi Secchi
Depth Depth as 20% Low 20% Low Salinity PO4 NH4 Nox DIN DON TDN POC PON TON TN Total Pig
Sample ID (meters)% of WC DO (mg/L)Sat (%)ppt (mg/L)(mg/L)(mg/L)(mg/L)(mg/L)(mg/L)(mg/L)(mg/L)(mg/L)(mg/L)(ug/L)
HUM1 1.37 56%8.41 73%6.12 0.012 0.029 0.004 0.033 0.428 0.461 1.230 0.191 0.618 0.651 5.480
HUM3 1.05 61%8.35 75%5.72 0.012 0.023 0.006 0.029 0.402 0.431 1.329 0.212 0.614 0.643 5.262
HUM5 1.08 58%8.38 73%4.75 0.014 0.014 0.003 0.017 0.401 0.418 9.925 0.235 0.636 0.653 6.534
HUM7 0.94 41%8.44 77%2.65 0.047 0.054 0.020 0.071 0.444 0.515 2.400 0.358 0.801 0.873 11.875
HUM8 0.79 35%8.36 69%3.62 0.030 0.014 0.003 0.017 0.526 0.543 1.417 0.212 0.738 0.755 6.240
LONG5 0.75 75%7.62 53%14.12 0.032 0.080 0.012 0.092 0.975 1.066 2.354 0.415 1.390 1.481 8.988
LONG6 0.73 75%7.69 69%15.06 0.014 0.040 0.011 0.051 0.420 0.472 1.841 0.316 0.737 0.788 7.342
MH1 1.74 86%7.14 69%28.03 0.019 0.046 0.010 0.057 0.270 0.326 0.616 0.119 0.389 0.445 3.431
MH2 2.50 100%7.14 68%31.01 0.010 0.024 0.002 0.026 0.243 0.269 0.433 0.079 0.321 0.347 1.674
MH3 2.26 91%7.24 68%31.40 0.011 0.023 0.001 0.024 0.217 0.241 0.891 0.135 0.352 0.376 2.701
MH4 2.66 57%7.38 75%31.53 0.012 0.016 0.007 0.020 0.174 0.194 0.340 0.059 0.233 0.254 1.489
MP1 1.38 85%8.41 63%0.13 0.018 0.050 0.003 0.053 0.522 0.575 1.967 0.289 0.811 0.864 9.932
MP2 1.87 63%8.51 71%0.12 0.009 0.035 0.002 0.036 0.568 0.604 1.170 0.180 0.748 0.784 5.326
MP3 0.87 65%8.46 58%0.10 0.049 0.038 0.038 0.077 0.594 0.671 4.437 0.626 1.220 1.297 18.068
NAN1 3.35 64%7.23 77%31.36 0.015 0.017 0.002 0.019 0.201 0.220 0.380 0.063 0.265 0.284 1.311
NAN2 3.06 52%7.17 73%31.42 0.017 0.021 0.003 0.024 0.210 0.234 0.493 0.080 0.290 0.314 1.977
NAN3 3.10 51%6.98 75%31.42 0.016 0.020 0.001 0.020 0.225 0.245 0.631 0.100 0.325 0.345 3.125
NAN4 3.00 56%7.27 81%31.49 0.017 0.017 0.001 0.018 0.180 0.198 0.439 0.079 0.259 0.277 1.659
NAN5 2.13 90%7.10 69%30.99 0.016 0.016 0.003 0.019 0.248 0.267 0.756 0.122 0.370 0.389 3.223
NAN6 2.38 85%7.09 70%31.08 0.016 0.013 0.002 0.015 0.258 0.272 0.626 0.105 0.363 0.378 2.963
NAN7 1.79 80%7.26 73%31.23 0.020 0.022 0.001 0.023 0.168 0.190 0.656 0.104 0.271 0.294 2.691
NAN8N 2.09 99%7.16 74%31.29 0.016 0.015 0.002 0.017 0.188 0.205 0.356 0.062 0.250 0.267 1.267
SESA1 1.17 24%7.87 74%12.26 0.105 0.033 0.007 0.040 0.590 0.630 1.794 0.288 0.878 0.919 7.112
SESA2 1.23 24%7.86 70%12.23 0.111 0.038 0.010 0.049 0.531 0.579 2.154 0.352 0.883 0.931 7.116
SESA3 1.19 32%7.86 75%12.23 0.106 0.030 0.009 0.039 0.603 0.642 1.871 0.296 0.899 0.938 5.852
SESA4 1.22 32%7.83 72%12.25 0.108 0.030 0.009 0.039 0.572 0.611 1.808 0.290 0.862 0.902 5.407
71
Table 3f. Summary of Water Quality Parameters, 2013 Nantucket Sampling Program. Values are Station Averages of all sampling events,
May-October for estuarine and harbor sites.
2013 Secchi Secchi 20% Low 20% Low
Station Depth Depth Depth DO DO Salinity PO4 NH4 N0x DIN DON PON TON TN T-Pig
I.D.m m %WC mg/L %Sat ppt mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L ug/L
HUM-1 2.6 1.0 0.4 5.86 63%0.9 0.029 0.030 0.018 0.047 0.554 0.169 0.722 0.769 8.2
HUM-3 2.4 1.0 0.4 5.20 56%0.8 0.034 0.075 0.016 0.091 0.571 0.165 0.736 0.827 7.2
HUM-5 2.2 0.6 0.3 4.20 45%0.5 0.073 0.063 0.026 0.088 0.575 0.217 0.793 0.881 8.3
HUM-7 3.5 0.6 0.2 4.08 44%0.5 0.061 0.077 0.012 0.089 0.408 0.674 1.081 1.170 16.9
HUM-8 2.2 0.6 0.3 3.32 36%0.4 0.079 0.042 0.018 0.061 0.672 0.331 1.004 1.064 7.9
LONG-5 1.1 0.7 0.7 5.87 75%11.9 0.009 0.015 0.008 0.022 0.358 0.328 0.686 0.709 8.1
LONG-6 1.0 0.7 0.7 3.82 49%12.7 0.005 0.017 0.008 0.025 0.561 0.294 0.855 0.880 9.9
MH1 2.2 1.7 0.8 4.36 61%25.7 0.019 0.047 0.019 0.065 0.374 0.134 0.508 0.573 4.2
MH2 1.9 1.8 1.0 5.25 74%30.6 0.012 0.021 0.004 0.025 0.215 0.083 0.298 0.323 1.8
MH3 2.0 2.0 1.0 5.25 74%31.0 0.011 0.014 0.005 0.019 0.209 0.087 0.295 0.314 2.2
MH4 4.5 3.0 0.7 5.82 82%31.3 0.013 0.015 0.007 0.023 0.194 0.062 0.256 0.278 1.7
MP1 1.9 1.0 0.6 5.46 66%0.2 0.009 0.015 0.006 0.020 0.481 0.290 0.771 0.792 19.5
MP2 3.1 1.2 0.4 4.22 51%0.3 0.014 0.029 0.022 0.051 0.429 0.555 0.985 1.036 20.2
MP3 1.6 0.9 0.6 5.20 63%0.1 0.049 0.036 0.104 0.143 0.378 0.540 0.917 1.058 26.2
NAN1 5.5 3.2 0.6 5.10 74%31.2 0.014 0.015 0.003 0.018 0.182 0.062 0.244 0.262 2.6
NAN2 6.0 2.9 0.5 4.80 70%31.1 0.014 0.019 0.006 0.024 0.231 0.090 0.321 0.345 3.7
NAN3 6.2 2.6 0.4 3.48 50%30.9 0.019 0.016 0.004 0.020 0.241 0.154 0.395 0.415 6.4
NAN4 4.9 3.1 0.6 5.66 82%31.3 0.016 0.017 0.004 0.021 0.226 0.070 0.295 0.317 2.9
NAN5 2.3 1.9 0.8 3.90 57%30.1 0.018 0.012 0.005 0.017 0.208 0.159 0.368 0.385 5.6
NAN6 2.7 2.0 0.8 3.26 47%30.5 0.016 0.023 0.004 0.026 0.221 0.153 0.374 0.401 5.9
NAN7 2.5 1.9 0.8 5.02 73%31.1 0.013 0.013 0.004 0.017 0.183 0.122 0.305 0.323 4.6
NAN8 3.2 2.1 0.9 4.96 72%31.1 0.013 0.028 0.004 0.032 0.189 0.084 0.272 0.304 2.9
SES 1 4.9 2.1 0.4 5.83 79%17.1 0.044 0.045 0.011 0.055 0.533 0.125 0.658 0.714 4.7
SES 2 4.3 2.4 0.6 5.2 71%17.0 0.043 0.025 0.008 0.034 0.477 0.110 0.587 0.621 4.1
SES 3 4.5 2.5 0.6 5.6 75%17.0 0.046 0.031 0.011 0.042 0.512 0.109 0.621 0.663 3.8
SES 4 3.9 2.6 0.7 5.6 76%17.0 0.040 0.034 0.013 0.046 0.518 0.111 0.630 0.677 3.8
72
Table 3g. Summary of Water Quality Parameters, 2012 Nantucket Sampling Program. Values are Station Averages of all sampling events,
May-October for estuarine and harbor sites. Stream sites were sampled once in June (see Table 1b).
Table 3h. Summary of Water Quality Parameters, 2010 Nantucket Sampling Program. Values are Station Averages of all sampling events,
May-October for estuarine and harbor sites. Stream sites were sampled once in June (see Table 1a).
Secchi Secchi 20% Low 20% Low
Station Depth Depth DO DO Salinity PO4 NH4 N0x DIN DON PON TON TN T-Pig
I.D.m %WC mg/L %Sat ppt mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L ug/L
HUM-1 1.0 44%6.27 79%7.6 0.020 0.044 0.006 0.050 0.439 0.178 0.616 0.666 8.7
HUM-3 1.2 58%6.20 79%7.0 0.029 0.039 0.003 0.042 0.573 0.249 0.822 0.863 8.3
HUM-5 0.8 44%6.56 82%6.3 0.030 0.043 0.004 0.047 0.540 0.283 0.824 0.871 12.7
HUM-7 0.7 21%5.76 70%4.8 0.011 0.085 0.031 0.117 0.546 0.638 1.184 1.301 27.2
HUM-8 0.6 53%6.51 81%6.0 0.030 0.054 0.005 0.058 0.534 0.352 0.885 0.944 17.5
LONG-5 0.6 58%5.49 71%16.8 0.067 0.063 0.007 0.069 0.441 0.503 0.944 1.013 18.3
LONG-6 0.5 51%5.13 67%18.6 0.027 0.049 0.008 0.057 0.437 0.373 0.810 0.867 7.7
MH1 1.7 70%6.88 98%26.8 0.026 0.115 0.015 0.131 0.332 0.192 0.525 0.655 9.6
MH2 2.3 100%8.16 115%30.9 0.015 0.078 0.010 0.088 0.272 0.084 0.356 0.444 1.8
MH3 2.4 100%7.55 104%31.6 0.018 0.063 0.011 0.074 0.217 0.065 0.282 0.356 1.8
MH4 3.7 90%8.35 119%31.6 0.019 0.032 0.009 0.041 0.189 0.068 0.257 0.297 2.0
MP1 1.5 97%7.14 79%0.3 0.007 0.057 0.004 0.061 0.546 0.221 0.767 0.828 10.8
MP2 1.5 67%7.24 80%0.4 0.005 0.070 0.012 0.082 0.509 0.290 0.799 0.880 20.3
MP3 1.0 81%7.64 92%0.1 0.045 0.109 0.011 0.120 0.381 0.450 0.830 0.950 18.3
NAN1 3.5 73%5.22 74%31.6 0.020 0.045 0.011 0.056 0.210 0.070 0.279 0.335 3.8
NAN2 2.9 62%5.91 85%31.6 0.022 0.057 0.009 0.066 0.213 0.091 0.304 0.364 3.7
NAN3 2.4 40%5.86 87%31.8 0.027 0.035 0.008 0.044 0.261 0.117 0.371 0.411 4.0
NAN4 2.9 63%6.29 90%31.6 0.017 0.031 0.007 0.038 0.212 0.094 0.306 0.344 3.6
NAN5 1.7 76%5.96 83%31.5 0.019 0.046 0.007 0.053 0.233 0.133 0.366 0.419 14.9
NAN6 2.1 76%5.50 77%31.5 0.019 0.042 0.006 0.048 0.289 0.147 0.436 0.484 6.3
NAN7 2.0 80%6.10 86%31.5 0.021 0.049 0.008 0.057 0.217 0.105 0.323 0.379 4.2
NAN8 1.9 100%5.20 74%31.5 0.017 0.050 0.006 0.057 0.225 0.090 0.315 0.371 3.6
SES 1 2.3 51%5.49 77%24.7 0.064 0.042 0.010 0.051 0.497 0.130 0.627 0.678 5.8
SES 2 2.5 52%""24.7 0.065 0.087 0.014 0.101 0.405 0.120 0.525 0.627 5.1
SES 3 2.8 87%""24.7 0.063 0.053 0.007 0.060 0.417 0.107 0.524 0.584 4.2
SES 4 2.7 77%""24.8 0.062 0.060 0.010 0.070 0.456 0.142 0.599 0.668 4.5
73
Station ID
Secchi
Depth
(m)
Secchi
Depth
as
% WC
20% Low
D.O. (mg/L)
20% Low
% Sat
Salinity
ppt
PO4
mg/L
NH4
mg/L
NOX
mg/L
DIN
mg/L
DON
mg/L
PON
mg/L
TON
mg/L
TN
mg/L
Total
Pig
(ug/L)
HUM1 1.4 54.4% 4.81 56.0% 7.3 0.013 0.021 0.002 0.023 0.425 0.168 0.592 0.616 12.30
HUM3 1.3 61.5% 4.99 59.8% 6.4 0.012 0.022 0.003 0.025 0.380 0.184 0.564 0.589 11.04
HUM5 0.9 44.2% 4.65 56.1% 5.3 0.015 0.020 0.003 0.023 0.430 0.313 0.743 0.766 27.03
HUM7 0.9 23.4% 3.89 45.0% 4.0 0.284 0.070 0.069 0.139 0.628 1.020 1.647 1.786 67.66
HUM8 0.7 51.0% 4.80 56.5% 4.4 0.025 0.031 0.008 0.039 0.584 0.360 0.944 0.983 33.02
LONG5 0.6 48.5% 4.77 62.9% 16.0 0.071 0.009 0.002 0.011 0.480 0.894 1.374 1.385 18.08
LONG6 0.6 48.8% 4.76 62.9% 15.9 0.028 0.022 0.003 0.026 0.567 1.452 2.019 2.044 24.21
MH1 1.6 67.1% 3.00 40.1% 26.8 0.024 0.045 0.005 0.050 0.316 0.260 0.576 0.626 14.20
MH2 1.9 93.9% 3.52 47.9% 29.7 0.014 0.024 0.003 0.027 0.264 0.145 0.409 0.436 9.37
MH3 2.3 100.0% 4.39 55.5% 30.8 0.011 0.024 0.002 0.026 0.213 0.084 0.297 0.324 6.14
MH4 3.8 58.3% 4.27 55.6% 31.1 0.015 0.024 0.002 0.026 0.190 0.069 0.259 0.285 4.21
MP1 1.5 86.3% 5.43 54.0% 0.7 0.003 0.030 0.002 0.032 0.557 0.265 0.822 0.854 16.29
MP2 1.9 58.5% 5.70 62.8% 0.6 0.002 0.044 0.002 0.046 0.554 0.210 0.764 0.811 11.50
MP3 1.3 83.1% 4.93 56.6% 0.1 0.031 0.048 0.056 0.104 0.499 0.490 0.990 1.093 51.52
NAN1 4.5 84.8% 3.57 48.2% 31.0 0.016 0.027 0.003 0.030 0.218 0.084 0.302 0.332 4.00
NAN2 3.4 62.8% 3.45 47.4% 31.0 0.018 0.016 0.003 0.019 0.201 0.077 0.278 0.297 5.36
NAN3 2.8 49.2% 3.72 52.4% 30.9 0.022 0.027 0.003 0.030 0.251 0.111 0.362 0.392 7.58
NAN4 3.7 84.5% 3.89 52.2% 29.8 0.015 0.027 0.002 0.029 0.203 0.070 0.273 0.283 4.15
NAN5 2.0 98.0% 3.18 44.3% 30.4 0.017 0.027 0.007 0.034 0.248 0.149 0.397 0.431 11.31
NAN6 2.2 88.7% 3.26 45.7% 30.5 0.016 0.024 0.004 0.028 0.277 0.133 0.410 0.438 10.31
NAN7 2.1 92.5% 3.60 49.8% 30.9 0.016 0.023 0.003 0.026 0.244 0.106 0.351 0.377 7.35
NAN8 2.4 100.8% 3.65 50.0% 31.1 0.018 0.031 0.002 0.033 0.204 0.076 0.280 0.313 3.93
SESA1 1.6 32.9% 4.82 56.4% 11.9 0.051 0.018 0.003 0.021 0.441 0.222 0.663 0.684 8.00
SESA2 1.4 28.6% 4.83 56.4% 11.9 0.045 0.024 0.003 0.027 0.469 0.219 0.688 0.715 7.19
SESA3 1.5 36.6% 4.83 56.2% 11.9 0.049 0.021 0.006 0.028 0.449 0.223 0.672 0.700 7.61
SESA4 1.5 38.7% 4.83 56.4% 11.9 0.046 0.024 0.003 0.027 0.470 0.221 0.691 0.718 6.73
82 WAUWINET ND ND ND ND 18.2 0.071 0.122 0.004 0.126 0.611 0.108 0.719 0.845 40.70
STREAM1 ND ND ND ND 0.3 0.077 0.081 0.021 0.102 1.419 0.258 1.677 1.779 2.64
STREAM4 ND ND ND ND <0.1 0.163 0.039 0.008 0.048 1.092 0.061 1.153 1.200 1.18
STREAM6B ND ND ND ND <0.1 0.006 0.059 0.004 0.064 1.701 0.374 2.076 2.139 16.37
STREAM6C ND ND ND ND <0.1 0.132 0.097 0.003 0.100 0.375 0.156 0.532 0.632 7.41
STREAM8 ND ND ND ND 3.3 0.015 0.045 0.005 0.050 0.398 0.118 0.516 0.565 5.29
Secchi as % of WC is the % of the water column above the secchi depth, values of 100% means that the Secchi was at or below the bottom.
Lowest 20% of D.O. records for a site over the project period.
HUM = Hummock Pond, Long = Long Pond, MH = Madaket Harbor, MP = Miacomet Pond, NAN = Nantucket Harbor, SESA = Sesachacha Pond
74
Figure 15. Nitrogen species (mg/L) in Nantucket Harbor in summer 2018 compared to historical levels presented in panels below. Total
nitrogen is the sum of the inorganic and organic fractions (top line in each graph). All figures are to same scale.
75
Figure 15 cont'd. Comparison of nitrogen species (mg/L) in Nantucket Harbor in summers, 2010-2014 avg. (upper left, not including 2011);
2015 (upper right); 2016 (bottom left); 2017 (bottom right). Total nitrogen is the sum of the inorganic and organic fractions (top line in each
graph). All figures are to same scale.
76
Figure 15 cont'd. Nitrogen species (mg/L) in Hummock Pond in summer 2018 compared to historical levels presented in panels below.
Total nitrogen is the sum of the inorganic and organic fractions (top line in each graph). All figures are to same scale.
77
Figure 15 cont'd. Comparison of nitrogen species (mg/L) in Hummock Pond in summers, 2010-2014 avg. (upper left, not including 2011);
2015 (upper right); 2016 (bottom left); 2017 (bottom right). Total nitrogen is the sum of the inorganic and organic fractions (top line in each
graph). All figures are to same scale.
78
Figure 15 cont'd. Nitrogen species (mg/L) in Sesachacha Pond in summer 2018 compared to historical levels presented in panels below.
Total nitrogen is the sum of the inorganic and organic fractions (top line in each graph). All figures are to same scale.
79
Figure 15 cont'd. Comparison of nitrogen species (mg/L) in Sesachacha Pond in summers, 2010-2014 avg. (upper left, not including 2011);
2015 (upper right); 2016 (bottom left); 2017 (bottom right). Total nitrogen is the sum of the inorganic and organic fractions (top line in each
graph).
80
Figure 15 cont'd. Nitrogen species (mg/L) in Madaket Harbor in summer 2018 compared to historical levels presented in panels below.
Total nitrogen is the sum of the inorganic and organic fractions (top line in each graph). All figures are to same scale.
81
Figure 15 cont'd. Comparison of nitrogen species (mg/L) in Madaket Harbor in summers, 2010-2014 avg. (upper left, not including 2011);
2015 (upper right); 2016 (bottom left); 2017 (bottom right). Total nitrogen is the sum of the inorganic and organic fractions (top line in each
graph). All figures are to same scale.
82
Figure 15 cont'd. Nitrogen species (mg/L) in Long Pond discharging to Madaket Harbor in summer 2018 compared to historical levels presented
in panels below. Total nitrogen is the sum of the inorganic and organic fractions (top line in each graph). All figures are to same scale.
83
Figure 15 cont'd. Comparison of nitrogen species (mg/L) in Long Pond (Madaket Harbor System) in summers, 2010-2014 avg. (upper left,
not including 2011); 2015 (upper right); 2016 (bottom left); 2017 (bottom right). Total nitrogen is the sum of the inorganic and organic fractions
(top line in each graph). All figures are to same scale.
84
Figure 15 cont'd. Nitrogen species (mg/L) in Miacomet Pond in summer 2018 compared to historical levels presented in panels below. Total
nitrogen is the sum of the inorganic and organic fractions (top line in each graph). All figures are to same scale.
85
Figure 15 cont'd. Comparison of nitrogen species (mg/L) in Miacomet in summers, 2010-2014 avg. (upper left, not including 2011); 2015
(upper right); 2016 (bottom left); 2017 (bottom right). Total nitrogen is the sum of the inorganic and organic fractions (top line in each graph).
All figures are to same scale.
86
Figure 16. Summer 2018 TN concentrations compared to 2015, 2016, 2017 and average of 2010-2014
not including 2011.
87
Figure 16 cont'd. Summer 2018 TN concentrations compared to summer 2016, 2017 results for both
mid harbor station NAN2 and sentinel station NAN2A. Sampling at NAN2A was initiated in summer
2016.
88
Figure 16 cont'd. Summer 2018 TN concentrations compared to 2015, 2016, 2017 and average of
2010-2014 not including 2011.
89
Figure 16 cont'd. Summer 2018 TN concentrations compared to 2015, 2016, 2017 and average of
2010-2014 not including 2011.
90
Figure 16 cont'd. Summer 2018 TN concentrations in Madaket Harbor compared to 2015, 2016, 2017
and average of 2010-2014 not including 2011.
91
Figure 16 cont'd. Summer 2018 TN concentrations compared to 2010, 2012-2017 not including 2011.
92
Figure 16 cont'd. Summer 2018 TN concentrations compared to 2015, 2016, 2017 and average of
2010-2014 not including 2011.
93
Figure 17. Estuarine water quality monitoring station locations in the Nantucket Harbor
estuary system. Station labels correspond to those provided in Table 3 below. Red diamonds
indicate locations of MEP monitoring stations. Blue diamonds are locations of Town sampling.
Station 8 sampled in 2010, station 8N sampled in 2011, 2012, 2013, 2014, 2015, 2016, 2017 and
2018.
94
[1] It is almost certain that this does not represent the TN level in the inflow to Nantucket Harbor on the flood tide, but rather the 2012 data
is influenced by mixing with TN enriched out-flowing waters. An attempt to control for this issue was implemented in the 2013 monitoring
program.
Table 4. Comparison of MEP mean TN with Town data (values mg/L) from Nantucket Harbor. MEP data collected in the summers of 1988 -
1990 and 1992 - 1994 by the Woods Hole Oceanographic Institution, and between 1992 and 2005 by the Town of Nantucket Marine
Department and by the Nantucket Marine and Coastal Resources Department in summers 2010, 2012, 2013, 2014, 2015, 2016, 2017 and
2018.
Historical 2010 2010 2012 2013 2014 2015 2016 2017 2018
MEP Town Mean TN Mean TN Mean TN Mean TN Mean TN Mean TN Mean TN Mean TN
Mean TN ID
(mg/L)(mg/L)(mg/L)(mg/L)(mg/L)(mg/L)(mg/L)(mg/L)(mg/L)
Head of the Harbor - Upper 2 0.408 0.188 NA NS NS NS NS NS NS NS NS
Head of the Harbor - Mid Town 3 0.401 0.115 3 0.392 0.411 0.415 0.345 0.436 0.355 0.366 0.325
Head of the Harbor - Lwr 2A 0.339 0.07 NA NS NS NS NS NS 0.415 0.377 0.337
Pocomo Head 3 0.335 0.081 NA NS NS NS NS NS NS NS NS
Quaise Basin 3A+Town 2 0.336 0.112 2 0.297 0.364 0.345 0.314 0.374 0.314 0.302 0.256
East Polpis Harbor 4+Town 6 0.362 0.105 6 0.438 0.484 0.401 0.378 0.404 0.371 0.405 0.327
West Polpis Harbor 4A+Town 5 0.388 0.119 5 0.431 0.419 0.385 0.389 0.422 0.42 0.429 0.341
Abrams Point 5 0.335 0.06 NA NS NS NS NS NS NS NS NS
Monomoy 6 0.297 0.086 NA NS NS NS NS NS NS NS NS
Mooring Area 7+Town 1, 1A 0.326 0.106 1, 7 0.332,
0.377
0.335,
0.379
0.323,
0.323
0.294,
0.284
0.390,
0.330
0.304,
0.319
0.317,
0.333
0.212,
0.253
Nantucket Sound OS+Town 4 0.239 0.041 4 0.283 0.344[1]0.3171 0.277 0.297 0.283 0.288 0.192
Sub-Embayment Monitoring
Station s.d.
95
Figure 18. 2005 aerial photo showing MEP monitoring station location in Sesachacha Pond that was used in the water quality
analysis for the Massachusetts Estuaries Project. Station SES corresponds to SESA-1 in Tables 2a,b and Station 1 in Figure 3.
96
Table 5. Comparison of MEP mean values of TN with Town TN data (all values are mg/L) from Sesachacha Pond. MEP data were collected
in the summers of 1992 through 2005. Town data were collected in the summers of 2010, 2012, 2013 and 2014 by the Town of Nantucket
Marine and Coastal Resources Department. Values in 2010, 2012, 2013, 2014, 2015, 2016, 2017 and 2018 represent the average at Station
1, with the average of stations 1-4 in ( ).
Historical 2010 2012 2013 2014 2015 2016 2017 2018
MEP Mean TN Mean TN Mean TN Mean TN Mean TN Mean TN Mean TN Mean TN
Mean TN
(mg/L)(mg/L)(mg/L)(mg/L)(mg/L)(mg/L)(mg/L)(mg/L)(mg/L)
Sesachacha Pond 1.197 0.078 0.684
(0.704)
0.678
(0.639)
0.714
(0.669)
0.919
(0.922)
0.918
(0.904)
1.01
(1.003)
0.960
(0.884)
0.734
(0.752)
Sampling Station Location s.d.
97
Figure 19. Estuarine water quality monitoring station locations in the Madaket Harbor and Long Pond Systems.
98
Table 6. Comparison of MEP mean values of TN with Town TN data (all values are mg/L) from Madaket Harbor and Long Pond. MEP data
were collected by SMAST in the summers of 2002 through 2004. Town data were collected in the summers of 2010, 2012, 2013, 2014,
2015, 2016, 2017 and 2018 by the Town of Nantucket Marine and Coastal Resources Department.
Historical
MEP Mean TN 2010 2012 2013 2014 2015 2016 2017 2018
(mg/L)Mean TN Mean TN Mean TN Mean TN Mean TN Mean TN Mean TN Mean TN
(mg/L)(mg/L)(mg/L)(mg/L)(mg/L)(mg/L)(mg/L)(mg/L)
Madaket Harbor MEP M1 0.336 0.098
Madaket Harbor Town 4 0.285 0.297 0.278 0.254 0.328 0.219 0.306 0.081
Madaket Harbor MEP M2 0.395 0.083
Madaket Harbor Town 2 0.436 0.444 0.323 0.347 0.418 0.338 0.386 0.293
Madaket Harbor MEP M3 0.415 0.09
Madaket Harbor Town 3 0.324 0.356 0.314 0.376 0.324 0.26 0.341 0.218
Hither Creek MEP M4 0.581 0.193
Hither Creek MEP M5 0.78 0.178
Madaket Harbor MEP M6 0.347 0.067
Madaket Harbor MEP M10 0.422 0.127
MEP
M11+Town 1
Long Pond MEP LOPO1 1.058 0.404
Long Pond
MEP
LOPO2+Town 5 0.971 0.369 1.385 1.013 0.709 1.481 0.697 0.649 0.867 0.62
Long Pond MEP LOPO3 0.924 0.234
Long Pond
MEP
LOPO4+Town 6 0.894 0.278 2.044 0.867 0.88 0.788 0.656 0.629 0.712 0.554
North Head Long P.MEP LOPO5 0.954 0.271
0.57 0.414
Sub-Embayment Monitoring
Station s.d.
Hither Creek 0.62 0.215 0.626 0.655 0.573 0.445 0.524 0.434
99
Table 7. Comparison of TN concentrations collected in 2005 (Miacomet Pond) and 2007 (Hummock Pond) by Nantucket Marine and Coastal
Resources Department with Town TN data collected at both sites the summer of 2010, 2012, 2013, 2014, 2015, 2016, 2017 and 2018. All
values are mg/L. Note the very high TN in 2018 is associated with a phytoplankton bloom in July and August (total chlorophyll a reaching of
88 ug/L)
2018 2017 2016 2015 2014 2013 2012 2010
TN TN TN TN TN TN TN TN
(mg/L)(mg/L)(mg/L)(mg/L)(mg/L)(mg/L)(mg/L)(mg/L)
Mean Mean Mean Mean Mean Mean Mean Mean Mean S.D.
HUM1 0.781 1.078 0.594 0.539 0.651 0.769 0.666 0.616 0.751**0.374
HUM3 0.856 0.980 0.654 0.622 0.643 0.827 0.863 0.589 0.630**0.388
HUM5 0.804 1.024 0.868 0.558 0.653 0.881 0.871 0.766 ND ND
HUM7 0.889 0.789 0.673 0.621 0.873 1.170 1.301 1.786 1.283**0.969
HUM8 3.488 1.200 1.194 0.576 0.755 1.064 0.944 0.983 ND ND
MP1 0.797 0.641 0.772 1.297 0.864 0.792 0.828 0.854 0.842*0.191
MP2 0.863 0.584 0.669 1.318 0.784 1.036 0.880 0.811 0.855*0.213
MP3 0.562 0.909 0.783 0.992 1.297 1.058 0.950 1.093 0.280*0
*2005
data **2007
data
Hummock Pond and
Miacomet Pond Station ID's
2005/2007
TN
(mg/L)
100
Table 8a. 2018 Trophic Health Index Scores and status for water quality monitoring stations in
Nantucket estuaries based upon open water embayment (not salt marsh) habitat quality
scales. Index calculated with Dissolved Oxygen data (described in Howes et. al., 1999 at
www.savebuzzardsbay.org)
2018 Low20%2018
Secchi Oxsat DIN TON T-Pig EUTRO Health Status
EMBAYMENT SCORE SCORE SCORE SCORE SCORE Index
HUM1 28.6 64.1 100.0 0.0 0.0 38.5 Moderate-Fair
HUM3 27.7 88.5 67.0 0.0 0.0 36.6 Moderate-Fair
HUM5 10.3 100.0 75.7 0.0 0.0 37.2 Moderate-Fair
HUM7 49.6 2.7 0.0 0.0 0.0 10.5 Fair-Poor
HUM8 0.0 53.4 19.1 0.0 0.0 14.5 Fair-Poor
LONG5 31.7 83.4 100.0 0.0 0.0 43.0 Moderate
LONG6 25.2 7.1 100.0 11.7 0.9 29.0 Fair-Poor
MH1 56.7 64.9 89.5 54.5 0.0 53.1 Moderate
MH2 68.7 74.5 100.0 99.6 39.6 76.5 High
MH3 80.4 79.0 100.0 100.0 87.6 89.4 High
MH4 100.0 89.4 100.0 100.0 90.3 95.9 High
MP1 34.8 83.9 49.3 0.0 0.0 33.6 Moderate-Fair
MP2 58.7 45.3 44.3 0.0 0.0 29.7 Fair-Poor
MP3 38.4 29.3 40.5 22.1 0.0 26.0 Fair-Poor
NAN1 100.0 78.3 100.0 100.0 93.3 94.3 High
NAN2 90.8 85.3 100.0 100.0 56.0 86.4 High
NAN2A 78.2 81.0 99.1 81.3 13.3 70.6 High
NAN3 74.8 80.4 100.0 85.0 30.0 74.0 High
NAN4 95.2 94.5 100.0 100.0 91.6 96.3 High
NAN5 65.2 84.4 100.0 78.4 27.7 71.1 High
NAN6 82.1 83.2 100.0 83.2 12.4 72.2 High
NAN7 63.8 86.8 89.0 100.0 58.9 79.7 High
NAN8N 44.3 79.0 100.0 100.0 80.7 80.8 High
SESA1 17.4 86.9 84.9 0.0 0.0 37.8 Moderate-Fair
SESA2 13.9 89.3 93.3 0.0 0.0 39.3 Moderate
SESA3 14.9 84.4 97.1 0.0 0.0 39.3 Moderate
SESA4 15.9 91.8 100.0 0.0 0.0 41.5 Moderate
101
Table 8b. 2017 Trophic Health Index Scores and status for water quality monitoring stations in
Nantucket estuaries based upon open water embayment (not salt marsh) habitat quality
scales. Index calculated with Dissolved Oxygen data (described in Howes et. al., 1999 at
www.savebuzzardsbay.org).
2017 Low20%2017
EMBAYMENT Secchi Oxsat DIN TON T-Pig EUTRO Health Status
SCORE SCORE SCORE SCORE SCORE Index
HUM1 27.7 83.1 16.3 0.0 0.0 25.4 Fair-Poor
HUM3 19.8 100.0 89.1 0.0 0.0 41.8 Moderate
HUM5 5.6 80.3 50.3 0.0 0.0 27.2 Fair-Poor
HUM7 68.7 30.3 15.4 0.0 0.0 22.9 Fair-Poor
HUM8 0.0 78.1 65.5 0.0 0.0 28.7 Fair-Poor
LONG5 10.7 81.9 100.0 0.0 0.0 38.5 Moderate-Fair
LONG6 21.6 83.9 26.8 0.0 0.0 26.5 Fair-Poor
MH1 55.5 57.9 67.6 17.1 0.0 39.6 Moderate-Fair
MH2 63.8 89.5 88.2 67.5 31.1 68.0 High-Moderate
MH3 80.7 81.0 79.5 89.1 100.0 86.1 High
MH4 96.4 85.1 79.4 100.0 75.5 87.3 High
MP1 61.9 0.0 100.0 0.0 0.0 32.4 Moderate-Fair
MP2 81.4 0.0 100.0 5.2 6.2 38.6 Moderate-Fair
MP3 50.4 48.4 29.6 0.0 0.0 25.7 Fair-Poor
NAN1 100.0 80.6 100.0 90.6 100.0 94.2 High
NAN2 100.0 80.6 92.0 99.8 96.0 93.7 High
NAN2A 87.2 81.4 62.3 76.5 50.1 71.5 High
NAN3 83.6 87.0 70.7 77.6 32.0 70.2 High
NAN4 90.2 87.8 100.0 100.0 68.8 89.4 High
NAN5 76.9 76.3 75.6 54.9 60.6 68.8 High
NAN6 80.1 80.3 80.3 61.5 35.6 67.6 High-Moderate
NAN7 67.7 81.7 86.0 87.9 73.3 79.3 High
NAN8N 57.7 66.3 100.0 100.0 100.0 84.8 High
SESA1 32.9 51.7 100.0 0.0 0.0 36.9 Moderate-Fair
SESA2 26.9 33.3 100.0 0.0 0.0 32.0 Moderate-Fair
SESA3 18.4 94.0 100.0 0.0 2.9 43.1 Moderate
SESA4 27.0 100.0 100.0 0.0 6.5 46.7 Moderate
102
Table 8c. 2016 Trophic Health Index Scores and status for water quality monitoring stations in
Nantucket estuaries based upon open water embayment (not salt marsh) habitat quality
scales. Index calculated with Dissolved Oxygen data (described in Howes et. al., 1999 at
www.savebuzzardsbay.org).
Low 20%2016
Station Secchi Oxsat DIN TON T-Pig EUTRO Health Status
ID SCORE SCORE SCORE SCORE SCORE Index
HUM7 46.1 0.0 19.8 3.3 43.7 22.6 Poor
HUM8 0.0 24.2 47.3 0.0 0.0 14.3 Poor
HUM5 2.0 0.0 42.9 0.0 0.0 9.0 Poor
HUM3 23.1 90.3 100.0 0.0 52.1 53.1 Moderate
HUM1 26.6 76.8 100.0 3.5 60.8 53.5 Moderate
LONG6 7.8 40.7 71.2 0.0 43.8 32.7 Mod-Fair
LONG5 15.9 0.0 100.0 0.0 46.1 32.4 Mod-Fair
MH1C 66.5 54.4 70.4 48.5 83.1 64.6 High-Moderate
MH1 61.9 18.4 44.3 58.7 87.2 54.1 Moderate
MH2 60.9 66.7 83.2 83.6 100.0 78.9 High
MH3 79.0 71.8 100.0 100.0 100.0 90.2 High
MH4 100.0 86.2 100.0 100.0 100.0 97.2 High
MP3 26.9 47.8 89.0 0.0 0.0 32.8 Mod-Fair
MP1 35.5 47.0 100.0 0.0 0.0 36.5 Mod-Fair
MP2 49.2 42.7 91.9 0.0 0.0 36.8 Mod-Fair
NAN3 84.6 62.5 100.0 73.2 80.7 80.2 High
NAN6 74.2 66.6 100.0 56.3 64.2 72.3 High
NAN6C 79.3 70.6 100.0 47.7 62.9 72.1 High
NAN5 64.0 59.4 100.0 50.4 45.2 63.8 High-Moderate
NAN2 79.1 74.9 100.0 89.9 100.0 88.8 High
NAN2A 84.6 54.7 100.0 56.2 57.8 70.7 High
NAN2AC 83.5 50.9 100.0 45.9 52.8 66.6 High-Moderate
NAN7 72.0 73.4 100.0 93.5 81.8 84.1 High
NAN1 83.9 74.6 100.0 87.2 100.0 89.1 High
NAN8N 47.9 61.9 100.0 100.0 100.0 82.0 High
NAN4 87.1 81.2 100.0 100.0 100.0 93.7 High
STA4 0.0 35.6 83.3 0.0 100.0 43.8 Moderate
STA4A 0.0 0.0 75.4 0.0 89.4 33.0 Mod-Fair
STA6B 0.0 21.0 75.4 0.0 100.0 39.3 Mod-Fair
SESA3 100.0 75.4 3.7 0.0 36.3 43.1 Moderate
SESA2 100.0 73.5 2.4 0.0 33.0 41.8 Moderate
SESA4 100.0 76.7 5.7 0.0 39.9 44.5 Moderate
SESA1 17.1 69.5 11.6 0.0 31.4 25.9 Poor
SESA1C 13.9 100.0 100.0 0.0 0.0 42.8 Moderate
ORS2 54.8 63.5 100.0 79.2 100.0 79.5 High
ORS4 37.0 0.0 99.8 64.0 90.5 58.3 Moderate
ORS6 40.0 55.3 73.3 12.7 58.8 48.0 Moderate
103
Table 8c. 2015 Trophic Health Index Scores and status for water quality monitoring stations in
Nantucket estuaries based upon open water embayment (not salt marsh) habitat quality
scales. Index calculated with Dissolved Oxygen data (described in Howes et. al., 1999 at
www.savebuzzardsbay.org).
Low20%2015
Secchi Oxsat DIN TON T-Pig EUTRO Health Status
EMBAYMENT SCORE SCORE SCORE SCORE SCORE Index
HUM1 37.7 81.3 100.0 15.7 0.0 46.9 moderate
HUM3 37.2 73.6 100.0 0.0 5.1 43.2 moderate
HUM5 34.3 79.2 100.0 11.3 12.8 47.5 moderate
HUM7 62.7 81.4 7.1 23.3 28.7 40.6 moderate
HUM8 35.7 67.8 94.8 8.9 0.0 41.5 moderate
LONG5 22.0 82.4 93.1 0.0 9.2 41.4 moderate
LONG6 16.7 70.4 100.0 0.0 0.0 37.4 moderate/fair
MH1 63.3 51.7 74.5 24.2 60.6 54.9 moderate
MH2 81.4 72.2 52.4 61.2 98.1 73.1 High
MH3 80.0 89.5 100.0 83.3 99.9 90.5 High
MH4 99.0 98.5 100.0 82.2 100.0 95.9 Highe
MP1 19.0 75.1 56.6 0.0 0.0 30.1 Fair-Poor
MP2 17.9 79.8 42.1 0.0 0.0 28.0 Fair-Poor
MP3 24.5 95.0 25.8 0.0 0.0 29.1 Fair-Poor
NAN1 97.1 96.4 100.0 83.5 79.5 91.3 High
NAN2 92.0 89.1 86.6 68.7 69.6 81.2 High
NAN3 60.1 93.7 77.1 49.3 14.7 61.6 Moderate
NAN4 100.0 94.3 100.0 97.4 85.2 95.4 High
NAN5 67.6 79.2 85.7 52.2 79.2 72.8 High
NAN6 74.8 84.8 97.5 56.9 68.4 76.5 High
NAN7 68.7 91.8 96.4 61.7 83.1 80.4 High
NAN8N 79.7 83.5 100.0 89.3 97.8 90.1 High
ORS1 100.0 26.4 91.5 22.6 6.3 49.3 Moderate
ORS2 48.0 49.5 85.2 83.1 86.2 70.4 High
ORS3 0.0 33.8 34.6 40.4 91.0 40.0 Moderate
ORS4 0.0 35.0 57.4 60.6 83.8 47.4 Moderate
ORS5 21.6 56.5 99.9 35.8 100.0 62.8 High-Moderate
ORS6 0.0 53.3 64.6 19.0 72.5 41.9 Moderate
SESA1 25.5 88.1 100.0 0.0 0.0 42.7 Moderate
SESA2 9.6 88.5 100.0 0.0 0.0 39.6 Moderate
SESA3 9.6 98.4 100.0 0.0 0.0 41.6 Moderate
SESA4 7.8 93.5 100.0 0.0 0.0 40.3 Moderate
High Quality = >69; High-Moderate = 61-69; Moderate = 39-61; Moderate-Fair = 31-39;
Fair-Poor = <31
104
Table 8e. 2014 Trophic Health Index Scores and status for water quality monitoring stations in
Nantucket estuaries based upon open water embayment (not salt marsh) habitat quality
scales. Index calculated with Dissolved Oxygen data (described in Howes et. al., 1999 at
www.savebuzzardsbay.org).
Low20%2014
Secchi Oxsat DIN TON T-Pig EUTRO Health Status
EMBAYMENT SCORE SCORE SCORE SCORE SCORE Index
HUM1 51.3 74.7 62.7 0.0 50.0 47.7 Moderate
HUM3 34.8 78.3 68.2 0.0 53.3 46.9 Moderate
HUM5 36.5 73.8 91.7 0.0 35.3 47.5 Moderate
HUM7 28.1 81.0 29.3 0.0 0.0 27.7 Fair-Poor
HUM8 17.1 66.6 91.7 0.0 39.2 42.9 Moderate
LONG5 13.4 34.4 18.4 0.0 8.9 15.0 Fair-Poor
LONG6 11.8 67.6 43.7 0.0 25.7 29.7 Fair-Poor
MH1 66.1 67.6 39.4 56.9 88.8 63.7 High-Moderate
MH2 88.7 65.1 72.7 82.0 100.0 81.7 High
MH3 82.5 65.1 76.7 69.8 100.0 78.8 High
MH4 92.6 77.8 83.8 100.0 100.0 90.8 High
MP1 51.8 55.8 42.2 0.0 0.6 30.1 Moderate-Fair
MP2 70.6 70.1 58.6 0.0 52.3 50.3 Moderate
MP3 23.1 46.0 26.1 0.0 0.0 19.0 Fair-Poor
NAN1 100.0 81.3 86.9 100.0 100.0 93.7 High
NAN2 100.0 73.4 76.2 95.3 100.0 89.0 High
NAN3 100.0 77.5 83.7 80.6 96.6 87.7 High
NAN4 100.0 87.6 89.5 100.0 100.0 95.4 High
NAN5 78.8 68.0 87.6 63.3 94.0 78.4 High
NAN6 85.6 69.4 97.5 65.9 100.0 83.7 High
NAN7 67.9 74.0 79.1 100.0 100.0 84.2 High
NAN8N 77.6 75.7 91.2 100.0 100.0 88.9 High
SESA1 41.5 75.9 54.0 0.0 28.3 39.9 Moderate
SESA2 44.6 69.8 46.0 0.0 28.3 37.7 Moderate-Fair
SESA3 42.5 76.8 56.0 0.0 44.5 44.0 Moderate
SESA4 44.3 73.3 55.1 0.0 51.1 44.8 Moderate
High Quality = >69; High-Moderate = 61-69; Moderate = 39-61; Moderate-Fair = 31-39;
Fair-Poor = <31
105
Table 8f. 2013 Trophic Health Index Scores and status for water quality monitoring stations in
Nantucket estuaries based upon open water embayment (not salt marsh) habitat quality
scales. Index calculated with Dissolved Oxygen data (described in Howes et. al., 1999 at
www.savebuzzardsbay.org).
Low20%2013
Sta Secchi Oxsat DIN TON T-Pig EUTRO Health Status
ID SCORE SCORE SCORE SCORE SCORE Index
HUM-1 29.6 56.8 47.1 0.0 16.9 30.1 Fair-Poor
HUM-3 30.2 42.1 18.9 0.0 26.8 23.6 Fair-Poor
HUM-5 0.0 15.8 20.1 0.0 15.8 10.3 Fair-Poor
HUM-7 0.8 12.2 19.8 0.0 0.0 6.6 Fair-Poor
HUM-8 0.0 0.0 36.3 0.0 20.1 11.3 Fair-Poor
LONG-5 11.2 77.9 81.0 0.0 17.3 37.5 Moderate-Fair
LONG-6 9.3 25.0 74.8 0.0 1.1 22.0 Fair-Poor
MH1 64.5 52.5 33.4 22.0 71.2 48.7 Moderate
MH2 69.3 75.4 75.1 91.8 100.0 82.3 High
MH3 73.6 75.4 86.5 93.0 100.0 85.7 High
MH4 99.0 88.1 79.3 100.0 100.0 93.3 High
MP1 31.0 62.2 83.7 0.0 0.0 35.4 Moderate-Fair
MP2 41.9 30.5 44.1 0.0 0.0 23.3 Fair-Poor
MP3 27.3 56.2 0.0 0.0 0.0 16.7 Fair-Poor
NAN1 100.0 75.7 88.4 100.0 100.0 92.8 High
NAN2 97.3 68.2 75.7 82.0 83.1 81.3 High
NAN3 89.9 28.4 84.1 54.8 36.9 58.8 Moderate
NAN4 100.0 88.6 81.4 93.1 100.0 92.6 High
NAN5 70.7 42.6 91.3 64.3 48.0 63.4 High-Moderate
NAN6 76.1 20.5 72.4 61.9 44.2 55.0 Moderate
NAN7 70.0 73.8 90.9 88.6 64.4 77.5 High
NAN8 78.6 72.3 64.2 100.0 100.0 83.0 High
SES 1 78.9 83.6 40.3 0.0 62.4 53.0 Moderate
SES 2 86.4 70.2 61.6 2.8 73.5 58.9 Moderate
SES 3 88.0 77.5 52.5 0.0 80.7 59.7 Moderate
SES 4 92.1 79.3 47.9 0.0 79.9 59.8 Moderate
106
Table 8g. 2012 Trophic Health Index Scores and status for water quality monitoring stations in
Nantucket estuaries based upon open water embayment (not salt marsh) habitat quality
scales. Index calculated with Dissolved Oxygen data (described in Howes et. al., 1999 at
www.savebuzzardsbay.org).
Low20%
Station ID Year Secchi Oxsat DIN TON T-Pig EUTRO Health Status
SCORE SCORE SCORE SCORE SCORE Index
HUM-1 2012 30.8 84.2 45.0 0.0 12.0 34.4 Moderate-Fair
HUM-3 2012 41.0 83.4 52.8 0.0 16.0 38.6 Moderate-Fair
HUM-5 2012 17.5 89.3 47.3 0.0 0.0 30.8 Fair-Poor
HUM-7 2012 11.3 69.5 7.9 0.0 0.0 17.7 Fair-Poor
HUM-8 2012 1.0 87.1 38.0 0.0 0.0 25.2 Fair-Poor
LONG-5 2012 0.0 70.9 30.4 0.0 0.0 20.3 Fair-Poor
LONG-6 2012 0.0 64.1 39.3 0.0 21.9 25.1 Fair-Poor
MH1 2012 65.3 100.0 3.0 17.6 3.1 37.8 Moderate-Fair
MH2 2012 83.2 100.0 20.1 68.4 100.0 74.3 High
MH3 2012 84.8 100.0 27.7 99.0 100.0 82.3 High
MH4 2012 100.0 100.0 53.8 100.0 100.0 90.8 High
MP1 2012 55.3 84.6 36.2 0.0 0.0 35.2 Moderate-Fair
MP2 2012 55.4 85.3 23.2 0.0 0.0 32.8 Moderate-Fair
MP3 2012 31.0 100.0 6.7 0.0 0.0 27.5 Fair-Poor
NAN1 2012 100.0 76.4 40.2 100.0 79.4 79.2 High
NAN2 2012 98.9 92.6 32.5 89.4 83.0 79.3 High
NAN3 2012 85.2 96.0 50.7 63.0 76.7 74.3 High
NAN4 2012 98.5 99.8 57.2 88.3 84.0 85.5 High
NAN5 2012 65.1 90.5 42.3 64.9 0.0 52.6 Moderate
NAN6 2012 79.2 80.8 46.5 41.9 38.5 57.4 Moderate
NAN7 2012 75.0 95.0 39.4 81.3 72.6 72.7 High-Moderate
NAN8 2012 71.4 76.1 39.3 84.7 85.1 71.3 High
SES 1 2012 84.2 80.4 43.6 0.0 45.4 50.7 Moderate
SES 2 2012 88.9 80.4 14.1 17.4 55.7 51.3 Moderate
SES 3 2012 95.4 80.4 36.7 17.8 71.3 60.3 Moderate
SES 4 2012 93.6 80.4 30.2 0.3 66.2 54.2 Moderate
High Quality = >69; High/Moderate = 61-69; Moderate = 39-61; Moderate/Fair = 31-39;
Fair/Poor = <31
107
ID
Secchi
SCORE
Low20%
Oxsat
SCORE
DIN
SCORE
TON
SCORE
T-Pig
SCORE
EUTRO
Index Health Status
HUM1 54.0 41.6 100.0 4.3 2.4 40.4 Moderate
HUM3 48.5 49.6 75.2 8.2 0.0 36.3 Moderate-Fair
HUM5 25.9 41.7 77.7 0.0 0.0 29.0 Fair-Poor
HUM7 22.4 14.5 0.4 0.0 0.0 7.4 Fair-Poor
HUM8 12.2 42.6 55.2 0.0 0.0 22.0 Fair-Poor
LONG5 0.6 55.8 100.0 0.0 0.0 31.3 Moderate-Fair
LONG6 4.6 55.8 73.9 0.0 0.0 26.8 Fair-Poor
MH1 59.0 0.3 44.5 5.4 0.0 21.8 Fair-Poor
MH2 72.8 22.3 70.7 50.3 5.4 44.3 Moderate
MH3 83.3 40.5 72.7 92.1 40.5 65.8 High-Moderate
MH4 100.0 40.5 72.4 100.0 71.8 77.0 High
MP1 54.8 37.1 63.7 0.0 0.0 31.1 Moderate-Fair
MP2 70.3 55.6 47.9 0.0 0.0 34.8 Moderate-Fair
MP3 47.1 42.8 12.9 0.0 0.0 20.6 Fair-Poor
NAN1 100.0 23.0 66.7 90.1 76.1 71.2 High
NAN2 100.0 20.9 87.2 100.0 51.8 72.0 High
NAN3 95.5 33.4 66.4 66.3 23.0 56.9 Moderate
NAN4 100.0 32.8 68.0 100.0 73.0 74.8 High
NAN5 74.8 12.5 62.1 54.1 0.0 40.7 Moderate
NAN6 81.7 16.6 69.8 49.9 0.0 43.6 Moderate
NAN7 78.1 27.1 72.3 70.4 25.6 54.7 Moderate
NAN8 86.7 27.5 62.3 100.0 77.6 70.8 High
SESA1 62.1 42.3 82.2 0.0 18.5 41.0 Moderate
SESA2 54.3 42.3 71.4 0.0 27.4 39.1 Moderate
SESA3 55.9 42.0 70.2 0.0 22.7 38.2 Moderate-Fair
SESA4 54.8 42.5 71.3 0.0 32.9 40.3 Moderate
High Quality = >69; High/Moderate = 61-69; Moderate = 39-61; Moderate/Fair = 31-39;
Fair/Poor = <31
Table 8h. 2010 Trophic Health Index Scores and status for water quality monitoring stations in
Nantucket estuaries based upon open water embayment (not salt marsh) habitat quality
scales. Index calculated with Dissolved Oxygen data (described in Howes et. al., 1999 at
www.savebuzzardsbay.org).
108
Table 9a. 2018 Trophic Health Index Scores and status for water quality monitoring stations in
Nantucket estuaries based upon open water embayment (not salt marsh) habitat quality
scales. Index calculated without Dissolved Oxygen data (described in Howes et. al., 1999 at
www.savebuzzardsbay.org)
Low20%2018
2018 Secchi Oxsat DIN TON T-Pig EUTRO Health Status
EMBAYMENT SCORE SCORE SCORE SCORE SCORE Index
HUM1 28.6 64.1 100.0 0.0 0.0 32.1 Moderate-Fair
HUM3 27.7 88.5 67.0 0.0 0.0 23.7 Fair-Poor
HUM5 10.3 100.0 75.7 0.0 0.0 21.5 Fair-Poor
HUM7 49.6 2.7 0.0 0.0 0.0 12.4 Fair-Poor
HUM8 0.0 53.4 19.1 0.0 0.0 4.8 Fair-Poor
LONG5 31.7 83.4 100.0 0.0 0.0 32.9 Moderage-Fair
LONG6 25.2 7.1 100.0 11.7 0.9 34.4 Moderate-Fair
MH1 56.7 64.9 89.5 54.5 0.0 50.2 Moderate
MH2 68.7 74.5 100.0 99.6 39.6 77.0 High
MH3 80.4 79.0 100.0 100.0 87.6 92.0 High
MH4 100.0 89.4 100.0 100.0 90.3 97.6 High
MP1 34.8 83.9 49.3 0.0 0.0 21.0 Fair-Poor
MP2 58.7 45.3 44.3 0.0 0.0 25.8 Fair-Poor
MP3 38.4 29.3 40.5 22.1 0.0 25.2 Fair-Poor
NAN1 100.0 78.3 100.0 100.0 93.3 98.3 High
NAN2 90.8 85.3 100.0 100.0 56.0 86.7 High
NAN2A 78.2 81.0 99.1 81.3 13.3 68.0 High-Moderate
NAN3 74.8 80.4 100.0 85.0 0.0 64.9 High-Moderate
NAN4 95.2 94.5 100.0 100.0 91.6 96.7 High
NAN5 65.2 84.4 100.0 78.4 27.7 67.8 High-Moderate
NAN6 82.1 83.2 100.0 83.2 12.4 69.4 High
NAN7 63.8 86.8 89.0 100.0 58.9 77.9 High
NAN8N 44.3 79.0 100.0 100.0 80.7 81.3 High
SESA1 17.4 86.9 84.9 0.0 0.0 25.6 Fair-Poor
SESA2 13.9 89.3 93.3 0.0 0.0 26.8 Fair-Poor
SESA3 14.9 84.4 97.1 0.0 0.0 28.0 Fair-Poor
SESA4 15.9 91.8 100.0 0.0 0.0 29.0 Fair-Poor
109
Table 9b. 2017 Trophic Health Index Scores and status for water quality monitoring stations
in Nantucket estuaries based upon open water embayment (not salt marsh) habitat quality
scales. Index calculated without Dissolved Oxygen data (described in Howes et. al., 1999 at
www.savebuzzardsbay.org).
2017 Low20%2017
EMBAYMENT Secchi Oxsat DIN TON T-Pig EUTRO Health Status
SCORE SCORE SCORE SCORE SCORE Index
HUM1 27.7 83.1 16.3 0.0 0.0 11.0 Fair-Poor
HUM3 19.8 100.0 89.1 0.0 0.0 27.2 Fair-Poor
HUM5 5.6 80.3 50.3 0.0 0.0 14.0 Fair-Poor
HUM7 68.7 30.3 15.4 0.0 0.0 21.0 Fair-Poor
HUM8 0.0 78.1 65.5 0.0 0.0 16.4 Fair-Poor
LONG5 10.7 81.9 100.0 0.0 0.0 27.7 Fair-Poor
LONG6 21.6 83.9 26.8 0.0 0.0 12.1 Fair-Poor
MH1 55.5 57.9 67.6 17.1 0.0 35.1 Moderate-Fair
MH2 63.8 89.5 88.2 67.5 31.1 62.7 High-Moderate
MH3 80.7 81.0 79.5 89.1 100.0 87.3 High
MH4 96.4 85.1 79.4 100.0 75.5 87.8 High
MP1 61.9 0.0 100.0 0.0 0.0 40.5 Moderate
MP2 81.4 0.0 100.0 5.2 6.2 48.2 Moderate
MP3 50.4 48.4 29.6 0.0 0.0 20.0 Fair-Poor
NAN1 100.0 80.6 100.0 90.6 100.0 97.7 High
NAN2 100.0 80.6 92.0 99.8 96.0 96.9 High
NAN2A 87.2 81.4 62.3 76.5 50.1 69.0 High
NAN3 83.6 87.0 70.7 77.6 32.0 66.0 High-Moderate
NAN4 90.2 87.8 100.0 100.0 68.8 89.8 High
NAN5 76.9 76.3 75.6 54.9 60.6 67.0 High-Moderate
NAN6 80.1 80.3 80.3 61.5 35.6 64.4 High-Moderate
NAN7 67.7 81.7 86.0 87.9 73.3 78.7 High
NAN8N 57.7 66.3 100.0 100.0 100.0 89.4 High
SESA1 32.9 51.7 100.0 0.0 0.0 33.2 Moderate-Fair
SESA2 26.9 33.3 100.0 0.0 0.0 31.7 Moderate-Fair
SESA3 18.4 94.0 100.0 0.0 2.9 30.3 Moderate-Fair
SESA4 27.0 100.0 100.0 0.0 6.5 33.4 Moderate
110
Table 9c. 2015 Trophic Health Index Scores and status for water quality monitoring stations
in Nantucket estuaries based upon open water embayment (not salt marsh) habitat quality
scales. Index calculated without Dissolved Oxygen data (described in Howes et. al., 1999
at www.savebuzzardsbay.org).
No DO
Secchi DIN TON T-Pig EUTRO Health Status
EMBAYMENT SCORE SCORE SCORE SCORE Index
HUM1 37.7 100.0 15.7 0.0 38.3 Moderate
HUM3 37.2 100.0 0.0 5.1 35.6 Moderate-Fair
HUM5 34.3 100.0 11.3 12.8 39.6 Moderate
HUM7 62.7 7.1 23.3 28.7 30.4 Moderate-Fair
HUM8 35.7 94.8 8.9 0.0 34.9 Moderate-Fair
LONG5 22.0 93.1 0.0 9.2 31.1 Moderate-Fair
LONG6 16.7 100.0 0.0 0.0 29.2 Fair-Poor
MH1 63.3 74.5 24.2 60.6 55.6 Moderate
MH2 81.4 52.4 61.2 98.1 73.3 High
MH3 80.0 100.0 83.3 99.9 90.8 High
MH4 99.0 100.0 82.2 100.0 95.3 High
MP1 19.0 56.6 0.0 0.0 18.9 Fair-Poor
MP2 17.9 42.1 0.0 0.0 15.0 Fair-Poor
MP3 24.5 25.8 0.0 0.0 12.6 Fair-Poor
NAN1 97.1 100.0 83.5 79.5 90.0 High
NAN2 92.0 86.6 68.7 69.6 79.2 High
NAN3 60.1 77.1 49.3 14.7 50.3 Moderate
NAN4 100.0 100.0 97.4 85.2 95.6 High
NAN5 67.6 85.7 52.2 79.2 71.2 High
NAN6 74.8 97.5 56.9 68.4 74.4 High
NAN7 68.7 96.4 61.7 83.1 77.5 High
NAN8N 79.7 100.0 89.3 97.8 91.7 High
ORS1 100.0 91.5 22.6 6.3 55.1 Moderate
ORS2 48.0 85.2 83.1 86.2 75.6 High
ORS3 0.0 34.6 40.4 91.0 41.5 Moderate
ORS4 0.0 57.4 60.6 83.8 50.4 Moderate
ORS5 21.6 99.9 35.8 100.0 64.3 High-Moderate
ORS6 0.0 64.6 19.0 72.5 39.0 Moderate
SESA1 25.5 100.0 0.0 0.0 31.4 Moderate-Fair
SESA2 9.6 100.0 0.0 0.0 27.4 Fair-Poor
SESA3 9.6 100.0 0.0 0.0 27.4 Fair-Poor
SESA4 7.8 100.0 0.0 0.0 26.9 Fair-Poor
High Quality = >69; High-Moderate = 61-69; Moderate = 39-61; Moderate-Fair = 31-39;
Fair-Poor = <31
111
Table 9d. 2014 Trophic Health Index Scores and status for water quality monitoring stations
in Nantucket estuaries based upon open water embayment (not salt marsh) habitat quality
scales. Index calculated without Dissolved Oxygen data (described in Howes et. al., 1999
at www.savebuzzardsbay.org).
No DO
Secchi DIN TON T-Pig EUTRO Health Status
EMBAYMENT SCORE SCORE SCORE SCORE Index
HUM1 51.3 62.7 0.0 50.0 41.0 Moderate
HUM3 34.8 68.2 0.0 53.3 39.1 Moderate
HUM5 36.5 91.7 0.0 35.3 40.9 Moderate
HUM7 28.1 29.3 0.0 0.0 14.3 Fair-Poor
HUM8 17.1 91.7 0.0 39.2 37.0 Moderate-Fair
LONG5 13.4 18.4 0.0 8.9 10.2 Fair-Poor
LONG6 11.8 43.7 0.0 25.7 20.3 Fair-Poor
MH1 66.1 39.4 56.9 88.8 62.8 High-Moderate
MH2 88.7 72.7 82.0 100.0 85.8 High
MH3 82.5 76.7 69.8 100.0 82.2 High
MH4 92.6 83.8 100.0 100.0 94.1 High
MP1 51.8 42.2 0.0 0.6 23.6 Fair-Poor
MP2 70.6 58.6 0.0 52.3 45.4 Moderate
MP3 23.1 26.1 0.0 0.0 12.3 Fair-Poor
NAN1 100.0 86.9 100.0 100.0 96.7 High
NAN2 100.0 76.2 95.3 100.0 92.9 High
NAN3 100.0 83.7 80.6 96.6 90.2 High
NAN4 100.0 89.5 100.0 100.0 97.4 High
NAN5 78.8 87.6 63.3 94.0 80.9 High
NAN6 85.6 97.5 65.9 100.0 87.3 High
NAN7 67.9 79.1 100.0 100.0 86.8 High
NAN8N 77.6 91.2 100.0 100.0 92.2 High
SESA1 41.5 54.0 0.0 28.3 30.9 Moderate-Fair
SESA2 44.6 46.0 0.0 28.3 29.7 Fair-Poor
SESA3 42.5 56.0 0.0 44.5 35.8 Moderate-Fair
SESA4 44.3 55.1 0.0 51.1 37.6 Moderate-Fair
High Quality = >69; High-Moderate = 61-69; Moderate = 39-61; Moderate-Fair = 31-39;
Fair-Poor = <31
112
Table 9e. 2013 Trophic Health Index Scores and status for water quality monitoring stations
in Nantucket estuaries based upon open water embayment (not salt marsh) habitat quality
scales. Index calculated without Dissolved Oxygen data (described in Howes et. al., 1999
at www.savebuzzardsbay.org).
No DO
Sta Secchi DIN TON T-Pig EUTRO Health Status
ID SCORE SCORE SCORE SCORE Index
HUM-1 29.6 47.1 0.0 16.9 23.4 Fair-Poor
HUM-3 30.2 18.9 0.0 26.8 19.0 Fair-Poor
HUM-5 0.0 20.1 0.0 15.8 9.0 Fair-Poor
HUM-7 0.8 19.8 0.0 0.0 5.2 Fair-Poor
HUM-8 0.0 36.3 0.0 20.1 14.1 Fair-Poor
LONG-5 11.2 81.0 0.0 17.3 27.4 Fair-Poor
LONG-6 9.3 74.8 0.0 1.1 21.3 Fair-Poor
MH1 64.5 33.4 22.0 71.2 47.8 Moderate
MH2 69.3 75.1 91.8 100.0 84.0 High
MH3 73.6 86.5 93.0 100.0 88.3 High
MH4 99.0 79.3 100.0 100.0 94.6 High
MP1 31.0 83.7 0.0 0.0 28.7 Fair-Poor
MP2 41.9 44.1 0.0 0.0 21.5 Fair-Poor
MP3 27.3 0.0 0.0 0.0 6.8 Fair-Poor
NAN1 100.0 88.4 100.0 100.0 97.1 High
NAN2 97.3 75.7 82.0 83.1 84.5 High
NAN3 89.9 84.1 54.8 36.9 66.4 High-Moderate
NAN4 100.0 81.4 93.1 100.0 93.6 High
NAN5 70.7 91.3 64.3 48.0 68.6 High-Moderate
NAN6 76.1 72.4 61.9 44.2 63.6 High-Moderate
NAN7 70.0 90.9 88.6 64.4 78.4 High
NAN8 78.6 64.2 100.0 100.0 85.7 High
SES 1 78.9 40.3 0.0 62.4 45.4 Moderate
SES 2 86.4 61.6 2.8 73.5 56.1 Moderate
SES 3 88.0 52.5 0.0 80.7 55.3 Moderate
SES 4 92.1 47.9 0.0 79.9 55.0 Moderate
113
Table 9f. 2012 Trophic Health Index Scores and status for water quality monitoring stations
in Nantucket estuaries based upon open water embayment (not salt marsh) habitat quality
scales. Index calculated without Dissolved Oxygen data (described in Howes et. al., 1999
at www.savebuzzardsbay.org).
Station ID Year Secchi DIN TON T-Pig EUTRO Health Status
SCORE SCORE SCORE SCORE Index
HUM-1 2012 30.8 45.0 0.0 12.0 22.0 Fair-Poor
HUM-3 2012 41.0 52.8 0.0 16.0 27.4 Fair-Poor
HUM-5 2012 17.5 47.3 0.0 0.0 16.2 Fair-Poor
HUM-7 2012 11.3 7.9 0.0 0.0 4.8 Fair-Poor
HUM-8 2012 1.0 38.0 0.0 0.0 9.7 Fair-Poor
LONG-5 2012 0.0 30.4 0.0 0.0 7.6 Fair-Poor
LONG-6 2012 0.0 39.3 0.0 21.9 15.3 Fair-Poor
MH1 2012 65.3 3.0 17.6 3.1 22.3 Fair-Poor
MH2 2012 83.2 20.1 68.4 100.0 67.9 High-Moderate
MH3 2012 84.8 27.7 99.0 100.0 77.9 High
MH4 2012 100.0 53.8 100.0 100.0 88.4 High
MP1 2012 55.3 36.2 0.0 0.0 22.9 Fair-Poor
MP2 2012 55.4 23.2 0.0 0.0 19.7 Fair-Poor
MP3 2012 31.0 6.7 0.0 0.0 9.4 Fair-Poor
NAN1 2012 100.0 40.2 100.0 79.4 79.9 High
NAN2 2012 98.9 32.5 89.4 83.0 76.0 High
NAN3 2012 85.2 50.7 63.0 76.7 68.9 High-Moderate
NAN4 2012 98.5 57.2 88.3 84.0 82.0 High
NAN5 2012 65.1 42.3 64.9 0.0 43.1 Moderate
NAN6 2012 79.2 46.5 41.9 38.5 51.5 Moderate
NAN7 2012 75.0 39.4 81.3 72.6 67.1 High-Moderate
NAN8 2012 71.4 39.3 84.7 85.1 70.1 High
SES 1 2012 84.2 43.6 0.0 45.4 43.3 Moderate
SES 2 2012 88.9 14.1 17.4 55.7 44.1 Moderate
SES 3 2012 95.4 36.7 17.8 71.3 55.3 Moderate
SES 4 2012 93.6 30.2 0.3 66.2 47.6 Moderate
High Quality = >69; High/Moderate = 61-69; Moderate = 39-61; Moderate/Fair = 31-39;
Fair/Poor = <31
114
ID
Secchi
SCORE
DIN
SCORE
TON
SCORE
T-Pig
SCORE
EUTRO
Index Health Status
HUM1 54.0 100.0 4.3 2.4 40.1 Moderate
HUM3 48.5 75.2 8.2 0.0 33.0 Moderate-Fair
HUM5 25.9 77.7 0.0 0.0 25.9 Fair-Poor
HUM7 22.4 0.4 0.0 0.0 5.7 Fair-Poor
HUM8 12.2 55.2 0.0 0.0 16.9 Fair-Poor
LONG5 0.6 100.0 0.0 0.0 25.2 Fair-Poor
LONG6 4.6 73.9 0.0 0.0 19.6 Fair-Poor
MH1 59.0 44.5 5.4 0.0 27.2 Fair-Poor
MH2 72.8 70.7 50.3 5.4 49.8 Moderate
MH3 83.3 72.7 92.1 40.5 72.1 High
MH4 100.0 72.4 100.0 71.8 86.1 High
MP1 54.8 63.7 0.0 0.0 29.6 Fair-Poor
MP2 70.3 47.9 0.0 0.0 29.6 Fair-Poor
MP3 47.1 12.9 0.0 0.0 15.0 Fair-Poor
NAN1 100.0 66.7 90.1 76.1 83.3 High
NAN2 100.0 87.2 100.0 51.8 84.7 High
NAN3 95.5 66.4 66.3 23.0 62.8 High-Moderate
NAN4 100.0 68.0 100.0 73.0 85.3 High
NAN5 74.8 62.1 54.1 0.0 47.8 Moderate
NAN6 81.7 69.8 49.9 0.0 50.4 Moderate
NAN7 78.1 72.3 70.4 25.6 61.6 High-Moderate
NAN8 86.7 62.3 100.0 77.6 81.7 High
SESA1 62.1 82.2 0.0 18.5 40.7 Moderate
SESA2 54.3 71.4 0.0 27.4 38.3 Moderate-Fair
SESA3 55.9 70.2 0.0 22.7 37.2 Moderate-Fair
SESA4 54.8 71.3 0.0 32.9 39.8 Moderate
High Quality = >69; High/Moderate = 61-69; Moderate = 39-61;
Moderate/Fair = 31-39; Fair/Poor = <31
Table 9g. 2010 Trophic Health Index Scores and status for water quality monitoring stations
in Nantucket estuaries based upon open water embayment (not salt marsh) habitat quality
scales. Index calculated without Dissolved Oxygen data (described in Howes et. al., 1999
at www.savebuzzardsbay.org).
115
Figure 20. Madaket Harbor Eutrophication Index 2010 (top triangle) and 2018 (bottom triangle). Index was calculated with dissolved
oxygen. Colors indicate High (Blue), Moderate (Yellow), Fair/Poor (Red) nutrient related water quality.
Station 4
Station 3
Station 1
Station 5
Station 6
Station 2
Madaket Harbor and Long Pond
Eutrophication Index (2010, 2012 -2018)
Color Health Status
Blue High Quality
Blue/Yellow High-Moderate
Yellow Moderate
Yellow/Red Moderate/Fair
Red Fair/Poor
Bay Health Index
Top 2010
Mid 2015
Mid 2013
Mid 2012
Mid 2014
Mid 2016
Btm
2017 Mid
2018
116
Figure 21. Nantucket Harbor Eutrophication Index 2010 (top triangle) and 2018 (bottom triangle). Index was calculated with dissolved
oxygen. Colors indicate High (Blue), Moderate (Yellow), Fair/Poor (Red) nutrient related water quality. Station Nan-2A MEP Sentinel Station.
NAN 5-
NAN 7
(Childrens Beach)
NAN 4
NAN 3
NAN 6
NAN 2
-
NAN 8
(The Cut) 2010
NAN 1
Nantucket Harbor Eutrophication Index
(2010, 2012 -2018)
Color Health Status
Blue High Quality
Blue/Yellow High-Moderate
Yellow Moderate
Yellow/Red Moderate/Fair
Red Fair/Poor
NAN 8N (2012 –2018)
NAN-2A (2016-18)
MEP Sentinel Station
Bay Health Index
Top 2010
Mid 2015
Mid 2013
Mid 2012
Mid 2014
Mid 2016
Btm
2017 Mid
2018
117
Figure 22. Sesachacha Pond Eutrophication Index 2010 (top triangle) and 2018 (bottom triangle).
Index was calculated with dissolved oxygen. Colors indicate High (Blue), Moderate (Yellow), Fair/Poor
(Red) nutrient related water quality.
Station 2
Station 3
Station 4
Station 1
Sesachacha Pond
Eutrophication Index (2010, 2012 -2018)
Color Health Status
Blue High Quality
Blue/Yellow High-Moderate
Yellow Moderate
Yellow/Red Moderate/Fair
Red Fair/Poor
Bay Health Index
Top 2010
Mid 2015
Mid 2013
Mid 2012
Mid 2014
Mid
2016
Btm
2017
Mid
2018
118
Figure 23. Hummock Pond Eutrophication Index 2010 (top triangle) and 2018 (bottom triangle). Index
was calculated with dissolved oxygen. Colors indicate High (Blue), Moderate (Yellow), Fair/Poor (Red)
nutrient related water quality.
Station 3
Station 1
Station 5
Station 8
Station 7
Station 2
Station 4
Station 6
Hummock Pond
Eutrophication Index
(2010, 2012 -2018)
Color Health Status
Blue High Quality
Blue/Yellow High-Moderate
Yellow Moderate
Yellow/Red Moderate/Fair
Red Fair/Poor
Station 9
Bay Health Index
Top 2010
Mid 2015
Mid 2013
Mid 2012
Mid 2014
Mid 2016
Btm 2017
119
Figure 24. Miacomet Pond Eutrophication Index 2010 (top triangle) and 2018 (bottom triangle). Index
was calculated with dissolved oxygen. Colors indicate High (Blue), Moderate (Yellow), Fair/Poor (Red)
nutrient related water quality.
MP 3
MP 2
MP 1
Color Health Status
Blue High Quality
Blue/Yellow High-Moderate
Yellow Moderate
Yellow/Red Moderate/Fair
Red Fair/Poor
Bay Health Index
Top 2010
Mid 2015
Mid 2013
Mid 2012
Mid 2014
Mid 2017
Btm 2018
2016 Mid