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Technical Memorandum
FINAL
Water Quality Monitoring and Assessment of the
Nantucket Island-Wide Estuaries and Salt Ponds
Update 2015
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
January 7, 2016
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The Technical Memorandum on the 2015 Nantucket Water Quality Monitoring Program is
organized consistent with previous SMAST water quality monitoring summaries (2010, 2012,
2013, and 2014) for direct comparison to data from the previous years of monitoring. However,
the 2015 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 it is included
by reference.. The 2015 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 Sites
2. Trophic State: Water Quality/Eutrophication Status
3. Recommendations for Future Monitoring
As in previous years, the 2015 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, 2012-2014), the approach utilized for the
collection and analysis of 2015 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 with the Nantucket Natural Resources Department who’s primary
focus was 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:
1. determine the present (2015) ecological health of each of the main salt ponds and
estuaries within the Town of Nantucket,
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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
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, 2013, and 2014 sampling efforts, 2015 sampling 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 (2015), Table 1b (2014), Table 1c (2013), Table 1d
(2012), and Table 1e (2010). Samples collected in 2015 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 is presented in
tabular form in Appendix A in Annual Technical Memoranda (2012, 2013) and are not
being reproduced again herein.
The physical parameters measured in the estuaries during the 2015 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 pheophytin-a and orthophosphate. Similar to the summer of
2014, the water quality monitoring undertaken in 2015 was focused mostly on estuarine
stations with an additional 3 stream locations. In 2015, 32 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, 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 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 2015
appears to have sustained high water quality for most Nantucket Harbor stations though
some did show a possible slight decrease in water quality. Hummock Pond water quality
in the summer of 2015 showed improvement, most likely due to newly implemented
opening protocol resulting in significantly more effective openings and continuing trend
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toward improved conditions in Long Pond and decline in Miacomet Pond seen in the
chlorophyll a pigments, nitrogen and eutrophication index (see below). This analysis
revealed that the significant improvement in Sesachacha Pond seen previously has
diminished and the Pond has declined in nitrogen related water quality over the past 2
years (2014, 2015) possibly due to the inlet openings. If so, this recent decline should be
readily reversible.
Table 1a. Sampling Schedule for 2015 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
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
5
Table 1b. Sampling Schedule for 2014 Nantucket Water Quality Monitoring Program
Note: * The September 15 sampling of Nantucket Harbor only involved one station (NAN-4).
Table 1c. 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 1d. Sampling Schedule for 2012 Nantucket Water Quality Monitoring Program
Table 1e. 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, 2014, and 2015.
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Figure 2. Nantucket Harbor sampling stations 2015. Station NAN-8 (the cut) was only sampled in 2010 and location changed in 2011 -
2015. 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, 2015.
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Figure 4. Hummock Pond sampling stations 2010, 2012, 2013, 2014, 2015. 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, 2014, and 2015.
Station 3
Station 1
Station 2
Station 3
Station 1
Station 2
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Figure 6. Polpis Harbor Stream Sampling locations (ST-3,4,6B) 2015. Water samples from mid
depth in water exiting culverts.
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Figure 7a. Oyster Aquaculture Sampling locations Nantucket Harbor (ORS-2,3,4,5,6) and Madaket
Harbor (ORS-1) 2015. Sites are associated with possible oyster aquaculture areas.
Figure 7b. Oyster Aquaculture Sampling location Madaket Harbor (ORS-1) 2015. Site is associated
with possible oyster aquaculture areas.
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Summary of 2015 Water Quality Results for Nantucket Sampling
While there were some localized areas of interest (Hummock Pond {+}, Miacomet Pond
{-}, Long Pond {+}1, see below), the overall trends in water quality observed in 2015
follow and expand the pattern observed in 2010, 2012, 2013, 2014. Water samples
collected from May through September in the estuarine systems indicate that organic
nitrogen (dissolved + particulate) still dominates the Total Nitrogen pool (96% in 2015
alone), while bio-available nutrients in the form of nitrite and nitrate (NOx) and
ammonium (NH4) account for only 4% of Total Nitrogen pool in 2015 (Table 2a,b,c,d,e
Figure 14). 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 2015 (Table 2a), as noted in
prior years as well (Table 2b,c,d,e). 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,e, Figure 8,9). The level of variation is common and
underscores the need for multi-year monitoring to establish trends.
Figure 8. Average Chlorophyll-a (CHLA) concentrations by station in the well flushed
Nantucket Harbor system during the summer 2015 sampling season. Stations Nan-5
1 {+} indicates improved conditions in 2015; {-} indicates declining conditions in 2015.
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and 6 are in Polpis Harbor the rest relate to the main basin. Note that 2015 levels were
about average within the upper basins and relatively constant throughout the Harbor at a
level consistent with low-moderate nitrogen enrichment.
Figure 9. Average Chlorophyll-a (CHLA) concentrations by station in the well flushed
Madaket Harbor system during the summer 2015 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 but 2015 total pigment levels were
slightly higher than in 2014, similar to the lower reaches of Nantucket Harbor.
While Nantucket Harbor and Madaket Harbor are both well flushed basins, they tended
to have slightly higher phytoplankton biomass (chlorophyll-a) in 2015 compared to 2014.
This was most striking in Nantucket Harbor where average chlorophyll-a at station 3 was
high compared to prior years. In Madaket Harbor the levels were also higher than all
years but 2010. This is consistent with the lower water clarity observed in 2015
(Nantucket Harbor station 3 secchi depth 2014 = 3.1 m, 2015 = 1.45 m, Madaket Harbor
MH-2 secchi 2.5 meters in 2014, 2.2 in 2015) 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 higher TN levels with higher
chlorophyll-a levels (see below). This is particularly apparent in Nantucket Harbor
(station 3) and provides additional evidence that nitrogen is the eutrophying nutrient in
these systems.
Where tidal flushing is more restricted in Long, Hummock, Miacomet and Sesachacha
Ponds, the moderate levels of water clarity were consistent with the chlorophyll-a
concentrations that have a higher (2x-3x) average (compared to Nantucket and Madaket
Harbors), 5.7 ug/L (max. 11.37 ug/L), 4.6 ug/L (max. 16.6 ug/L), 37.96 ug/L (max. 158.6
ug/L) and 6.74 ug/L (max. 10.74 ug/L), respectively (Table 2a, Figures 10, 11,12,13).
These general patterns were also observed in the monitoring results of the prior year
(2014, 2.6 ug/L, 4.4 ug/L, 4.2 ug/L and 3.0 ug/L). However, it should be noted that the
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chlorophyll-a levels in Long Pond, Hummock Pond, Miacomet Pond and Sesachacha
Pond all appear to be higher when compared to 2014 average values. In Sesachacha
Pond chlorophyll-a levels have risen slightly in 2015 compared to 2014 (maybe due to a
less effective opening compared to the prior years of 2012, 2013 and 2014).
Additionally, total pigment values (chlorophyll-a + pheophytin) were significantly higher in
Miacomet Pond in 2015 compared to 2014 (45.9 ug/L vs. 11.1 ug/L). While generally all
the sampling dates for Miacomet Pond showed elevated levels for total pigment in 2015,
consistent with other estuaries, one date had exceptionally high values at all stations
indicating that sampling likely occurred during a strong bloom event. 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 compared
to historic levels and 2010 but do show variation (e.g. all ponds higher in 2015 compared
to 2014). However, Sesachacha Pond showed much improved water quality compared
to its long term 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. It appears that
Sesachacha Pond quality is tightly linked to the success of its periodic openings, which
significantly improved conditions in 2012 and 2013, but has recently showed declines in
2014 and 2015. This was clearly seen in 2014 as well as 2015 though in 2015 TN levels
appeared higher than in 2014 with an associated increase in total pigment levels
(potentially related to a less effective opening in 2015 compared to 2014). The
temporal data indicate that Sesachacha Pond can be significantly restored by improved
pond openings and that recent openings need to be re-examined relative to the recent
increase in nitrogen enrichment and associated water quality metrics (chlorophyll,
dissolved oxygen).
After a significant drop in chlorophyll-a in 2013 (versus 2010, 2012) Long Pond has
maintained its phytoplankton levels at a high/moderate level 2013-2015. This decline
was noted previously and is possibly a result of activities at the landfill leading to
declining nitrogen inputs. However, Long Pond continues to be eutrophic and impaired.
In contrast, Miacomet Pond which is not open to tidal flows and has become very fresh
(avg. salinity 0.10 ppt), showed a large increase in chlorophyll-a levels in 2015 and
showed the highest levels since the monitoring program began and the highest of all
Nantucket’s estuaries. Miacomet Pond is clearly supporting eutrophic conditions for
both fresh and salt water (>35 ug/L total pigment). Moreover the phytoplankton bloom
was pond-wide and persisted throughout the sampling period.
Hummock Pond showed significantly lower total chlorophyll-a levels in summer 2015
than prior years (2010,2012,2013) although slightly higher compared to 2014. The
2014 results were the lowest levels measured over the 2010-2015 monitoring period and
while 2015 was slightly higher than 2014, chlorophyll levels in 2015 were still moderate-
high as a metric of eutrophication. While two years (2014 and 2015) only represent the
beginning of a restoration trend, the lower levels in those two years is consistent with an
improved opening protocol developed in 2014 for the Hummock Pond openings. The
Town and the 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
followed by a more effective opening in October 2014 which lowered TN levels in the
pond and raised its salinity. It is possible that the combination of the good opening and
the meteorological conditions that appear to have supported higher water quality in most
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of the estuaries in summer 2014 was the cause of the relatively low total chlorophyll-a
and TN in Hummock Pond in 2014. Total chlorophyll-a was the lowest at each
monitoring station in 2014 when compared to prior years. In April 2015, Hummock Pond
was opened and water levels and water quality were monitored before and after the
opening. The April 2015 opening did appear to be a more effective opening compared
to the October 2014 opening thereby contributing to the enhanced water quality
observed during the summer 2015. Average TN levels in the summer of 2015 were
moderately lower than in summer 2014 (0.583 mg/L and 0.715 mg/L respectively)
though average total pigment in 2015 was slightly higher than in 2014 (9.68 ug/L and
7.08 ug/L respectively). It is possible that the slightly higher total pigment values
observed in 2015 despite slightly lower TN values is the result of the warmer conditions
experienced during the summer of 2015. Also, it is clear that the pond has not reached
equilibrium with its new hydrodynamic conditions, such that further improvements are
anticipated if the new opening protocol is continued. The opening protocol will be further
refined as more data is gathered from future openings and the water quality monitoring
will allow evaluation of this revised management tool.
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
Figure 10. Average Chlorophyll-a (CHLA) concentrations by station in the Long Pond
portion of the Madaket Harbor system during the summer 2015 sampling season
compared to 2010, 2012, 2013, and 2014.
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Figure 11. Average Chlorophyll-a (CHLA) concentrations by station in the seasonally
opened Hummock Pond system during the summer 2015 sampling season compared to
2010, 2012, 2013, and 2014.
Figure 12. Average Chlorophyll-a (CHLA) concentrations by station in the Miacomet
Pond system during the summer 2014 sampling season compared to 2010, 2012, 2013,
and 2014 Miacomet Pond is not opened to the Atlantic Ocean.
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Figure 13. Average Chlorophyll-a (CHLA) concentrations by station in the seasonally
opened Sesachacha Pond system during the summer 2015 sampling season compared
to 2010, 2012, 2013, and 2014.
Average Total Nitrogen values in Hummock Pond were lower in 2015 even though total
pigment appeared slightly higher than in 2014. Total nitrogen averaged 0.583 mg/L in
2015 whereas in prior years [2014, 2013, 2012, 2010] average TN values where [0.715,
0.900, 0.923, 0.944] mg/L respectively. This temporal trend is consistent with the timing
of improved flushing observed in 2014 and 2015 openings, as is the decline from 2014
to 2015 which is expected from a system in transition. In contrast, Miacomet Pond
which had no restoration activities or openings showed higher TN levels in 2015
compared to the previous 4 years of monitoring: 1.202 mg/L compared to [0.982, 0.962,
0.919, 0.886] mg/L respectively. These high levels of TN are consistent with small
estuaries that only receive tidal water through periodic openings (Hummock Pond) or
overwash during storm events (Miacomet Pond) and are poorly flushed. The effect of
flushing is clearly seen by comparing TN and pigment levels in Nantucket’s well flushed
estuaries (Nantucket and Madaket Harbors) to these “closed” poorly flushed estuaries.
Total Nitrogen values appear to be temporally variable in both Long Pond 0.656-0.697
[1.14, 0.795, 0.94,1.75] mg/L and in Sesachacha Pond 0.904 [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 TN levels also appear to
be related to the success of the periodic openings. The similar TN levels in 2015 as
compared to 2014 likely relate to similar opening characteristics and are higher than the
prior 2 years which had better openings. It is worth noting that the high historic levels
and 2010 levels were under less robust opening conditions, prior to the Town’s new
awareness of the importance openings as a pond management tool. It should be noted
that TN levels in 2015 (and 2014) remain significantly lower than during the MEP
assessment and suggest that achieving the TMDL may be possible by refined openings,
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saving infrastructure costs. Average TN levels in all 4 ponds are significantly higher
than average values in the “offshore” stations NAN 4 and MH4 which average 0.297
[0.277, 0.317, 0.344, 0.302] and 0.328 [0.254, 0.278, 0.297, 0.285] mg/L, respectively
(Tables 2a, 2b, 2c, 2d, 2e, 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 is possible that sample
data for that one sampling date is aberrant, which is supported by statistical analysis of
the complete data set (2010-2015).
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). TN concentrations at station 5 declined again in 2015 to
0.656 mg/L from 1.48 mg/L in 2014. This variation in TN levels at station 5 needs to be
tracked closely by the monitoring program, as MEP modeling suggests that conditions
will improve as the landfill process continues. Station 6 continued to show a decrease in
TN concentrations. Station 6 TN concentrations in 2015 dropped to 0.697 mg/L from
0.788 mg/L in 2014. Based on the lower TN concentrations observed in 2015, it is
possible that the increase in TN levels at station 5 from 2013 to 2014 represented a
natural inter-annual variation. While it is unusual for one station to increase and not the
adjacent station, in this case it may be the result of poor horizontal mixing in Long Pond
due to a changes 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. Continued monitoring of station 5 is warranted. The long-term lowering of
the TN levels, particularly at station 6, appears to follow Town activities at the landfill, as
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 and 2014. The monitoring program will be assessing potential
causes of the large temporal variations in the lower basin of Long Pond (Station 5).
As in all previous years, in Sesachacha Pond, there is no noticeable nutrient or
chlorophyll gradient among any of the 4 Stations (Figure 13 and 14, Tables 2a,b,c,d,e)
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 while TN and
chlorophyll-a concentrations in Sesachacha Pond where generally higher in 2014
compared to 2013, TN levels in 2015 remained high and very similar to 2014 (0.904
mg/L and 0.922 mg/L respectively). Total pigment in 2015 was higher than what was
observed in 2014 (11.07 ug/L and 6.37 ug/L respectively), however, the higher pigment
levels in 2015 were generally observed across all the estuaries of Nantucket indicating
the higher levels likely meteorologically related. It should be noted that the average
temperature May-September 2015 (22.6 degrees Celsius) was highest when compared
to 2010-2014 (22.5, 19.8, 22.3, 19.6, 19.3 degrees Celsius respectively). That there was
a noticeable increase from 2013 to 2014 and consistency between 2014 and 2015 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 are now
above the nitrogen threshold in the TMDL, and the 2014 and 2015 increase is a cause
for concern, particularly after a few years of much lower TN levels (~0.6 mg/L).
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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 Long Pond via Madaket Ditch), and is relatively poorly flushed,
out to Station 2 in the Harbor, with further decreases out to the off-shore Station 4
(Figure 9 and 14, Table 2a). 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. There is also a chlorophyll
gradient with the highest concentrations at the 2 Polpis Stations (5 and 6) and Wauwinet
basin, decreasing in the main Harbor and out to the off-shore Station 4.
Average 2015 [2014, 2013, 2012, 2010] TN level in Madaket Harbor (Stations 1-3, not
including Station 4, offshore) was 0.422 [0.390, 0.404, 0.485, 0.462] mg/L, compared to
the off-shore Station 4 0.328 [0.254, 0.278, 0.297, 0.285] mg/L. As mentioned above,
the best estimate of the offshore TN concentration for station MH4 is 0.295 mg/L.
Average TN in Nantucket Harbor (all Stations except Station 4, offshore) were quite low
averaging 0.381 mg/L compared to 2010, 2012, 2013, 2014, with the offshore boundary
station 4 averaging only 0.297 mg/L in 2015 (Tables 2a, 2b). It should be noted that the
2010 value includes station NAN-8 (the cut) whereas the 2015, 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). 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 2e). In spite of the high TN concentrations in these 6 streams
and the 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,d; Figure 2). A subset
of streams sampled in 2010 where sampled again in 2015 and the results are discussed
below. 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 was warranted to periodically sample streams discharging to this tributary sub-
embayment. TN concentrations in East Polpis Harbor, 0.404 [0.378, 0.401, 0.438,
0.484] mg/L and West Polpis Harbor 0.422 [0.389, 0.385, 0.431, 0.419] , which are 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). It should be noted that these two stations in Polpis Harbor (NAN-5
{Polpis west} and NAN-6 {Polpis east}) do show an increased TN concentration
compared to levels observed in 2014. TN levels remain above the nitrogen threshold for
these basins, although total chlorophyll-a was still relatively low in 2015. Total pigment
at Stations NAN-5 and NAN-6 were slightly higher in 2015 compared to 2014 reflecting
the slightly higher TN in that year and warm summer conditions in 2015. Overall, TN
concentrations in Nantucket Harbor were slightly higher in 2015 (0.381 mg/L) compared
to summer 2014 (0.324 mg/L). As such it is important to continue summer water quality
monitoring and watershed based nutrient management. However a full evaluation of the
streams would be to add stream volumetric flow to the stream sampling such that
nitrogen load to the harbor could be monitored, as load is associated with the harbor TN
levels.
Relative to the 2015, 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
22
and poorly flushed reaches of the estuaries to lower concentrations closer to the outlets
where flushing is more effective (Figure 14), although the gradient appears to be a bit
flatter in 2015 for both Hummock Pond and Long Pond. Based on average TN values in
Hummock Pond, water quality in 2015 appears improved over prior years, but not
enough to meet the nitrogen threshold needed for restoration. In Miacomet Pond, while
average TN values in 2014 were generally similar to 2013 (0.982 mg/L vs. 0.962 mg/L),
TN values in 2015 were even higher (1.202 mg/L) and chlorophyll-a levels were also
significantly higher than in 2014 and 2013. These are very high TN levels for this basin.
However, Miacomet Pond in 2015 as in 2014 likely had phytoplankton production (e.g.
chlorophyll-a) also controlled by phosphorus levels, as the salinity has declined to ~0.1
ppt, due to the extended time since this basin was opened to the tides. As TP and PO4
samples were collected in parallel with the nitrogen fractions in the 2015 surveys of
Miacomet Pond, it was possible to assess nitrogen versus phosphorus significant to
eutrophication from the N to P ratios as well as Carbon to Nitrogen (C/N) ratios. These
field ratios are compared to the idealized Redfield 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,
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 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 N/P ratios lower at the head and increasing to the middle
and lower portions (MP3 - MP1 - MP2, N/P ratio 16.9, 36.9, 34.4 respectively, Redfield
N/P ratio is 16). Ratios significantly greater than 16 indicate that phosphorus additions
likely result in increased eutrophication and that Phosphorus should be a focus of pond
management. This is the case in the middle and lower pond. The upper pond appears
to be sensitive to both nitrogen and phosphorus, such that overall both nutrient need to
be monitored and considered for management of Miacomet Pond.
More specifically, use of Redfield ratio information in freshwater is greatly enhanced when
nutrient ratios are examined together with controlled biotests (bottle tests, mesocosms) with
different levels of P and N amendments to natural phytoplankton community. These types of
biotests were employed by the Coastal Systems Program for an assessment of Oyster Pond in
Falmouth specifically to better determine the degree of N or P limitation in that coastal salt
pond for nutrient management purposes. Comparison of algal biotest results and chemical
nutrient concentrations in lakes has suggested that a mass N:P ratio above 17-20 indicates P
limitation, a ratio below 10 indicates N limitation and values between 10 and 17 indicate that
either of the nutrients may be limiting." (Petri Ekholm, Finnish Environment Institute, 2008).
That there is a clear difference between the N/P ratios in the upper part of the pond versus the
lower part of the pond and considering the N/P ratio at the uppermost station is ~16 and the
lower station is significantly >16 (see table below) suggests that the upper portion of Miacomet
could be either N limited or P limited while the middle and lower portions of the system are
likely P limited. 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 appears to be shifting 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.
23
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
Unlike previous sampling years (2012, 2013, 2014), stream sampling and flow
measurement was added to the 2015 monitoring program in Nantucket Harbor,
particularly due to the interest in achieving the MEP TN threshold in Polpis Harbor
(NAN-6 is considered the MEP sentinel station and with a TN threshold concentration of
0.355 mg/L for restoration). Samples collected from 3 stream stations (ST3, ST4,
ST6B) discharging to Polpis Harbor showed high TN concentrations (1.218, 1.060, 1.10
mg/L respectively, based on data presented in Table 2). It should be noted that the
average TN concentration for station ST3 is 1.038 mg/L if the 8/31/2015 sampling date
(TN concentration = 0.499 mg/L) is included in the calculation. It is possible that sample
data for that one sampling date is abnormally low compared to the results from the three
other sampling dates at that station (0.939-1.554 mg/L). As such, the 8/31/2015 sample
result was not utilized to calculate summer average TN concentration for station 3.
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 are consistent with the high concentrations observed in 2015 and as
such, warrants continued monitoring of stream nutrient concentrations and stream flow
discharging to Polpis Harbor specifically. Management of these flows and nutrient loads
may help to achieve the MEP TN threshold for Polpis Harbor at the sentinel station
(NAN-6).
In addition to nutrient sampling, the Town of Nantucket staff measured the velocity of
water flowing at each sampling location at the time water quality samples were being
collected during the summer 2015 field season. While the CSP scientists are unaware
of how the velocity and cross-sectional measurements were made, the town provided
the critical stream flow values (m3/d) to be coupled with the parallel measurements of
total nitrogen concentration data to calculate TN load from these streams to Polipis
Harbor in summer 2015. The flow determined for each sampling day was then used to
determine load for a representative month. The flows and loads are provided below:
24
Measured TN Load TN Load Representative
Sample ID Date Flow Month
(m3/d)(kg/day)(kg/month)
ST3 6/8/2015 365 0.424 12.7 June
ST3 7/6/2015 248 0.385 11.9 July
ST3 8/3/2015 127 0.119 3.7 August
ST3 8/31/2015 40 0.020 0.6 September
ST4 6/8/2015 2040 2.020 60.6 June
ST4 7/6/2015 1771 1.739 53.9 July
ST4 8/3/2015 0 0.000 0.0 August
ST4 8/31/2015 208 0.213 6.4 September
ST6B 6/8/2015 696 0.586 17.6 June
ST6B 7/6/2015 805 1.450 44.9 July
ST6B 8/3/2015 187 0.151 4.7 August
ST6B 8/31/2015 87 0.082 2.5 September
Combining the high TN concentrations with relatively large flows measured at ST4 and
ST6B, it becomes clear that a relatively large TN load can be introduced to Polpis
Harbor from the stream sites on a monthly basis. It is important to note that the large
loads presented would actually be the lowest loads of the year as precipitation during
the summer is typically much lower than in the winter and spring. 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.
Additional estuarine stations (ORS-2,3,4,5,6) were added to the sampling stations in
Nantucket Harbor and Madaket Harbor (ORS-1) specifically to monitor water quality in
the vicinity of potential sites for oyster aquaculture. These stations have never
previously been sampled so it is not possible to compare 2015 results to past years
water quality, however, 2015 results can serve as the beginning of establishing a
baseline for gauging changes in future years. 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. Three stations sampled (ORS-1,5,6) are in addition to
the stations identified prior to the summer 2015 sampling (e.g. Madaket, DucksHolm,
Polpis). Additional analysis will be useful as additional data/information becomes
available.
As noted about past years monitoring results, in reviewing the multi-year monitoring
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 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.
25
Table 2. 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
26
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/blooms). 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, 2014 and 2015) 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 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. 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,b and 8a,b). It should be noted that to the extent the bias exists 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). Given
that inclusion of oxygen data did not generally change the bay health rank, it did yield a
change in the numerical value.
For the present analysis the standard Index 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 18-22 show the distribution of Health
Status throughout each estuary based on each of the 5 years of monitoring (2010, 2012,
2013, 2014, 2015). Numerical results are color coded for ease of interpretation. The
colors of each triangle represent the Bay Health Index status of each site and follow the
designation scheme below:
27
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 5 years of monitoring, although change at some sites 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 5 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. 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 improvement within the upper portions
of this complex estuary is consistent with a lowering of nitrogen loading. Over the 5
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 7, 8, Figure 18). Hither Creek is clearly nitrogen enriched and
showing continuing impairment based on a variety of parameters. However, over the
past 5 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 in 2014 and 2015. 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 stable at high water quality in more recent samplings. 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 can modify 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 sufficient to shift its status in previous years. In
contrast, the offshore sites (3 & 4) support high quality waters resulting from low
nitrogen inputs and very high rates of water exchange. The 5 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
28
is consistent with the upper basin feeding Madaket Ditch, although the lower Long Pond
Station (#5) has varied from year to year without a clear trend. The cause of this inter-
annual variation and the mechanism for the large difference between the 2 Long Pond
stations in needs further analysis. If the improvement in Hither Creek continues, it is
possible that the TMDL for Madaket Harbor may be met, and may reduce some of the
need for other nitrogen management actions. However, it will not be sufficient to meet
the TMDL for Long Pond (see below).
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
18). 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
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 the
water quality of Hither Creek is partially dependent on the nitrogen load from Long Pond
via Madaket Ditch during the ebb tide. However, the Town’s management of the
Landfill, which should reduce the nitrogen load from this source is temporally consistent
with improvements in the water quality Index for Long Pond and the lower TN levels. TN
levels in 2015 were almost half that of historical/2010-11 measurements. While
continued monitoring will determine the level of improvement, it does appear that there a
reduction in N loading may be occurring with beneficial effects. However, even if TN
levels stabilize at 2015 levels, the TN is still high and results in poor clarity, algal
blooms and nutrient related stress to aquatic resources. 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, 2013,2014 and 2015 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. Results from the 2016 should help to determine the level of improvement
expected in coming years.
Nantucket Harbor
Nantucket Harbor with Madaket Harbor are presently supporting the highest water
quality of Nantucket's estuaries. The main basin of Nantucket Harbor is supporting high
quality waters, with only a periodic small level of decline in the uppermost basin,
Wauwinet basin (Figure 19). 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 station 2A (the official MEP sentinel station for which the nitrogen threshold was
established, refer to Figure 15) will be added to the monitoring along with station 3 in
order to meet TMDL compliance monitoring criteria. Summer 2015 showed similar water
quality in this basin as 2010 and 2012, contrasting with the 2014 results which showed
improved chlorophyll-a and TN levels versus prior years. The main driver of the 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. It is
29
unclear if this will become more commonplace in the future and should be monitored.
However, other activities associated with the Harbor (additional sewer hookups, jetty
improvement and oyster aquaculture) may offset any underlying trend. A similar pattern
was seen in the enclosed sub-basins of Polpis Harbor (East and West) which continue
showing moderate impairment and moderate nitrogen enrichment, although appear to
have improved over historic conditions. As in Wauwinet, Polpis Harbor showed TN
levels similar to 2010 and 2012 which were higher than 2013 and 2014. This variation
makes continued monitoring essential to clarify any trends in water quality. However,
unlike Wauwinet, Polpis did not show a phytoplankton bloom and supported only
moderate-low phytoplankton biomass in 2015 (~4 ug/L) and appears to have attained
moderate-high water quality status. While the overall Nantucket Harbor System 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
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 and 2015 results showed a partial
return to historic levels 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 2010-2013 period were stabilizing at moderate level of estuarine health,
with the past 2 seasons seeing a significant trend toward poor water quality conditions
(Figure 20). Additional higher level assessment of Sesachacha Pond initiated by the
2010 monitoring results has been conducted which confirms that the pond was
improving by 2013, but was impaired in 2014 consistent with the monitoring results. The
2015 data underscores the reversal of improvement with phytoplankton biomass (as
chlorophyll) averaging >10 ug/L at all stations over the summer, indicative of a
significant nitrogen enrichment. The high chlorophyll values are consistent with the high
TN values in 2014 and 2015. 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
30
quality of 2012 and 2013 (done under Town supervision) in the future may be sufficient
to attain the TMDL for this system. 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 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). There is a small gradient in water quality with
moderate to poor conditions near the ocean and poor conditions in the uppermost
basins (Figure 21). 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, 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.
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 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 it is still
above its threshold value to support high quality habitat. This opening program and
associated monitoring around the openings and in the summer should be continued 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 resulted in significant benefits to
Hummock Pond water quality and associated natural resources at low cost to the Town.
31
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, reaching a low of 0.1 ppt in 2015. 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 22). 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 with 2015 continuing the trend (38-53 ug/L) and supporting the highest
chlorophyll a levels throughout the pond of the years measured (as opposed to at a
single station). All of the metrics are consistent with a nutrient impaired basin.
However, as the freshening of this basin has continued, 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 overwash in the future, 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 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. But at present the
system is a highly nutrient impaired aquatic system with poor water quality.
Recommendations for Future Monitoring
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 should be considered for this analysis at some time in the future
(e.g. summer 2016). It may also be timely to complete a higher level assessment of
Miacomet Pond as that large salt pond has been showing consistently poor water quality
and low trophic status indicative of an impaired habitat and is becoming a freshwater
basin. 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.
32
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 - 2015 appear to show a significant reduction in
TN over historical conditions and 2010. The TN pattern in 2014 suggested
that there may be a restriction to mixing between station 5 and 6 which should
be investigated and if possible managed. Additionally, the TN data in 2015
showed a continuing decrease in TN levels with a significant drop from 2014
at both stations in the pond (station 5 {1.481 dropped to 0.697}, station 6
{0.788 dropped to 0.656}).
Additionally, it should be noted that the stream stations discharging to Nantucket Harbor
(specifically Polpis Harbor) which were not sampled in 2012, 2013 or 2014 were sampled in
2015. 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 2016 sampling
season given the high concentrations of total nitrogen observed in 2015 that are discharging to
this tributary sub-embayment. The utility of these data would be greatly enhanced if sampling
was paired with flow measurements to allow determination of both the concentration of stream
water and the nitrogen load discharged to the Harbor from each streams watershed and to
gage the degree to which the loads these streams contribute to the TN concentration at the
sentinel station in Polpis Harbor. While concentrations are high at stations 3, 4 and 6b (1.218,
1.060, 1.184 mg/L respectively) loads may be moderate depending on the flow rate at each
stream sampling point.
Miacomet continues to show poor and worsening trophic conditions, high TN concentrations at
stations 1, 2, and 3 (1.297, 1.318, 0.992 respectively) and extremely high total pigment (CHLA
+ pheophytin) in 2015. In light of yet another year of decreasing 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. 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 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 should be
formalized and rigorously implemented as monitoring clearly showed that if specific
conditions are taken into consideration during a given opening, the ensuing opening will
tend to be effective thereby having a clear positive impact on water quality in Hummock
Pond and indeed Hummock Pond water quality has significantly improved under the
revised opening protocol by the Town. Management should continue to 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.
Additionally, it is critical to carefully document conditions during a given opening (pond
water levels before during and after the opening, water quality, wind direction, wave
conditions {size and direction}, tidal state {spring vs. neap}, size of opening {depth and
width} and duration of opening) in order to continue building up a quantitative basis for
33
refining openings and maximizing the improvement of water quality in Hummock Pond.
Similarly, the opening protocol should be implemented for openings of Sesachacha
Pond as monitoring has indicated that water quality improved in Sesachacha Pond
(2010-2013) compared to historical MEP mean (1992-2005) and that is most likely
directly related to the effectiveness of openings as loads into the pond are low and not
necessarily decreasing. However, this trend toward restoration has reversed with TN
levels in 2014 and 2015 (0.919 and 0.918 mg/L respectively) rising compared to levels in
2010,12,13 (0.684, 0.678, 0.714 mg/L respectively). Details of the openings in 2014 and
2015 should be compiled and compared to the openings completed in 2010, 2012 and
2013 in order to ascertain the difference between openings and future openings in 2016
should be monitored to continue building up the database of what constitutes an
effective opening in both Sesachacha Pond and Hummock Pond. The data base will
serve to strengthen and refine the Ponds Opening Protocol.
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 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
Nantucket that Nantucket’s estuaries are being protected and in some cases already moving
toward restoration.
34
Table 2a. 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. Further study should investigate
the possibility and TP paired with salinity should continue to be monitored during the summer 2016 field season.
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
35
Table 2b. 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
36
Table 2c. 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
37
Table 2d. 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
38
Table 2e. 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
39
Figure 14. Comparison of nitrogen species (mg/L) in Nantucket Harbor in summers, 2010-2013 avg. (upper left); 2014 (upper right); 2015
(bottom) Total nitrogen is the sum of the inorganic and organic fractions (top line in each graph). All figures are to same scale.
40
Figure 14 cont'd. Comparison of nitrogen species (mg/L) in Hummock Pond in summers, 2010-2013 avg. (upper left); 2014 (upper right);
2015 (bottom). Total nitrogen is the sum of the inorganic and organic fractions (top line in each graph). All figures are to same scale.
41
Figure 14 cont'd. Comparison of nitrogen species (mg/L) in Sesachacha Pond in summers, 2010-2013 avg. (upper left); 2014 (upper right);
2015 (bottom). Total nitrogen is the sum of the inorganic and organic fractions (top line in each graph).
42
Figure 14 cont'd. Comparison of nitrogen species (mg/L) in Madaket Harbor in summers, 2010-2013 avg. (upper left); 2014 (upper right);
2015 (bottom). Total nitrogen is the sum of the inorganic and organic fractions (top line in each graph). All figures are to same scale.
43
Figure 14 cont'd. Comparison of nitrogen species (mg/L) in Long Pond (Madaket Harbor System) in summers, 2010-2013 avg. (upper left);
2014 (upper right); 2015 (bottom) Total nitrogen is the sum of the inorganic and organic fractions (top line in each graph). All figures are to
same scale.
44
Figure 14 cont'd. Comparison of nitrogen species (mg/L) in Miacomet in summers, 2010-2013 avg. (upper left); 2014 (upper right); 2015
(bottom). Total nitrogen is the sum of the inorganic and organic fractions (top line in each graph). All figures are to same scale.
45
Figure 15. 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.
46
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.
2 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)
2015
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 0.436
Head of the Harbor -
Lower 2A 0.339 0.070
NA NS NS NS
NS NS
Pocomo Head 3 0.335 0.081 NA 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
East Polpis Harbor 4+Town 6 0.362 0.105 6 0.438 0.484 0.401 0.378 0.404
West Polpis Harbor 4A+Town 5 0.388 0.119 5 0.431 0.419 0.385 0.389 0.422
Abrams Point 5 0.335 0.060 NA NS NS NS NS NS
Monomoy 6 0.297 0.086 NA 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 0.39, 0.33
Nantucket Sound OS+Town 4 0.239 0.041 4 0.283 0.3442 0.3171 0.277 0.297
47
Figure 16. 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.
48
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)
2015
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) 0.918 (0.904)
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 ( ).
49
Figure 17. Estuarine water quality monitoring station locations in the Madaket Harbor and Long Pond Systems.
50
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.
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)
2015
Mean TN
(mg/L)
Madaket Harbor MEP M1 0.336 0.098
Madaket Harbor Town 4 0.285 0.297 0.278 0.254 0.328
Madaket Harbor MEP M2 0.395 0.083
Madaket Harbor Town 2 0.436 0.444 0.323 0.347 0.418
Madaket Harbor MEP M3 0.415 0.090
Madaket Harbor Town 3 0.324 .356 0.314 0.376 0.324
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
0.524
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
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
0.656
North Head Long P. MEP LOPO5 0.954 0.271
51
Hummock Pond
and
Miacomet Pond
Station ID's
2015 2014 2013 2012 2010 2005/2007
TN
(mg/L)
TN
(mg/L)
TN
(mg/L)
TN
(mg/L)
TN
(mg/L)
TN
(mg/L)
Mean Mean Mean Mean Mean Mean S.D.
HUM1 0.539 0.651 0.769 0.666 0.616 0.751** 0.374
HUM3 0.622 0.643 0.827 0.863 0.589 0.630** 0.388
HUM5 0.558 0.653 0.881 0.871 0.766 ND ND
HUM7 0.621 0.873 1.170 1.301 1.786 1.283** 0.969
HUM8 0.576 0.755 1.064 0.944 0.983 ND ND
MP1 1.297 0.864 0.792 0.828 0.854 0.842* 0.191
MP2 1.318 0.784 1.036 0.880 0.811 0.855* 0.213
MP3 0.992 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, 2014 and 2015. All values are mg/L.
52
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
Table 7. 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).
53
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 7a. 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).
54
Table 7b. 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
55
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 7c. 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).
56
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 7d. 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).
57
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
Table 8. 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).
58
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 8a. 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).
59
Table 8b. 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
60
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 8c. 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).
61
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 8d. 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).
62
Figure 18. Madaket Harbor Eutrophication Index 2010 (top triangle) and 2015 (bottom triangle). Index was calculated with dissolved oxygen.
Colors indicate High (Blue), Moderate (Yellow), Fair/Poor (Red) nutrient related water quality.
63
Figure 19. Nantucket Harbor Eutrophication Index 2010 (top triangle) and 2015 (bottom triangle). Index was calculated with dissolved
oxygen. Colors indicate High (Blue), Moderate (Yellow), Fair/Poor (Red) nutrient related water quality.
64
Figure 20. Sesachacha Pond Eutrophication Index 2010 (top triangle) and 2015 (bottom triangle).
Index was calculated with dissolved oxygen. Colors indicate High (Blue), Moderate (Yellow), Fair/Poor
(Red) nutrient related water quality.
65
Figure 21. Hummock Pond Eutrophication Index 2010 (top triangle) and 2015 (bottom triangle). Index
was calculated with dissolved oxygen. Colors indicate High (Blue), Moderate (Yellow), Fair/Poor (Red)
nutrient related water quality.
66
Figure 22. Miacomet Pond Eutrophication Index 2010 (top triangle) and 2015 (bottom triangle). Index
was calculated with dissolved oxygen. Colors indicate High (Blue), Moderate (Yellow), Fair/Poor (Red)
nutrient related water quality.