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Technical Memorandum
FINAL
Water Quality Monitoring and Assessment of the
Nantucket Island-Wide Estuaries and Salt Ponds
Update 2014
To:
Town of Nantucket
Marine and Natural Resources Department
2 Bathing Beach Road
Nantucket, MA 02554
Rosemary Blacquier
Woodard & Curran
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
April 28, 2015
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The Technical Memorandum on the 2014 Nantucket Water Quality Monitoring Program is
organized consistent with previous SMAST water quality monitoring summaries (2010, 2012 and
2013) for direct comparison to data from the previous years of monitoring. However, the 2014
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 and including it
herein is unnecessarily redundant. The 2014 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
2. Trophic State: Water Quality/Eutrophication Status
3. Recommendations for Future Monitoring
As in previous years, the 2014 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, which are the target of resource
management. As in previous years (2010, 2012, 2013), the approach utilized for the
collection and analysis of 2014 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 more broadly 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 formulate
appropriate nutrient management strategies. This allows individual towns such as
Nantucket to directly benefit from lessons learned throughout the wider region.
As in past years, UMD-SMAST Coastal Systems Program (CSP) scientists focused
primarily on the analysis of samples collected from the field effort and data analysis and
program coordination while the Nantucket Natural Resources Department focused
primarily on coordination, field sampling and data collection on physical parameters.
The goals of the monitoring program remain unchanged from previous years, primarily to:
1. determine the present (2014) ecological health of each of the main salt ponds and
estuaries within the Town of Nantucket,
2. 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
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3. provide the foundation (and context) for detailed quantitative measures to derive
and assess potential alternatives for nutrient and resource management, as
appropriate.
This latter point (3) is critical for restoration planning should a system be found to be
impaired or trending toward impairment and is also is required to develop cost-effective
targeted solutions.
As was the case in 2010, 2012, and 2013, sampling in 2014 took place during the
summer/early fall months (May-September). 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 (2014), Table 1b (2013), Table 1c (2012) and Table 1d (2010).
Samples collected in 2014 were obtained from the same sampling station locations and
the same depths as in previous years to maximize cross comparability. 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 is presented in tabular form in Appendix A of previous years technical
memoranda and are not being reproduced again herein.
The physical parameters measured in the estuaries during the 2014 sampling season
included: total depth, Secchi depth (light penetration), temperature, conductivity/salinity
(YSI meter), general weather, wind force and direction, dissolved oxygen levels and
observations of moorings, birds, shell fishing and unusual events (fish kills, algal blooms,
etc). Laboratory analyses for estuaries included: salinity, nitrate + nitrite, ammonium,
dissolved organic nitrogen, particulate organic carbon and nitrogen, chlorophyll-a and
pheophytin-a and orthophosphate. As in the summer of 2013, the water quality
monitoring undertaken in 2014 was focused entirely on estuarine stations. In addition, 33
field duplicates 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. 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 resources. At present, activities to lower nitrogen
enrichment and its negative impacts to water quality are underway associated with
Nantucket Harbor (jetties and sewers), Long Pond (landfill), Sesachacha Pond
(openings), Hummock Pond (refined opening protocol). All estuaries should also benefit
from the recent fertilizer application by-law. As a result, it is anticipated that the
monitoring data will begin reflecting these activities. As noted below summer 2014
appears to have improved water quality for Nantucket Harbor and Hummock Pond and
continuing change (+/- depending on the year and based on specific parameters such as
CHLA, nutrients or eutrophication index) in Long Pond and Sesachacha Pond (see
below).
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Table 1a. Sampling Schedule for 2014 Nantucket Water Quality Monitoring Program
Note: * The September 15 sampling of Nantucket Harbor only involved one station (NAN-4).
Table 1b. Sampling Schedule for 2013 Nantucket Water Quality Monitoring Program
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
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
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Table 1c. Sampling Schedule for 2012 Nantucket Water Quality Monitoring Program
Table 1d. Sampling Schedule for 2010 Nantucket Water Quality Monitoring Program
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
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
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Figure 1. Madaket Harbor and Long Pond sampling stations 2010, 2012, 2013 and 2014.
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Figure 2. Nantucket Harbor sampling stations 2014. Station NAN-8 (the cut) was only sampled in 2010 and location changed in 2011
and 2012, 2013. Nantucket Harbor and Polpis Harbor each have nitrogen thresholds in the MassDEP/USEPA TMDL for this system.
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Figure 3. Sesachacha Pond sampling stations 2010, 2012, 2013, 2014.
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Figure 4. Hummock Pond sampling stations 2010, 2012, 2013 and 2014. Station 7 is in Head of Hummock, a kettle pond connected by
an artificial channel to the estuary and a configuration that maintains a salinity gradient from Station 7 to Station 8.
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Figure 5. Miacomet Pond sampling stations 2010, 2012, 2013 and 2014.
Station 3
Station 1
Station 2
Station 3
Station 1
Station 2
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Summary of 2014 Water Quality Results for Nantucket Sampling
While there were some localized areas of interest (Sesachacha and Long Ponds and
Hummock Pond, see below), the overall trends in water quality observed in 2014 follow
and expand the pattern observed in 2010, 2012 and 2013. Water samples collected
from May through September in the estuarine systems indicate that organic nitrogen
(dissolved + particulate) dominates the Total Nitrogen pool (79%-97% overall, 91%-95%
2014 alone), while bio-available nutrients in the form of nitrite and nitrate (NOx) and
ammonium (NH4) account for only 5%-21% (5%-9%, 2014) of the Total Nitrogen pool
(Table 2a,b,c,d, Figure 12). 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 nutrient
critical for management.
The predominance of organic nitrogen in the Total Nitrogen (TN) pool in these systems
would indicate that they are effectively converting the bioavailable inorganic forms of
nitrogen into organic forms (e.g. phytoplankton). Where tidal flushing is effective, much
of this 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 2014 (Table 2a), as noted in
prior years as well (Table 2b,c,d). Consistent with the water clarity, corresponding
chlorophyll-a pigment concentrations were lowest (2-4 ug/L) in these well flushed
systems (Table 2a,b,c,d, Figure 6,7). The level of variation is common and underscores
the need for multi-year monitoring to establish trends.
Figure 6. Average Chlorophyll-a (CHLA) concentrations by station in the well flushed
Nantucket Harbor system during the summer 2014 sampling season. Stations Nan-5
and 6 are in Polpis Harbor the rest relate to the main basin. Note that 2014 levels were
consistently lower than in prior years.
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Figure 7. Average Chlorophyll-a (CHLA) concentrations by station in the well flushed
Madaket Harbor system during the summer 2014 sampling season. Stations MH-2,3,4
are in the main open basin, MH-1 is the MEP sentinel station in Hither Creek. The 2010
blooms have not been as prevalent in recent years.
Both well flushed basins tended to have generally lower phytoplankton biomass
(chlorophyll-a) in 2014 than previous years. This was most striking in Nantucket Harbor
where average chlorophyll-a at each station was lower than in each of the prior years,
while in Madaket Harbor the levels were in amongst the lowest. This is consistent with
the higher water clarity as in these systems turbidity is primarily the result of organic
particulate, e.g. phytoplankton. The parallel measurements of total nitrogen (TN) are
generally consistent with the chlorophyll-a results, showing lower TN levels with lower
chlorophyll-a levels (see below). This is particularly apparent in Nantucket Harbor and
provides additional evidence that nitrogen is the eutrophying nutrient in these systems.
Where tidal flushing is more restricted in Long, Hummock and Miacomet Ponds (0.4-1.2
m) and in the improving Sesachacha Pond (2 meters), these moderate levels of water
clarity are consistent with the chlorophyll-a concentrations that have a higher (2x-3x)
average (compared to Nantucket and Madaket Harbors), 2.6 ug/L (max. 19.94 ug/L), 4.4
ug/L (max. 17.61 ug/L), 4.2 ug/L (max. 19.9 ug/L) and 3.0 ug/L (max. 7.9 ug/L),
respectively (Table 2a, Figures 8,9,10,11). These general patterns were also observed
in the monitoring results of the prior year (2013, 9 ug/L, 8-17 ug/L, 20 ug/L and <5 ug/L),
however, it should be noted that the chlorophyll-a levels in Long Pond, Hummock Pond
and Miacomet Pond appear to be lower when compared to 2013 average values. In
Sesachacha Pond chlorophyll-a levels have risen slightly in 2014 compared to 2013
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(maybe due to a less effective opening compared to the prior years of 2012 and 2013).
The multi-year results clearly show that 2010 was a poor water quality year as was also
seen in the open basins, e.g. Madaket Harbor. Over the past 4 years, chlorophyll-a
levels in Long Pond, Hummock Pond, Miacomet Pond and Sesachacha Pond have
dropped but do show variation (e.g. Sesachacha Pond 2014 > 2013). However, due to
increased flushing with openings, Sesachacha Pond is much improved over its status
during the MEP assessment that indicated chlorophyll-a levels generally >20 ug/L,
frequently >60 ug/L and blooms as high as 100 ug/L. These levels far exceed the
recent monitoring results, 2010-2014, with station averages generally 3-8ug/L. These
lower chlorophyll-a values are associated with lower TN levels, most likely the result of
comparatively improved openings.
Long Pond also showed lower chlorophyll-a in 2013 and 2014 than prior years, a trend
noted previously and possibly a result of activities at the landfill. However, Long Pond
continues to be eutrophic and impaired. Miacomet Pond which is not open to tidal flows
and has become very fresh, showed the highest chlorophyll-a levels of all the estuaries
and levels indicative of eutrophic conditions for both fresh and salt water (>10 ug/L).
Overall, 2014 supported slightly lower chlorophyll-a levels, likely for meteorological
reasons, there was no clear inter-annual pattern.
Hummock Pond showed significantly lower total chlorophyll-a levels in summer 2014
than prior years. The 2014 results were the lowest levels measured over the 4 years of
monitoring. While one year does not make a trend, nor are the results necessarily going
to be repeated in 2015 there is a potential explanation. The Town and Nantucket Land
Council entered into a project to refine the opening protocol for Hummock Pond to
maximize the amount of tidal flushing achieved by the openings. The April 2014 opening
of Hummock Pond was moderately successful and lowered TN levels in the pond and
raised its salinity. The hydraulic gradient on opening was ~1.7 m, which provided a
good head of water for opening the channel. It is possible that the combination of the
good opening and the meteorological conditions that appear to have supported higher
water quality in most of the estuaries in summer 2014 is the cause of the relatively low
total chlorophyll-a and TN in Hummock Pond. Total chlorophyll-a was the lowest at
each monitoring station in 2014 when compared to prior years. The opening protocol is
being further refined and the water quality monitoring will allow evaluation of this revised
management tool.
min max avg avg min max
System CHLA CHLA CHLA System Total Pig Total Pig Total Pig
(ug/L)(ug/L)(ug/L)(ug/L)(ug/L)(ug/L)
Miacomet Pond 0.03 19.94 4.20 Miacomet Pond 9.29 2.46 31.52
Sesachacha Pond 0.03 7.86 3.00 Sesachacha Pond 6.27 1.44 13.21
Long Pond 0.03 5.40 2.61 Long Pond 7.23 3.68 21.27
Hummock Pond 0.03 17.61 4.35 Hummock Pond 7.16 2.18 26.40
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Figure 8. Average Chlorophyll-a (CHLA) concentrations by station in the Long Pond
portion of the Madaket Harbor system during the summer 2014 sampling season
compared to 2010, 2012 and 2013.
Figure 9. Average Chlorophyll-a (CHLA) concentrations by station in the seasonally
opened Hummock Pond system during the summer 2014 sampling season compared to
2010, 2012 and 2013.
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Figure 10. Average Chlorophyll-a (CHLA) concentrations by station in the Miacomet
Pond system during the summer 2014 sampling season compared to 2010, 2012 and
2013. Miacomet Pond is not opened to the Atlantic Ocean.
Figure 11. Average Chlorophyll-a (CHLA) concentrations by station in the seasonally
opened Sesachacha Pond system during the summer 2014 sampling season compared
to 2010, 2012 and 2013.
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Average Total Nitrogen values in Hummock Pond followed the pattern in total
chlorophyll-a being lower in 2014 than prior years [2013, 2012, 2010]: 0.715 [0.900,
0.923, 0.944] mg/L, further evidence of potential improvement through flushing. In
contrast, Miacomet Pond which had no restoration activities showed similar TN levels
throughout the 4 years of monitoring: 0.982 [0.962, 0.919, 0.886] mg/L. Both of these
small estuaries only receive tidal water through periodic openings and are poorly
flushed, in contrast to Nantucket and Madaket Harbors. However, TN values appear to
be variable in both Long Pond 0.79-1.48 [0.795, 0.94,1.75] mg/L and in Sesachacha
Pond 0.922 [0.669, 0.704, 0.639] mg/L. Like Hummock and Miacomet Ponds, Long
Pond and Sesachacha Ponds are also poorly flushed. In the case of Sesachacha Pond,
the increase in TN maybe attributable to a less effective opening in 2014 compared to
previous years. However, levels remain significantly lower than during the MEP
assessment and suggest that the TMDL is being achieved or is close. Average TN
levels in all 4 ponds are significantly higher than average values in the “offshore”
stations NAN 4 and MH4 which average 0.277 [0.317, 0.344, 0.302] and 0.254 [0.278,
0.297, 0.285] mg/L, respectively (Tables 2a, 2b, 2c, Figures 1, 2).
Long Pond showed significantly lower TN levels (~40%) in 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). This variation in TN levels at station 5 is change that the
monitoring program must continue to follow closely. Station 6 continued to show a
decrease in TN from 2013 to 2014. It is necessary to determine if the increase in TN
levels at station 5 represents a real increase or merely a natural inter-annual variation.
It is unusual for one station to increase and not the adjacent station. In this case it may
be the result of poor mixing in Long Pond due to a change in tidal action through
Madaket Ditch. Although it has been observed previously, mixing even if through only
dispersion should not allow the large difference in TN levels. This should be
investigated. However, the long-term lowering of the TN levels, particularly at station 6,
appears to follow Town activities at the landfill, as both 2014 and 2013 TN levels follow
a downward trend and chlorophyll-a levels in Long Pond are significantly lower than in
2010 and generally similar to what was measured in 2013.
As in all previous years, in Sesachacha Pond, there is no noticeable nutrient or
chlorophyll gradient among any of the 4 Stations (Figure 11 and 12, Tables 2a,b,c,d)
because of the closed nature of the pond and the shape of its basin, it's mixing is more
like a freshwater lake than an estuary. However, it should be noted that TN and
chlorophyll-a concentrations in Sesachacha Pond where generally higher in 2014
compared to 2013. That there was a noticeable increase from 2013 to 2014 is good
reason to continue regular monitoring of the system (primarily to determine the
effectiveness of annual pond openings). However, TN levels remain at or below the
nitrogen threshold in the TMDL, but the recent increase is a cause for concern, as the
most likely cause relates to the success of the spring/summer opening.
Consistent with previous years monitoring results, Madaket Harbor shows a clear
nitrogen gradient (and associated metrics) from Station 1 in Hither Creek (which
receives discharge from Madaket Ditch), and is relatively poorly flushed, out to Station 2
in the Harbor with further decreases out to the off-shore Station 4. Similarly, in
Nantucket Harbor, there is a very small nutrient gradient from Wauwinet at the Head of
the Harbor and the more enclosed Polpis stations out to the entrance at Stations 8 and 4
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(Figure 6 and 12, Table 2a). There is also a chlorophyll gradient with the highest
concentrations at the 2 Polpis Stations (5 and 6), decreasing in the main Harbor and out
to the off-shore Station 4 (Table 2).
Average 2014 [2013, 2012, 2010] TN level in Madaket Harbor (Stations 1-3, not
including Station 4, offshore) was 0.390 [0.404, 0.485, 0.462] mg/L, compared to the off-
shore Station 4 0.254 [0.278, 0.297, 0.285] mg/L.
Average TN in Nantucket Harbor (all Stations except Station 4, offshore) were quite low
averaging 0.324 mg/L compared to 2010, 2012, 2013, with the offshore boundary
station 4 averaging only 0.277 mg/L in 2014 (Tables 2a, 2b). It should be noted that the
[2010] value includes station NAN-8 (the cut) whereas the 2014, 2013 and 2012 value
includes station NAN-8N which was relocated into the Town Basin within the Harbor
refer to Figure 2 for station location). That may be a reason the 2014, 2013 and 2012
average TN concentration is slightly higher for station NAN-8N than the 2010 value. TN
concentrations in the 6 streams adjacent to Nantucket Harbor in 2010 ranged from
0.565 mg/L in Stream 8 to 2.139 mg/L in Stream 6B (Table 2b). In spite of the high TN
concentrations in these 6 streams and the likely high TN loads that these streams
contribute to the Harbor, tidal flushing and dilution with lower concentration Harbor
waters seems to be an effective mechanism to keep TN levels in the main body of the
Harbor relatively low (Table 2a,b,c; Figure 2). It should be noted that the stream
stations were not sampled in 2012, 2013 or 2014, however, with increasing interest in
lowering TN concentrations in Polpis Harbor, it may be warranted to periodically sample
streams discharging to this tributary sub-embayment. TN concentrations in East Polpis
Harbor, 0.378 [0.401, 0.438, 0.484] mg/L and West Polpis Harbor 0.389 [0.385, 0.431,
0.419] , which is fed by the high TN levels in Streams 4, 6B and 6C, are somewhat
higher than the levels in the main Harbor, but still significantly lower than the levels in
the streams themselves (Table 2, Figure 2). TN levels remain above the nitrogen
threshold for these basins, although total chlorophyll-a was relatively low in 2014
reflecting the “lower TN” in that year.
Relative to the 2014, 2013, 2012 and 2010 data sets, results indicate that within Long,
Hummock and Miacomet ponds, 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 12). Based on average TN and chlorophyll-a
values in Hummock Pond, water quality appears improved over prior years, but not
enough to meet the nitrogen threshold. In Miacomet Pond, average TN values in 2014
were generally similar to 2013 (0.982 vs. 0.962) but chlorophyll-a levels appeared
slightly lower than in 2013. These are very high TN levels for this basin. However,
Miacomet Pond in 2014 likely had phytoplankton production (e.g. chlorophyll-a)
controlled by phosphorus levels, as the salinity has declined to <0.5 ppt, due to the long
time since basin was opened to the tides. At present, this pond appears to be shifting to
a freshwater ecosystem.
In reviewing the 2014, 2013, 2012 and 2010 dissolved oxygen data, it does not appear
that there is sufficient temporal sampling in any one year to capture the critical minimum
oxygen levels. Therefore, while assessment of the oxygen levels in each estuary was
performed, it will be necessary to conduct a multi-year composite analysis once
sufficient data has been collected. It is also possible to strengthen the dissolved oxygen
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data base in specific estuarine basins as each years monitoring results are assessed
through the deployment of continuously recording DO sensors. However this should
only be performed on an “as needed basis” rather than as part of the long-term
monitoring program. We have made some recommendations which we have noted at
the end of the discussion section.
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 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). Trophic health scales generally range from Oligotrophic
(healthy-low nutrient) to Mesotrophic (showing signs of deterioration of health due to
nutrient enrichment) to Eutrophic (habitats impaired and degraded, high nutrient and
organic matter). 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, 2012,
2013 and 2014) using the summer monitoring data. The Index scores were calculated
in 2 ways, one which included the low dissolved oxygen for each year in the index ("with
DO", Table 7) and one which excluded the oxygen metric ("without DO", Table 8). 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. 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.
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 difference between the "with DO" and "without DO" Index scores based on
the 2013 and 2014 data, although the analysis is presented for informational purposes
herein (Tables 7a and 8a). It should be noted that if there is a bias 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). Given that
inclusion oxygen did not generally change the bay health rank, although it did yield a
change in the numerical value, the standard Index was used for assessment.
The Health Status of each site was based on the Index Score, which is 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 10-14 show
the distribution of Health Status throughout each estuary based on each of the 4 years
of monitoring (2010, 2012, 2013, 2014). Numerical results are color coded for ease of
mapping. The colors of each triangle represent the Bay Health Index status of its site
and follow the designation scheme below:
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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 between all 4 years of monitoring, although some improvement was
observed. 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). However, 2 systems do
appear to show a potential shift in nitrogen related health over the past 4 years, Hither
Creek and lower Hummock Pond (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 is supporting 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 nitrogen impairment problems. Over the 4 years of monitoring
Hither Creek (Station 1) has consistently supported the poorest “health” status within the
Madaket Estuary (Table 7, 8, Figure 16). Hither Creek is clearly nitrogen enriched and
showing continuing impairment based on a variety of parameters. However, over the
past 4 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 –high
water quality in 2014. The main basin of Madaket Harbor is showing relatively high
water quality in each year with only a slight gradient on the ebbing tide from offshore of
Hither Creek out to the Harbor entrance. The gradient was most significant in 2012 and
2013. It appears that Station 2, near the outlet to Hither Creek is receiving low quality
waters on the ebb tide from Hither Creek and that this is controlling water quality at this
nearshore location. The inter-annual difference at this site likely stems from the degree
that the poor water quality plume from Hither Creek was captured each year, than a shift
in status. In contrast, the offshore sites (3 & 4) support high quality waters resulting
from low nitrogen inputs and very high rates of water exchange. The 4 year upward
trend in health index is possibly related to the reduced loading from the landfill to upper
Long Pond and an improvement in the ebbing waters through Madaket Ditch. This trend
needs to be reconciled with the variability observed at Station 5 and 6 in Long Pond and
the mechanism for the large difference between the stations in 2014. If the improvement
in Hither Creek continues it will meet the predictions of the MEP, and may offset the
need for a fraction of the watershed sewering.
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
16). Unlike Madaket Harbor which is marine, Long Pond is a brackish water system
resulting from groundwater inflows and its restricted tidal exchange. Long Pond’s Bay
20
Health scores for both stations (5 & 6) in the 4 years of monitoring (2010, 2012, 2013,
2014) clearly indicate poor nutrient related water quality. It is nearly certain that this
poor water quality water flowing into the head of Hither Creek during the ebb tide
represents a localized input that contributes to creating the low water quality observed in
Hither Creek as well. While there may be some small decline in nitrogen levels in the
upper basin (Station 6) the level is still very high and results in poor clarity, algal blooms
and nutrient related stress to aquatic resources. The lack of 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 show improving water quality at stations 5 and 6 in 2012, 2013 and 2014
compared to 2010 and in the MEP threshold analysis (see analysis and figures above).
The issue is that presently there has not been a large enough shift to bring metrics
above Health Index thresholds to change the rating significantly.
Nantucket Harbor
Nantucket Harbor is presently supporting the highest water quality of Nantucket's
estuaries. The main basin is supporting high quality waters, with only a periodic small
level of decline in uppermost basin of the main Harbor, Wauwinet basin (Figure 17).
Wauwinet basin had the highest average total nitrogen values for the Harbor System in
2013 (0.415) consistent with its designation as the sentinel station for the main basin. In
contrast the 2014 results show the main basin to be of high water quality throughout,
consistent with the chlorophyll-a and TN levels in 2014 versus prior years. However, the
enclosed sub-basin of Polpis Harbor (East and West) is showing moderate impairment
and only moderate water quality. This designation stems both from both elevated
nitrogen levels and consequent enhancement of phytoplankton, with summer averages
of 10-15 ug/L typical. However, in 2014 Polpis Harbor, like the main basin, showed
high water quality, but it is unlikely that this will be sustained, instead it may indicate a
slight improvement that will show variation over time. While the Harbor is generally
supporting high quality waters, the variability in the index in Wauwinet and Polpis should
be monitored to ascertain the long-term health of these basins and that efforts to restore
these basins by the Town continue to move forward to meet the MassDEP TMDL for
this system. Overall, Nantucket Harbor appears to be relatively stable from year to year
and even with high index scores the higher level metrics support the contention that it is
still above its TMDL threshold, as also for Polpis Harbor.
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 as
part of the pond management strategy to enhance flushing of the pond and improve
water quality to reach the threshold. 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
21
chlorophyll-a. The monitoring data suggest that the pond may still be reaching a new
balance, as the limited 3 years of data (2010, 2012 and 2013) show virtually the same
TN concentrations in each year. In contrast the 2014 results showed a higher level of
TN, ~0.9 mg/L, which may relate to the quality of the pre-summer opening. Given the
prior 3 years, 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. Using the
Index alone, changes in water quality in Sesachacha Pond over the past 4 years have
been stable at a moderate level of estuarine health (Figure 18). Additional higher level
assessment of Sesachacha Pond initiated by the 2010 monitoring results is being written
to document the level of improvement in nutrient related health of this system and the
degree to which the pond meets conditions for habitat restoration documented in the
2006 MEP nitrogen threshold analysis for Sesachacha Pond. It appears that like other
periodically opened pond, the quality of the opening (amount of water exchanged)
controls the level of water quality in the following months.
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 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). There is a small gradient in water quality with moderate
to poor conditions near the ocean and poor conditions in the uppermost basins (Figure
19). This gradient stems from the periodic openings and over-wash events. The
uppermost basin, Station 7, is approaching fresh/brackish conditions and is currently
supporting mainly freshwater plant and animal habitats. This basin is particularly
eutrophic with phytoplankton blooms exceeding 70 ug/L (offshore waters are ~2 ug/L).
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. 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). All of the metrics are consistent with a nutrient impaired basin in both
2010 and 2012. 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.
Given previous studies of Hummock Pond it appeared that its nutrient related health was
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 appear to support that tidal flushing was
22
improved as nutrient related health was highest in 2014 of the years monitored. This
opening program and associated monitoring around the openings and in the summer
should be continued to set metrics for a “successful” opening and document and further
refine the opening protocol for the Town’s on-going program.
Miacomet Pond
Miacomet Pond is a closed coastal salt pond that is seldom (once in the past ten years)
opened to the ocean to flush out nutrients and organic matter on the ebb tide and
receive saline waters on the flood tide. As a result of the lack of tidal flow and
groundwater inputs the pond is presently freshwater, with salinity levels in each of the 4
years of monitoring of <0.6 ppt. The present non-tidal state and 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 conditions the present norm
(Figure 20). 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) several times the levels
found in the high quality basins of Nantucket and Madaket Harbors. All of the metrics
are consistent with a nutrient impaired basin. However, if the freshening of this basin
continues, it may come into a new equilibrium as a purely 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). At some point it may
be useful 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 presently
controlling pond health.
It will be difficult for Miacomet Pond to maintain itself as a purely freshwater system as
storm overwash and rising sea level will tend to periodically cause seawater intrusion
into its lower basin. An analysis of future conditions for Miacomet Pond as sea level
rises may be in order in the near future, as remediation is considered.
Recommendations for Future Monitoring
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, Madaket Harbor
(stations 1&2) and Wauwinet basin in Nantucket Harbor should be considered for this
analysis at some time in the future. However, procedural steps should also be
implemented to strengthen the oxygen data base from the on-going monitoring program.
Approaches to address these 2 issues are:
1) 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.
2) Long Pond is approaching the time when a detailed analysis of nitrogen
entering from the land fill should be conducted, particularly how the land fill
remediation is projected to improve water quality in the adjacent estuary. The
monitoring results from 2012 and 2013 appear to show a significant reduction
23
in TN over historical conditions and 2010. The TN pattern in 2014 suggests
that there may be a restriction to mixing between station 5 and 6 which should
be investigated and if possible managed.
Additionally, it should be noted that the stream stations discharging to Nantucket Harbor
(specifically Polpis Harbor) were not sampled in 2012, 2013 or 2014. However, with increasing
interest in lowering TN concentrations in Polpis Harbor to meet the MEP established TN
threshold, it may be warranted to resume sampling in streams discharging to this tributary sub-
embayment to gage the degree to which the loads these streams contribute affect the TN
concentration at the sentinel station in Polpis Harbor.
Nitrogen and Phosphorus budgets should be developed for Miacomet Pond and a quantitative
analysis of N versus P as the driving nutrient of eutrophication. This information will support
management actions for managing the pond in its variable salinity state.
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 to refine the opening protocol and gauge its effectiveness. This
protocol still needs to be codified and further refined. This can only be done by
monitoring several openings to relate opening metrics to subsequent water quality.
Management should focus on how to create the most efficient openings, and evaluate
the need for a mid-summer opening in this system. The new opening program and
associated monitoring around the openings and in the summer should be continued to
set metrics for a “successful” opening and document and further refine the opening
protocol for the Town’s on-going program.
24
Table 2a. 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
25
Table 2b. 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
26
Table 2c. 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).
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
27
Table 2d. 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).
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
28
Figure 12. Comparison of nitrogen species (mg/L) in Nantucket Harbor in summers, 2010 (upper left); 2012 (upper right); 2013 (btm left);
2014 (btm right). Total nitrogen is the sum of the inorganic and organic fractions (top line in each graph). All figures are to same scale.
29
Figure 12 cont'd. Comparison of nitrogen species (mg/L) in Hummock Pond in summers, 2010 (upper left); 2012 (upper right); 2013 (btm
left); 2014 (btm right). Total nitrogen is the sum of the inorganic and organic fractions (top line in each graph). All figures are to same scale.
30
Figure 12 cont'd. Comparison of nitrogen species (mg/L) in Sesachacha Pond in summers, 2010 (upper left); 2012 (upper right); 2013 (btm
left); 2014 (btm right). Total nitrogen is the sum of the inorganic and organic fractions (top line in each graph).
31
Figure 12 cont'd. Comparison of nitrogen species (mg/L) in Madaket Harbor in summers, 2010 (upper left); 2012 (upper right); 2013 (btm
left); 2014 (btm right). Total nitrogen is the sum of the inorganic and organic fractions (top line in each graph). All figures are to same scale.
32
Figure 12 cont'd. Comparison of nitrogen species (mg/L) in Long Pond (Madaket Harbor System) in summers, 2010 (upper left); 2012
(upper right); 2013 (btm left); 2014 (btm right). Total nitrogen is the sum of the inorganic and organic fractions (top line in each graph). All
figures are to same scale.
33
Figure 12 cont'd. Comparison of nitrogen species (mg/L) in Miacomet in summers, 2010 (upper left); 2012 (upper right); 2013 (btm left);
2014 (btm right). Total nitrogen is the sum of the inorganic and organic fractions (top line in each graph). All figures are to same scale.
34
Figure 13. 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 and 2012.
35
Table 3. 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 and 2014.
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.
Sub-Embayment
Monitoring
Station
Historical
MEP
Mean TN
(mg/L) s.d.
2010
Town
ID
2010
Mean TN
(mg/L)
2012
Mean TN
(mg/L)
2013
Mean TN
(mg/L)
2014
Mean TN
(mg/L)
Head of the Harbor - Upper 2 0.408 0.188 NA NS NS NS
Head of the Harbor - Mid Town 3 0.401 0.115 3 0.392 0.411 0.415
0.345
Head of the Harbor -
Lower 2A 0.339 0.070
NA NS NS NS
NS
Pocomo Head 3 0.335 0.081 NA NS NS NS NS
Quaise Basin 3A+Town 2 0.336 0.112 2 0.297 0.364 0.345 0.314
East Polpis Harbor 4+Town 6 0.362 0.105 6 0.438 0.484 0.401 0.378
West Polpis Harbor 4A+Town 5 0.388 0.119 5 0.431 0.419 0.385 0.389
Abrams Point 5 0.335 0.060 NA NS NS NS NS
Monomoy 6 0.297 0.086 NA 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
Nantucket Sound OS+Town 4 0.239 0.041 4 0.283 0.3441 0.3171 0.277
36
Figure 14. 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.
Sampling Station
Location
Historical
MEP
Mean TN
(mg/L)
s.d.
2010
Mean TN
(mg/L)
2012
Mean TN
(mg/L)
2013
Mean TN
(mg/L)
2014
Mean TN
(mg/L)
Sesachacha Pond 1.197 0.078 0.684 (0.704) 0.678 (0.639) 0.714 (0.669) 0.919 (0.922)
Table 4. 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 and 2014 represent the
average at Station 1, with the average of stations 1-4 in ( ).
37
Figure 15. Estuarine water quality monitoring station locations in the Madaket Harbor and Long
Pond Systems.
38
Table 5. 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 and
2014 by the Town of Nantucket Marine and Coastal Resources Department.
Hummock Pond
and
Miacomet Pond
Station ID's
2014 2013 2012 2010 2005/2007
TN
(mg/L)
TN
(mg/L)
TN
(mg/L)
TN
(mg/L)
TN
(mg/L)
Mean Mean Mean Mean Mean S.D.
HUM1 0.651 0.769 0.666 0.616 0.751** 0.374
HUM3 0.643 0.827 0.863 0.589 0.630** 0.388
HUM5 0.653 0.881 0.871 0.766 ND ND
HUM7 0.873 1.170 1.301 1.786 1.283** 0.969
HUM8 0.755 1.064 0.944 0.983 ND ND
MP1 0.864 0.792 0.828 0.854 0.842* 0.191
MP2 0.784 1.036 0.880 0.811 0.855* 0.213
MP3 1.297 1.058 0.950 1.093 0.280* 0
*2005 data only
**2007 data only
Table 6. 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 and 2014. All values are mg/L.
Sub-Embayment
Monitoring
Station
Historical
MEP Mean
TN
(mg/L) s.d.
2010
Mean TN
(mg/L)
2012
Mean TN
(mg/L)
2013
Mean TN
(mg/L)
2014
Mean TN
(mg/L)
Madaket Harbor MEP M1 0.336 0.098
Madaket Harbor Town 4 0.285 0.297 0.278 0.254
Madaket Harbor MEP M2 0.395 0.083
Madaket Harbor Town 2 0.436 0.444 0.323 0.347
Madaket Harbor MEP M3 0.415 0.090
Madaket Harbor Town 3 0.324 .356 0.314 0.376
Hither Creek MEP M4 0.581 0.193
Hither Creek MEP M5 0.780 0.178
Madaket Harbor MEP M6 0.347 0.067
Madaket Harbor MEP M10 0.422 0.127
Hither Creek
MEP
M11+Town 1 0.620 0.215 0.626
0.655
0.573
0.445
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
Long Pond MEP LOPO3 0.924 0.234
Long Pond
MEP
LOPO4+Town 6 0.894 0.278 2.044
0.867
0.880
0.788
North Head Long P. MEP LOPO5 0.954 0.271
39
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
Table 7. 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).
40
Table 7a. 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
41
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
Table 7b. 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).
42
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 7c. 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).
43
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
Table 8. 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).
44
Table 8a. 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
45
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
Table 8b. 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).
46
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 8c. 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).
47
Figure 16. Madaket Harbor Eutrophication Index 2010 (top triangle) and 2014 (bottom triangle). Index was calculated with dissolved oxygen.
Colors indicate High (Blue), Moderate (Yellow), Fair/Poor (Red) nutrient related water quality.
48
Figure 17. Nantucket Harbor Eutrophication Index 2010 (top triangle) and 2014 (bottom triangle). Index was calculated with dissolved
oxygen. Colors indicate High (Blue), Moderate (Yellow), Fair/Poor (Red) nutrient related water quality.
49
Figure 18. Sesachacha Pond Eutrophication Index 2010 (top triangle) and 2014 (bottom triangle).
Index was calculated with dissolved oxygen. Colors indicate High (Blue), Moderate (Yellow), Fair/Poor
(Red) nutrient related water quality.
50
Figure 19. Hummock Pond Eutrophication Index 2010 (top triangle) and 2014 (bottom triangle). Index
was calculated with dissolved oxygen. Colors indicate High (Blue), Moderate (Yellow), Fair/Poor (Red)
nutrient related water quality.
51
Figure 20. Miacomet Pond Eutrophication Index 2010 (top triangle) and 2014 (bottom triangle). Index
was calculated with dissolved oxygen. Colors indicate High (Blue), Moderate (Yellow), Fair/Poor (Red)
nutrient related water quality.