HomeMy WebLinkAbout2016 Final Water Quality Report 1
Technical Memorandum
FINAL
Water Quality Monitoring and Assessment of the
Nantucket Island-Wide Estuaries and Salt Ponds
Update 2016
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
February 1, 2017
2
The Technical Memorandum on the 2016 Nantucket Water Quality Monitoring Program is
organized consistent with previous SMAST water quality monitoring summaries (2010 and 2012
- 2015) to allow direct comparison to data from the previous years of monitoring. However, the
2016 summary does not include an overview of the program or the summary of the sampling
approach as neither of those two sections have changed from previous years, instead they are
included by reference. The 2016 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 2016 water quality monitoring of Nantucket's fresh and
saltwater systems was focused on summer-time conditions, as the warmer months
typically have the lowest water quality conditions hence the critical period of resource
management. As in previous years (2010, 2012-2015), the 2016 approach utilized for
the collection and analysis of water samples from each of the estuaries of Nantucket
remains the same. This consistency is intended to maximize the value of the results by
making the data perfectly cross-comparable to water quality monitoring data collected
across the Island of Nantucket from previous years and 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 to formulate
appropriate nutrient management strategies. This allows individual towns such as
Nantucket to directly benefit from lessons learned throughout the wider region. It should
be noted that in 2016, compliance monitoring samples were collected from sentinel
locations in Nantucket Harbor, Sesachacha Pond and Madaket Harbor as established
under the Massachusetts Estuaries Project. Those samples are required of the Town by
MassDEP and are denoted by a (C) in the sample ID.
As in past years, UMD-SMAST Coastal Systems Program (CSP) scientists focused
primarily on the analysis of samples collected from the field effort 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:
3
1. determine the present (2016) ecological health of each of the main salt ponds and
estuaries within the Town of Nantucket,
2. gauge (as historical data allows) the decline or recovery of various salt ponds and
embayments over the long-term (also part of TMDL compliance), and
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 required to develop cost-effective
targeted solutions.
As was the case in 2010, 2012, 2013, 2014 and 2015 sampling efforts, the 2016
sampling program focused on the summer/early fall months (May-September). In the
case of Sesachacha Pond 2 additional sampling events were completed to monitor the
efficacy of the spring opening (breaching barrier beach) and in Hummock pond an
additional event was completed in April to represent pre-opening conditions and the
regularly scheduled May sampling event was utilized to determine water quality in the
pond after the pond closed. 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 (2016), Table 1b (2015), Table 1c (2014), Table 1d (2013), Table 1e (2012), and
Table 1f (2010). Samples collected in 2016 were obtained from the same sampling
station locations and the same depths as in previous years to maximize cross
comparability and to gauge temporal changes. It should be noted that the Town of
Nantucket did undertake water quality monitoring in 2011, however, those samples were
analyzed by a lab other than the Coastal Systems Analytical Facility at the UMASS
School for Marine Science and Technology. The 2011 water quality data were presented
in tabular form in Appendix A in Annual Technical Memoranda of 2012 and 2013 and are
not being reproduced again herein.
The physical/environmental parameters measured in the estuaries during the 2016
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. As
initiated in the summer of 2015, the estuarine water quality monitoring undertaken in
2016 included an additional 3 stream locations. During the summer 2016 season, stream
station STA-3 was dropped due to no flow and a station STA-4a was added to clarify
water quality conditions in the stream outflow associated with cranberry bogs up-gradient
of STA-4. In 2016, 37 field duplicates (17% of the total number of samples collected
{n=216}) 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.
4
The Town of Nantucket has been working for decades to protect and more recently
restore its estuaries and their aquatic resources. At present, activities to lower nitrogen
enrichment and its negative impacts to water and habitat quality are 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 detailed below, summer 2016 appears to have sustained high water quality for the
Nantucket Harbor stations (2016 embayment wide TN average 0.35 mg/L, 2015 = 0.37
mg/L). Hummock Pond water quality in the summer of 2016 showed a decrease in
overall water quality compared to 2015 (2016 embayment wide average TN = 0.80 mg/L,
2015 = 0.58 mg/L), possibly due to higher precipitation, as the spring opening in 2016
compared well with the duration of the opening in 2015 (18 days and 15 days
respectively). TN concentrations continue to trend toward improved conditions in Long
Pond and a slight improvement was seen in Miacomet Pond as seen in the lower TN
concentration and lower total pigments (CHLA + Pheophytin). The 2016 water quality
analysis confirmed that the significant improvement in Sesachacha Pond seen previously
has diminished and the Pond has declined in nitrogen related water quality over the past
3 years (2014, 2015, 2016) possibly due to the efficacy of the inlet openings (5 day
opening spring 2015 and 3 day opening spring 2016). If so, this recent decline should be
readily reversible.
Table 1a. Sampling Schedule for 2016 Nantucket Water Quality Monitoring Program
Month Nantucket
Harbor
Madaket
Harbor
Long
Pond
Sesachacha
Pond
Miacomet
Pond
Hummock
Pond
Polpis
Streams
Oyster
Sites
Jan
Feb
Mar March 16
April April 6,25 April 11 April 20
May May 9 May 11 May 12 May 18 May 18 May 10 May 17 May 12
June June 8, 23 June 7 June 6 June 15 June 15 June 13 June 14 June 27
July July 8, 25 July 6,28 July 13 July 5,18 July 5 July 13 July 21 July 11
August Aug 8,23 Aug 10,24 Aug 4 Aug 3 Aug 3 Aug 4 Aug 25
September Sept 21 Sept 22 Sept 19 Sept 12 Sept 13 Sept 19 Sept 20
October
November
December
Total
Events
8 7 5 8 5 6 5 5
5
Table 1b. Sampling Schedule for 2015 Nantucket Water Quality Monitoring Program
Table 1c. Sampling Schedule for 2014 Nantucket Water Quality Monitoring Program
Note: * The September 15 sampling of Nantucket Harbor only involved one station (NAN-4).
Month Nantucket
Harbor
Madaket
Harbor
Long
Pond
Sesachacha
Pond
Miacomet
Pond
Hummock
Pond
Polpis
Streams
Oyster
Sites
Jan
Feb
Mar
April
May May 7 May 12 May 11 May 11 May 12, 27
June June 9, 22 June 8 June 17 June 15 June 15 June 17 June 8 June 9
July July 8, 20 July 6 July 13 July 15 July 15 July 13 July 6 July 6
August Aug 4,19 Aug 5 Aug 17 Aug 10 Aug 10 Aug 12 Aug 3, 31 Aug 3
September Sept 1 Sept 3 Sept 14 Sept 10 Sept 10 Sept 9 Sept 2
October
November
December
Total
Events
8 4 5 5 5 6 4 4
Month Nantucket
Harbor
Madaket
Harbor
Long Pond Sesachacha
Pond
Miacomet
Pond
Hummock
Pond
Jan
Feb
Mar
April
May May 6 May 14 May 20 May 14 May 7, 19
June June 4, 17 June 19 June 11 June 12 June11 June 10
July July 1, 17 July 2 July 23 July 30 July 30 July 23
August Aug 4, 14 Aug 18 Aug 21 Aug 19 Aug 19 Aug 21
September Sept 2, 15* Sept 15 Sept 4 Sept 4 Sept 18 Sept 18
October
November
December
Total Events 8 4 5 5 5 6
6
Table 1d. Sampling Schedule for 2013 Nantucket Water Quality Monitoring Program
Table 1e. Sampling Schedule for 2012 Nantucket Water Quality Monitoring Program
Month Nantucket
Harbor
Madaket
Harbor
Long Pond Sesachacha
Pond
Miacomet
Pond
Hummock
Pond
Jan
Feb
Mar
April
May May 28 May 22 May 22 May 21
June June 13, 25 June 12 June 4,26 June 5 June 5 June 6
July July 17, 30 July 16 July 10 July 9 July 9 July 2
August Aug 13, 28 Aug 12 Aug 21 Aug 21 Aug 6 Aug 14
September Sept 9 Sept 10 Sept 24 Sept 19 Sept 24 Sept 18
October
November
December
Total Events 7 5 5 5 5 5
Month Nantucket
Harbor
Madaket
Harbor
Long Pond Sesachacha
Pond
Miacomet
Pond
Hummock
Pond
Jan
Feb
Mar
April
May May 29
June June 7, 28 June 12 June 25 June 20 June 20 June 27
July July 9, 26 July 11 July 24 July 19 July 19 July 31
August Aug 7, 22 Aug 8 Aug 21 Aug 23 Aug 23 Aug 24
September Sept 6 Sept 7 Sept 25 Sept 25 Sept 27 Sept 26
October
November
December
Total Events 8 4 4 4 4 4
7
Table 1f. Sampling Schedule for 2010 Nantucket Water Quality Monitoring Program
Month Nantucket
Harbor
Madaket
Harbor
Long Pond Sesachacha
Pond
Miacomet
Pond
Hummock
Pond
Streams
Jan
Feb
Mar
April
May May 18 May 20 May 19 May 26 May 26 May 25
June June 2, 17 June 3, 15 June 17 June 24 June 24 June 29 June 28
July July 1, 15,
30
July 16, 27 July 29 July 26 July 26 July 28
August Aug. 13 Aug. 12, 30 Aug. 11 Aug. 26 Aug. 26 Aug. 27
September Sept. 1, 14 Sept. 13 Sept. 15 Sept. 23 Sept. 23 Sept. 28
October Oct. 21
November
December
Totals 10 8 5 5 5 5 1
8
Figure 1. Madaket Harbor and Long Pond sampling stations 2010, 2012, 2013, 2014, 2015 and 2016.
9
Figure 2. Nantucket Harbor sampling stations 2016. Station NAN-8 (the cut) was only sampled in 2010 and location changed in 2011 -
2016. Nantucket Harbor and Polpis Harbor each have nitrogen thresholds in the MassDEP/USEPA TMDL for this system.
10
Figure 3. Sesachacha Pond sampling stations 2010, 2012, 2013, 2014, 2015, 2016.
11
Figure 4. Hummock Pond sampling stations 2010, 2012, 2013, 2014, 2015, 2016. Station 7 is in Head of Hummock, a kettle pond
connected by an artificial channel to the estuary with limited exchange from Station 7 to Station 8.
12
Figure 5. Miacomet Pond sampling stations 2010, 2012, 2013, 2014, 2015, 2016.
Station 3
Station 1
Station 2
Station 3
Station 1
Station 2
13
Figure 6a. Polpis Harbor Stream Sampling locations (ST-4, 4A, 6B) 2016 (shown as yellow
pins). Water samples from mid depth in water exiting culverts.
Figure 6b. Polpis Harbor Stream Sampling locations (ST-3,4,6B) 2015 (yellow pins). Water
samples from mid depth in water exiting culverts. ST-3 was dropped in 2016 due to zero flow.
14
Figure 7a. Oyster Aquaculture Sampling locations Nantucket Harbor (ORS-2,3,4,5,6) and Madaket
Harbor (ORS-1) sampled in 2015. ORS-2,4,6 sampled in 2016. Sites are associated with possible
oyster aquaculture areas (yellow pins).
Figure 7b. Oyster Aquaculture Sampling location Madaket Harbor (ORS-1) 2015 (yellow pin). Site is
associated with possible oyster aquaculture areas.
15
Summary of 2016 Water Quality Results for Nantucket Sampling
While there were some localized areas supporting apparent temporal changes in water
quality (Hummock Pond {-}, Miacomet Pond {+}, Long Pond {+}1, see below), the overall
trends in water quality observed in 2016 follow and expand the pattern observed in
2010, 2012, 2013, 2014 and 2015. As in previous years, water samples collected from
May through September in the estuarine systems indicate that organic nitrogen
(dissolved + particulate) still dominates the Total Nitrogen pool (92%-98% in 2016
depending on the estuary vs. 96% in 2015 alone), while bio-available nutrients in the
form of nitrite and nitrate (NOx) and ammonium (NH4) account for 2% - 10% of the TN
pool in 2016 compared to 4% of Total Nitrogen pool in 2015 (Tables 3a,b,c,d,e, f and
Figures 14,15). 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.
It is the uptake of bio-available nitrogen, entering via groundwater to estuarine waters,
primarily by phytoplankton that is transforming inorganic to organic nitrogen and under
nitrogen enrichment is the mechanism through which water quality becomes impaired.
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 2016 (Table 3a), as noted in prior years as well (Tables 3b,c,d,e,f).
Consistent with the water clarity and TN levels, corresponding chlorophyll-a pigment
concentrations were lowest (1-5 ug/L) in these well flushed systems (Table 3a,b,c,d,e,f
Figure 8,9). The observed level of variation is common and underscores the need for
multi-year monitoring to establish trends.
Nantucket Harbor and Madaket Harbor are both well flushed basins and tended to have
slightly lower phytoplankton biomass (chlorophyll-a) in 2016 compared to 2015 (all
stations in Madaket Harbor and most stations in Nantucket Harbor). In Nantucket
Harbor, station Nan-5 showed a higher level of total pigment in 2016 compared to 2015,
however, the difference was slight and the levels in both years was relatively low (5.8
ug/L and 3.8 ug/L respectively). In Madaket Harbor the total pigment levels in 2016
were consistently low compared to most other years including 2010. This is consistent
with the water clarity observed in 2016 (Nantucket Harbor station 3 secchi depth 2015 =
1.45 m, 2016 = 2.34 m, Madaket Harbor MH-2 secchi 2.2 meters in 2015, 1.7 meters in
2016) as turbidity is primarily the result of organic particulates, e.g. phytoplankton. The
parallel measurements of total nitrogen (TN) are generally consistent with the
chlorophyll-a results, showing a positive relationship between changes in TN levels with
changes in chlorophyll-a levels (see below). This is particularly apparent in Nantucket
Harbor (station 5 and 6, Polpis) and provides additional evidence that nitrogen is
controlling the level of eutrophication in these systems.
1 {+} indicates improved conditions in 2016; {-} indicates declining conditions in 2016.
16
Figure 8. Average Chlorophyll-a (CHLA) concentrations by station in the well flushed
Nantucket Harbor system during the summer 2016 sampling season. Stations Nan-5
and 6 are in Polpis Harbor the rest relate to the main basin. Note that 2016 levels were
about average within the upper basins (Nan-5 slightly higher in 2016 compared to 2015)
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 2016 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 and 2016 total pigment levels were
slightly lower than in 2015, similar to the lower reaches of Nantucket Harbor.
17
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 the open basins of
Nantucket and Madaket Harbors. Chlorophyll-a concentrations in the poorly flushed
basins of Long, Hummock, Miacomet and Sesachacha Ponds in 2016 were 4.1 ug/L
(max. 6.8 ug/L), 5.1 ug/L (max. 44.8 ug/L), 11.8 ug/L (max. 43.1 ug/L) and 5.6 ug/L
(max. 10.5 ug/L), respectively (Table A, Figures 10, 11,12,13). These general patterns
were also observed in the monitoring results of the prior year (2015 average chlorophyll-
a, 5.4 ug/L, 4.5 ug/L, 41.3 ug/L and 6.8 ug/L) with highest chlorophyll levels also being
observed in Miacomet Pond. It should be noted that the chlorophyll-a levels in Long
Pond, Miacomet Pond and Sesachacha Pond all appear to be lower when compared to
2015 average values but in Hummock Pond the values were slightly higher. In
Hummock Pond chlorophyll-a levels have risen slightly in 2016 compared to 2015,
possibly due to a less effective opening compared to the prior years of 2012, 2013,
2014 and 2015, though the duration of the 2016 opening was about the same as in
2015. Interestingly, average total pigment values (chlorophyll-a + pheophytin) were
significantly lower in Miacomet Pond in 2016 compared to 2015 (15.5 ug/L vs. 48.7
ug/L).
The multi-year results clearly show that 2010 was a poor water quality year as was also
seen in each of Nantucket’s estuaries. Over the past 4 years, chlorophyll-a levels in
Long Pond, Hummock Pond, Miacomet Pond and Sesachacha Pond have dropped
compared to historic levels and 2010 but do show variation (e.g. all ponds higher in 2015
compared to 2014). However, Sesachacha Pond and Hummock Pond have showed
much improved water quality compared to their long term status during the MEP
assessment where Sesachacha Pond showed historic chlorophyll-a levels generally >20
ug/L, frequently >60 ug/L and blooms as high as 100 ug/L. It is becoming clear that that
Hummock Pond and Sesachacha Pond water quality is tightly linked to the success of
its periodic openings. Sesachacha Pond showed significantly improved conditions in
2012 and 2013, but has recently showed declines in 2014, 2015 and 2016, but not to
historic levels. This was clearly seen in 2014, 2015 and 2016 with TN levels appearing
higher in 2016 than in 2015 and 2014 with an associated increase in total pigment levels
(potentially related to a less effective opening in 2016 {3 day spring opening} compared
to 2015 {5 day spring opening}). The temporal data indicate that both Sesachacha
Pond and Hummock Pond can be significantly restored by effective 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). The
concept is that guidance derived from the empirical response in water quality relative to
opening metrics may assist the Town in refining what is a difficult process of pond
openings.
After the high chlorophyll-a levels in 2010, 2012, Long Pond has maintained its
phytoplankton levels at a moderate to high level, with 2016 showing the lowest levels of
record. The initial decline (post-2012) was noted in the previous 3 monitoring years and
is possibly a result of activities at the landfill leading to declining nitrogen inputs to
pondwaters. As previously recommended, a detailed assessment of the current landfill
effect on groundwater quality flowing to Long Pond would be critical to linking activities
18
at the landfill with improvements observed in Long Pond and for making predictions as
to the likely extent of improvement possible. Presently, however, Long Pond though
improving, continues to be eutrophic and impaired based upon the suite of water quality
metrics. In contrast to the improvements seen in Long Pond, Miacomet Pond which is
not open to tidal flows and has become very fresh (avg. salinity 0.10 ppt), continues to
show high chlorophyll-a levels (10-20 ug/L seasonal average), although 2016 levels
were generally lower than 2013 and 2015). Miacomet Pond is still clearly supporting
poor water quality conditions with high TN and chlorophyll-a levels, poor water clarity
and moderate oxygen depletion, all indicators of a nutrient impaired basin.
The upper portion (Hum-8 and Hum-5) of Hummock Pond showed overall total pigment
and chlorophyll-a levels in summer 2016 were lower than 2010, 2012, 2013 and show
moderate levels in the mid reaches but with stations in the lower portion (Hum-1 and
Hum-3) closer to the barrier beach having slightly lower total pigment levels compared to
most years. The 2014 results remain the lowest levels measured over the 2010-2016
monitoring period and while 2016 was slightly higher than 2015 in the upper reaches of
the system, chlorophyll levels in 2016 were still moderate-high as a metric of
eutrophication. While three years (2014, 2015 and 2016) represent the beginning of a
restoration trend, the lower levels in these three years are consistent with an improved
opening protocol implemented in 2014. The new protocol stems from the Town and the
Nantucket Land Council supporting a project specifically to refine the opening protocol
for Hummock Pond to maximize the amount of tidal flushing achieved by each opening.
The April 2014 opening of Hummock Pond was moderately successful and was followed
by a more effective opening that Fall (October 2014) which lowered TN levels in the
pond and raised its salinity. In 2015, the revised opening protocol allowed for a 15 day
spring opening and a 17 day fall opening further flushing the pond. This was followed by
a 18 day spring opening in 2016 in advance of the summer sampling season. It is
almost certain that the sequence of good openings was the cause of the relatively low
total pigment and TN conditions in the lower half of Hummock Pond in 2016. As flushing
in the uppermost portions of Hummock Pond tend to be limited, total pigment and
chlorophyll-a showed to be similar (though slightly higher) compared to 2015. Total
pigment and chlorophyll-a generally remains the lowest at each monitoring station in
2014 when compared to prior years. In April 2016 and 2015, Hummock Pond was
opened and water levels and water quality were monitored before and after the opening.
Both the April 2016 and 2015 openings did appear to be more effective than the fall
2014 opening thereby contributing to the enhanced water quality observed during the
summer 2016 and 2015. Not surprisingly, in 2016 at station Hum-8 which showed
elevated total pigment levels compared to 2015, average TN levels in the summer of
2016 were also higher than in summer 2015 (1.19 mg/L and 0.576 mg/L respectively).
Additionally, at station Hum-7 which showed similar total pigment levels compared to
2015, average TN levels in the summer of 2016 were nearly the same as in summer
2015 (0.674 mg/L and 0.621 mg/L respectively). In general, it appears that the water
quality in Hummock Pond does respond well to longer inlet openings as achieved in the
spring of 2016 (18 days) and spring of 2015 (15 days). As water quality conditions in
2016 and 2015 are generally similar under nearly similar duration openings, it is possible
that the pond is reaching equilibrium with the hydrodynamic conditions of a given
opening. Further improvements are anticipated if openings can be made longer than 18
days or loads to Hummock Pond reduced. The opening protocol will be further refined
as appropriate as additional data from future openings becomes available.
19
Table A - 2016 Minimum, Maximum and Average CHLA and Total Pigment values for
the closed ponds of Nantucket.
min max avg min max avg
System CHLA CHLA CHLA Total Pig Total Pig Total Pig
(ug/L)(ug/L)(ug/L)(ug/L)(ug/L)(ug/L)
Miacomet Pond 2.88 43.05 11.82 5.44 58.35 15.52
Sesachacha Pond 2.92 10.51 5.60 3.54 10.54 6.68
Long Pond 1.52 6.80 4.14 2.55 9.67 6.12
Hummock Pond 0.86 44.86 5.11 1.62 46.18 7.52
Table B - 2015 Minimum, Maximum and Average CHLA and Total Pigment values for
the ponds of Nantucket with limited or only periodic tidal exchange.
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 Total Pigment (Chlorophyll-a +Pheophytin) concentrations by station
in the Long Pond portion of the Madaket Harbor system during the summer 2016
sampling season compared to 2010, 2012, 2013, 2014 and 2015.
20
Figure 11. Average Total Pigment (Chlorophyll-a +Pheophytin) concentrations by station
in the seasonally opened Hummock Pond system, during the summer 2016 sampling
season compared to 2010, 2012, 2013, 2014 and 2015.
Figure 12. Average Total Pigment (Chlorophyll-a +Pheophytin) concentrations by station
in the Miacomet Pond system during the summer 2016 sampling season compared to
2010, 2012, 2013, 2014, 2015 Miacomet Pond is not opened to the Atlantic Ocean and
now contains freshwater.
21
Figure 13. Average Total Pigment (Chlorophyll-a +Pheophytin) concentrations by station
in the seasonally opened Sesachacha Pond system during the summer 2016 sampling
season compared to 2010, 2012, 2013, 2014 and 2015.
Average Total Nitrogen values for all of Hummock Pond (MEP TN threshold = 0.50
mg/L, HUM-3) were higher in 2016 even though total pigment appeared slightly lower in
the bottom half of the pond and slightly higher in the upper half compared to 2015. Total
nitrogen averaged 0.797 mg/L in 2016 whereas in prior years [2015, 2014, 2013, 2012,
2010] average TN values were [0.583, 0.715, 0.900, 0.923, 0.944] mg/L respectively.
However, the pattern for the whole of Hummock Pond is somewhat deceptive given the
strong TN gradient from the upper stations (Hum 7 & 9) and the lower stations (Hum 1 &
3). The lower stations, most influenced by the breaches, showed the largest
improvement 2014-2016, with 2016 showing the lowest TN levels to date. 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. Relative to the 2012-2016 and 2010 data sets, results indicate that within
Hummock Pond, less so Long Pond and Miacomet Pond, there is a general gradient of
nutrient (N and inorganic P) and chlorophyll concentrations from high levels in the upper,
more enclosed and poorly flushed reaches of the estuaries to lower concentrations
closer to the outlets where flushing is more effective (Figure 14,15). The gradient
appears to be a bit flatter in 2016 for both Long Pond and Miacomet Pond. Based on
average TN values in Hummock Pond, water quality in 2016 appears lower compared to
2015 and not able to meet the nitrogen threshold needed for restoration.
In contrast, Miacomet Pond (No MEP threshold set) which has had no restoration
activities or openings in recent decades showed lower TN levels in 2016 (0.742 mg/L)
compared to 2015 (1.203 mg/L) and to the previous 4 years of monitoring [1.202, 0.982,
0.962, 0.919, 0.886]. It is not clear what caused the shift in 2016, but as a freshwater
pond, Miacomet is highly influenced by freshwater inflows and may be responding to the
22
current drought in this manner, but this is purely speculative and would need site-
specific confirmation. It should be noted that lower Miacomet Pond’s TN levels are still
quite elevated and the pond is clearly impaired by excess nutrients (N & P). The high
levels of TN in these poorly flushed estuaries clearly contrast with the levels of TN and
pigment in Nantucket’s well flushed estuaries (Nantucket and Madaket Harbors). The
effect of flushing is to increase the sensitivity of an estuary to nutrient inputs as water
exchange rates are diminished.
As stated above, Miacomet Pond continues to be fresh and impaired by excess
nutrients. Average TN values in 2014 were generally similar to 2013 (0.982 mg/L vs.
0.962 mg/L), TN values in 2015 were high (1.202 mg/L) but reduced in 2016 (0.742
mg/L, even lower than 2014 and 2013). Chlorophyll-a levels were also significantly
lower in 2016 compared to 2015 and 2015 still remains the highest level observed
compared to all previous years. However, at its present low/no salinity (freshwater), it is
not clear what is the primary nutrient for management (N, P, or N+P). Miacomet Pond
in 2016 as in 2015 and 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 2016-2014 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 in 2016 of 7.3, 6.9, 8.6 and in 2015 6.5, 6.8, 6.5
respectively, Redfield C/N ratio is 6.62). This supports the contention that
phytoplankton comprise almost all of the particulate matter in the pond. The nutrient
data showed significant variation between the pond basins, with total N/P ratios lower at
the head and increasing to the middle and lower portions (MP3 - MP1 - MP2, for a total
N/P ratio of 26.8, 37.9, 21.8, a similar pattern to 2015 ratios at these stations of 16.9,
36.9, 34.4 respectively, Redfield N/P ratio is 16). In freshwater basins, Ratios
significantly greater than 16 (i.e. >20) indicate that phosphorus additions likely result in
increased eutrophication and that Phosphorus should be a focus of pond management.
This is the case throughout Miacomet Pond in 2016, although only for the middle and
lower pond in 2015. It is likely that regions of the pond may be sensitive to both nitrogen
and phosphorus, such that overall both nutrient need to be monitored and considered for
management of Miacomet Pond, although phosphorus management is clearly needed at
this time.
To refine this approximation of the limiting nutrient for Miacomet Pond, nutrient ratios from the
monitoring effort should be coupled to 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 and Cockeast Pond in Westport, specifically to better determine the degree of N or P
limitation in these coastal salt ponds 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 variation in N/P ratios in the different basins of the
pond suggests that some regions could be either N limited or P limited (or both). A more
23
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. All of
the estuarine stations in Nantucket’s estuaries are clearly nitrogen limited, based upon various
assessments including the MEP.
Table C - below shows various nitrogen to phosphorous ratios from Miacomet Pond
during the summer 2016 sampling season.
Table D - below shows various nitrogen to phosphorous ratios from Miacomet Pond
during the summer 2015 sampling season.
Station Id N/P PC/PN DIN/DIP TN/TP
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
Similar to Hummock Pond observations, Total Nitrogen values are temporally variable in
both Long Pond (no MEP threshold) in 2016 versus 2015-2012 and 2010 of 0.629-0.650
versus 0.677, 1.14, 0.795, 0.94,1.75 mg/L and in Sesachacha Pond (MEP threshold <
0.60 mg/L, SES-1) 1.000 versus 0.904, 0.922, 0.669, 0.704, 0.639 mg/L. Like Hummock
and Miacomet Ponds, Long Pond and Sesachacha Ponds are poorly flushed with
Miacomet Pond not having been opened in recent years and Long Pond having a poor
hydraulic connection to Hither Creek / Madaket Harbor via Madaket Ditch. In the case
of Sesachacha Pond, the TN levels also appear to be related to the success of the
periodic openings. The similar TN levels in 2016 and 2015 (1.00 mg/L and 0.904 mg/L
respectively) are predicted from the similar Spring opening durations (5 days Spring
2015, 3 days Spring 2016) and are higher than the previous years which had better
openings and associated lower subsequent TN levels (<0.704 mg/L). It is worth noting
that the very high historic levels (1.20 mg/L) and 2010 levels were under less robust
Station Id. N/P PC/PN DIN/DIP TN/TP
(2016) organic particulate inorganic total
MP-3 33.4 7.3 2.9 26.8
MP-1 41.2 6.9 5.8 37.9
MP-2 21.8 8.6 8.8 21.8
24
opening conditions, prior to the Town’s new awareness of the importance of openings as
a pond management tool. It should be noted that TN levels in 2016 (and 2015) remain
lower than during the MEP assessment and suggest that achieving the TMDL may be
possible by refined openings, saving infrastructure costs. Additionally, it appears
nutrient related water quality is worsening as a function 2014-2016 mediocre openings.
Average TN levels in all 4 ponds are significantly higher than average values in the
“offshore” stations NAN 4 and MH4 which average 0.283 [0.297, 0.277, 0.317, 0.344,
0.302] and 0.219 [0.328, 0.254, 0.278, 0.297, 0.285] mg/L, respectively (Tables 3a, 3b,
3c, 3d, 3e,3f, Figures 1, 2). It should be noted that the average offshore TN
concentration for station MH4 is 0.295 mg/L if the 8/5/2015 sampling date (TN
concentration = 0.427 mg/L) is not included in the calculation. It appears that sample
data for that one sampling date is aberrant, which is supported by statistical analysis of
the complete data set (2010-2015).
Long Pond (no MEP threshold) 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 returned to 2013 levels in 2015 (0.697 mg/L). In 2016 TN concentrations at
station 5 declined again reaching the lowest level on record, 0.650 mg/L. This decline
from historic levels, 2010 to 2016 in TN levels at station 5 needs to be tracked closely by
the monitoring program, as MEP modeling suggests that conditions will improve
significantly in Long Pond as the landfill TN load diminishes. Similarly, Station 6 also
shows declining TN levels from historic to 2010 to 2016 samplings. Station 6 TN
concentrations in 2016 declined to the lowest on record, 0.629 mg/L even lower than
2015, 0.656 mg/L, with 2014 being 0.788 mg/L and historic levels being 0.84 mg/L.
Based on the continuing decline in TN concentrations observed in 2016 and 2015 at
both stations 5 and 6, it appears that the increase in TN levels at station 5 from 2013 to
2014 was anomalous or related to a undefined system perturbation, especially given the
long record of declining TN levels at station 6. However, continued monitoring of
stations 5 and 6 is warranted to confirm the downward trend in TN concentrations.
Overall, the monitoring results, both long term and over recent years, show a clear
decline in TN from historic to 2016 levels, with TN levels at both stations in both 2015
and 2016 being less than half of previous observations.
The long-term lowering of the TN levels, particularly at station 6, is consistent with on-
going Town activities at the landfill, as 2016, 2015, 2014 and 2013 TN levels follow a
downward trend and chlorophyll-a levels in Long Pond are significantly lower than in
2010 and 2012 and generally similar to what was measured in 2013, 2014 and 2015 but
with 2016 levels being the lowest on record. The monitoring program should continue to
track the improvements in water quality at station 5 and 6 and the Town may want to
measure nutrient water quality in the wells down gradient of the land fill to quantify the
effect the land fill actions maybe having on Long Pond and to project the potential
magnitude of the reduction in load and the time required until the full effect is realized.
As in all previous years, in Sesachacha Pond (MEP threshold <0.60 mg/L, SES-1), there
is no noticeable nutrient or chlorophyll gradient among any of the 4 Stations (Figure 13
and 14, Tables 3a,b,c,d,e,f). The well horizontally mixed nature of this salt pond results
from it only having periodic tidal exchange such that it operates more like a kettle pond
than a tidal estuary. However, it should be noted that while TN and chlorophyll-a
25
concentrations in Sesachacha Pond where generally higher in 2014 compared to 2013,
TN levels in 2015 remained high (0.904 mg/L and 0.922 mg/L respectively), which
continued through the 2016 field season. The slight rise in TN in 2016 (1.00 mg/L) is
consistent with its limited opening. It is Interesting to note that while total pigment in
2015 was higher than what was observed in 2014 (11.07 ug/L versus 6.37 ug/L
respectively), TN levels were similar in both years, and the slightly higher TN in 2016
supported a similar total pigment as 2014 (6.56 ug/L and 6.37 ug/L respectively). Given
the diverse factors which can alter pigment levels (wind, light, temperature, nutrients,
water clarity) the difference is similar to that seen in other systems throughout the
region. It should be noted that 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, 2015 and 2016 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 well above the
nitrogen threshold in the TMDL, and the 2014, 2015 and 2016 TN increase is a cause
for concern, particularly after the few prior years of much lower TN levels (~0.6 mg/L). It
appears the short duration spring openings in 2015 and 2016 are having a negative
effect on pond water quality.
Consistent with previous years monitoring results, in 2016 Madaket Harbor (MEP
threshold 0.45 mg/L, MH-1) showed a clear nitrogen gradient (and associated metrics)
from Station 1 (0.43 mg/L) in Hither Creek (which receives discharge from Long Pond
via Madaket Ditch), and is relatively poorly flushed, out to Station 2 (0.34 mg/L) in the
Harbor, with further decreases out to the off-shore Station 4 (0.22 mg/L, Figure 9 and
14, Table 3a). Similarly, in Nantucket Harbor, there is a very small nutrient gradient
from Wauwinet at the Head of the Harbor (Nan-3, 0.36 mg/L) and the more enclosed
Polpis stations out to the entrance at Stations 8 (0.28 mg/L) and 4 (0.28 mg/L). There is
also a chlorophyll gradient with the highest concentrations at the 2 Polpis Stations (5
and 6, 5.8 and 4.6 ug/L respectively) and Wauwinet basin, decreasing in the main
Harbor and out to the off-shore Station 4 (2.2 ug/L). These levels within the main open
basins are indicative of high quality habitat and nutrient related water quality.
Average 2016 [2015, 2014, 2013, 2012, 2010] TN level in Madaket Harbor (Stations 1-3,
not including Station 4, offshore) was 0.343 [0.422, 0.390, 0.404, 0.485, 0.462] mg/L,
compared to the off-shore Station 4 0.219 [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
the average of all years (2010 to 2016, 0.277 mg/L.
Average TN in Nantucket Harbor {MEP threshold = 0.35 mg/L NAN-3 and 0.355 NAN-6}
(all stations except Station 4, offshore) remain quite low averaging 0.354 mg/L
compared to 2010, 2012, 2013, 2014, 2015, with the offshore boundary station 4
averaging only 0.283 mg/L in 2016, similar to offshore Madaket Harbor station MH-4 at
0.277 mg/L (Tables 3a, 3b). It should be noted that the 2010 value includes station
NAN-8 (the cut) whereas the 2016, 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). Additionally, as specified in the nutrient TMDL developed by the
26
MassDEP based on the MEP nutrient threshold analysis, an additional monitoring station
was added in head of Nantucket Harbor (Nan-2A) to represent the water quality at the
MEP sentinel station. In 2016 the TN level at station Nan-2A was 0.415 mg/L. The
MEP TN threshold concentration were exceeded at these sentinel locations, 0.350
versus 0.415 mg/L, and for the sentinel station in Polpis Harbor (Nan-6) 0.355 mg/L
versus 2016 TN level = 0.400 mg/L.
Stream sampling in 2016 was reduced from 6 stream locations to 3 (STA. 4, 4A and 6B)
all of which discharge to Polpis Harbor. Stations 4 and 6B represent two distinct surface
water inflows to Polpis Harbor. Station 4A (selected by the Conservation Foundation) is
located up-gradient of station 4 and captures nutrient conditions prior to influence from a
network of cranberry bogs.
TN concentrations in the 2 streams to Polpis Harbor in 2016 ranged from 0.856 mg/L in
Stream 4 to 0.922 mg/L in Stream 6B (Table 3a). In spite of the high TN concentrations
in these 2 streams and the TN loads that these streams contribute to Polpis Harbor, tidal
flushing and dilution with lower concentration Nantucket Harbor waters is sufficient to
maintain TN levels in the main body of Nantucket Harbor at relatively low levels (Table
3a,b,c,d,e,f; Figure 6a). A subset of streams sampled in 2010 where sampled again in
2016 with a focus on Polpis Harbor with 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 decided to re-
establish sampling of streams discharging to this tributary sub-embayment.
Average 2016 [2015, 2014, 2013, 2012, 2010] TN concentrations in East Polpis Harbor,
0.400 [0.404, 0.378, 0.401, 0.438, 0.484] mg/L and West Polpis Harbor 0.420 [0.422,
0.389, 0.385, 0.431, 0.419] appear to have been very stable from 2016-2012. These
basins are fed by the high TN levels in Streams 4 and 6B and diffuse groundwater
inflows and support TN levels slightly higher than the levels in the main Harbor, but still
significantly lower than the levels in the streams (Table 2a, Figure 6a). It should be
noted that the two stations in Polpis Harbor (NAN-5 {Polpis west} and NAN-6 {Polpis
east}) do show essentially the same TN concentration compared to levels observed in
2015. TN levels remain above the nitrogen threshold for these basins, although total
pigment was still relatively low in 2016. Total pigment at Polpis Stations NAN-5 and
NAN-6 were slightly higher in 2016 compared to 2015 despite nearly equal TN
concentrations. Chlorophyll levels in 2015 were higher than 2014 possibly reflecting the
slightly higher TN and warmer summer conditions in 2015 compared to 2014. Overall,
TN concentrations in Nantucket Harbor were slightly lower in 2016 (0.354 mg/L)
compared to 2015 (0.381 mg/L) and slightly higher compared to summer 2014 (0.324
mg/L). As such it is important to continue summer water quality monitoring and
watershed based nutrient management and to provide a multi-year base for determining
TMDL compliance as management actions are being implemented. Evaluation of the
streams should be continued keeping stream volumetric flow and stream sampling such
that nitrogen loads to Polpis Harbor can be monitored, as input load is directly
associated with the Polpis Harbor TN levels.
Stream sampling in 2015 and 2016 included both nitrogen concentration and flow
measurements to expand the 2012, 2013, 2014 estuary sampling efforts. Stream
sampling was added due to their potential role relative to the MEP TN threshold in
Polpis Harbor (NAN-6 is considered the MEP sentinel station, with a TN threshold
27
concentration of 0.355 mg/L for restoration). Samples were collected from a total of 3
stations in 2 streams in 2016 (ST4, ST4A, ST6B) but in 2015 the same stations (ST4,
ST6B) were sampled along with ST3 to gauge TN load discharging to Polpis Harbor. In
2016, ST3 was replaced by ST4A (upgradient of ST4) because there was little flow at
ST3 in 2015 and no measureable flow in the summer of 2016 (though not checked
consistently by the Town in 2016). Stream sampling in 2016 showed high TN
concentrations at ST4 and 4A (0.856 mg/L and 0.776 mg/L respectively) but were lower
than in 2015 (ST4 in 2015 = 1.060 mg/L), based on data presented in Table 2a,b.
Interestingly, stream sampling site ST4 and ST6B were sampled once (June) in 2010
and showed TN concentrations of 1.200 and 2.139 mg/L respectively. The 2010
concentrations were consistent with the high concentrations observed in 2015 but in
2016 TN levels at both these stations (4 and 6B) were similar (0.856 mg/L and 0.922
mg/L) and lower than in 2015 or 2010. The variation in TN levels may be associated
with long-term groundwater variations and warrants continued monitoring of stream flow
and nutrient concentrations discharging to Polpis Harbor. Management of these flows
and nutrient loads may provide an added mechanism to help to achieve the MEP TN
threshold for Polpis Harbor at the sentinel station (NAN-6).
By measuring both the nutrient concentrations and the volumetric discharge the nutrient
load can be determined. Town of Nantucket staff measured the velocity of water
flowing at each sampling location in parallel with the time water quality sample collection
during the summer 2016 field season. The Town provided to CSP the critical stream
flow values (m3/d) to be coupled with the parallel measurements of total nitrogen
concentration data to calculate TN load from these streams to Polpis Harbor in summer
2016. The flow determined for each sampling day was then used to determine load for a
representative month.
Table E. 2016 flows and nitrogen and phosphorus loads determined for two streams at
sampling stations 4 and 6B. Station 4A is upgradient of station 4 in the same stream.
Measured TN Load TN Load TP Load TP Load Representative
Sample ID Date Flow Month
(m3/d)(kg/day)(kg/month)(kg/day)(kg/month)
STA4 3/16/2016 6044 3.455 107.11 0.457 14.15 March
STA4 4/20/2016 2544 1.464 43.92 0.228 6.85 April
STA4 5/17/2016 1479 1.139 35.32 0.124 3.86 May
STA4 6/14/2016 451 0.425 12.74 0.056 1.69 June
STA4 7/21/2016 0 0.000 0.00 0.000 0.00 July
STA4A 3/16/2016 734 0.405 12.55 0.009 0.29 March
STA4A 4/20/2016 361 0.199 5.96 0.004 0.12 April
STA4A 5/17/2016 183 0.115 3.56 0.003 0.08 May
STA4A 6/14/2016 214 0.163 4.90 0.004 0.12 June
STA4A 7/21/2016 31 0.029 0.90 0.001 0.03 July
STA6B 3/16/2016 452 0.215 6.67 0.013 0.40 March
STA6B 4/20/2016 449 0.176 5.27 0.013 0.38 April
STA6B 5/17/2016 1154 0.644 19.98 0.038 1.17 May
STA6B 6/14/2016 2418 3.045 91.36 0.645 19.34 June
STA6B 7/21/2016 75 0.071 2.21 0.027 0.84 July
28
Table F. 2015 flows and nitrogen loads determined for three streams. Stations 4 and
6B were also sampled in 2016.
Measured TN Load TN Load Representative
Sample ID Date Flow Month
(m3/d)(kg/day)(kg/month)
ST3 6/8/2015 259 0.301 9.0 June
ST3 7/6/2015 189 0.294 9.1 July
ST3 8/3/2015 83 0.078 2.4 August
ST3 8/31/2015 21 0.010 0.3 September
ST4 6/8/2015 2157 2.135 64.1 June
ST4 7/6/2015 999 0.981 30.4 July
ST4 8/3/2015 0 0.000 0.0 August
ST4 8/31/2015 104 0.107 3.2 September
ST6B 6/8/2015 457 0.385 11.5 June
ST6B 7/6/2015 444 0.799 24.8 July
ST6B 8/3/2015 92 0.074 2.3 August
ST6B 8/31/2015 88 0.083 2.5 September
Combining the high TN concentrations with relatively large flows measured in 2016 at
ST4 and ST6B, it is clear that a large TN load can be introduced to Polpis Harbor from
the stream sites on a monthly basis, if there is sufficient flow. It is important to note that
given some of the large loads presented for winter and spring sampling dates as
opposed to the lower loads of the year when precipitation during the summer is typically
much lower than in the winter and spring, a more robust quantification of flows and loads
is warranted given its potential influence on the sentinel station in Polpis Harbor. Given
this first approximation of the TN loads entering Polpis Harbor via streams, it would
clearly be worth continuing measuring flow and nitrogen sampling in coming years of
monitoring, particularly since flows and loads in 2016 appeared higher than in 2015.
The effect of stream inputs requires further analysis, because while flows and loads from
stream sites ST4 and 6B were measurably higher in 2016 compared to 2015, TN
concentrations at stations Nan-5 and Nan-6 in Polpis Harbor were lower in 2016
compared to 2015. Moreover, in regard to stream sampling location ST4 and ST4A
(upgradient of ST4 but selected by the Conservation Foundation to represent water
before influence of the bogs), TN load at ST4A compared to ST4 ranged from 12% to
38% of the measured load at ST4 indicating substantial “pick-up” of groundwater occurs
between these stations. Equally important, TN load from ST4 accounts for between
61% and 70% of the combined load from streams ST4 and ST6B. As such it would be
important to most accurately quantify flows and loads from ST4 and the upgradient bog
system as this surfacewater source may be the main driver of TN levels at Nan-5 and 6
in Polpis Harbor. Given these complexities, a detailed investigation of flow and loads
throughout the network of bogs up-gradient of ST4 is warranted to refine management
of nutrients entering Polpis Harbor from its associated sub-watershed. Further study
29
would be helpful to determine whether the cranberry bogs will benefit from best
management practices to limit their influence in contributing nutrients to Polpis Harbor.
As such, it may be preferable to that such an investigation be completed by the bog
owner: The Nantucket Conservation Foundation in collaboration with the bog manager
that would have detailed information on bog operating practices critical to ensure sample
timing and bog management practices are coordinated.
Additional estuarine stations (ORS-2,3,4,5,6) were added in 2015 to the sampling
stations in Nantucket Harbor and Madaket Harbor (ORS-1) specifically to monitor water
quality in the vicinity of potential sites for deployment of oyster aquaculture. A subset of
the 2015 stations (ORS-2,4,6) were sampled again in 2016. These stations had never
been sampled prior to 2015 so it is not possible to compare 2016 and 2015 results to
past years, however, 2016 and 2015 results for stations ORS-2,4,6 can serve as the
beginning of establishing a baseline for gauging changes in future years. 2016 TN
levels at ORS-2,4,6 (0.339 mg/L, 0.382 mg/L, 0.472 mg/L) were the same or a little
lower compared to 2015 (0.338 mg/L, 0.415 mg/L, 0.551 mg/L). Station concentrations
are generally consistent with the water quality from nearby long term monitoring stations.
In the future a detailed interpretation of the data collected at these stations will be
possible once more data becomes available.
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 as sufficient data has been collected (1 more
season needed). 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, particularly in Miacomet Pond and
Hummock Pond. 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.
30
Table 2a. Summary of Stream Water Quality Parameters (ST4,ST4A,ST6B) and stations associated with potential oyster aquaculture
locations (ORS,2,4,6), 2016 Nantucket Sampling Program. Station STA3 from 2015 was discontinued due to zero flow (should be
checked in out years to confirm flow) and STA4A was added to further interpret flow and load results from STA4.
Lab Avg.Avg.Avg.Avg.Avg.Avg.Avg.Avg.Avg.Avg.Avg.Avg.Avg.Avg.
Salinity PO4 TP NH4 Nox DIN DON TDN POC PON TON TN Chla Phaeo Total Pig
Date Embayment Sample ID ppt (mg/L)(mg/L)(mg/L)(mg/L)(mg/L)(mg/L)(mg/L)(mg/L)(mg/L)(mg/L)(mg/L)(ug/L)(ug/L)(ug/L)
3/16/2016 Stream to Polpis STA4 0.1 0.044 0.076 0.012 0.001 0.014 0.529 0.543 0.323 0.029 0.558 0.572 0.42 0.45 0.87
4/20/2016 Stream to Polpis STA4 0.1 0.045 0.090 0.008 0.001 0.009 0.538 0.547 0.299 0.028 0.566 0.575 0.49 0.54 1.03
5/17/2016 Stream to Polpis STA4 0.2 0.071 0.084 0.014 0.001 0.015 0.715 0.730 0.464 0.041 0.756 0.770 0.44 0.70 1.15
6/14/2016 Stream to Polpis STA4 0.1 0.064 0.125 0.022 0.004 0.026 0.862 0.888 0.552 0.054 0.915 0.942 0.40 1.15 1.55
7/21/2016 NS STA4 NS NS NS NS NS NS NS NS NS NS NS NS NS NS NS
3/16/2016 Stream to Polpis STA4A 0.1 0.007 0.013 0.012 0.001 0.013 0.515 0.528 0.259 0.023 0.539 0.552 0.11 0.45 0.55
4/20/2016 Stream to Polpis STA4A 0.1 0.005 0.012 0.010 0.002 0.012 0.512 0.524 0.295 0.027 0.539 0.551 0.28 0.46 0.74
5/17/2016 Stream to Polpis STA4A 0.1 0.006 0.014 0.014 0.000 0.014 0.584 0.597 0.523 0.031 0.615 0.628 3.89 2.26 6.15
6/14/2016 Stream to Polpis STA4A 0.0 0.010 0.019 0.022 0.006 0.028 0.704 0.733 0.310 0.030 0.734 0.763 1.10 1.85 2.94
7/21/2016 Stream to Polpis STA4A 0.1 0.016 0.027 0.023 0.010 0.032 0.856 0.888 0.441 0.050 0.906 0.938 0.20 0.92 1.13
3/16/2016 Stream to Polpis STA6B 0.0 0.021 0.028 0.013 0.003 0.016 0.434 0.450 0.309 0.026 0.460 0.476 0.15 0.40 0.55
4/20/2016 Stream to Polpis STA6B 0.0 0.018 0.028 0.010 0.002 0.012 0.361 0.373 0.257 0.019 0.379 0.392 0.39 0.57 0.96
5/17/2016 Stream to Polpis STA6B 0.0 0.025 0.033 0.014 0.002 0.015 0.516 0.531 0.351 0.028 0.543 0.558 0.38 0.69 1.07
6/14/2016 Stream to Polpis STA6B 0.0 0.118 0.267 0.023 0.008 0.031 0.891 0.922 7.398 0.338 1.229 1.259 0.35 2.01 2.36
7/21/2016 Stream to Polpis STA6B 0.0 0.173 0.361 0.020 0.008 0.028 0.604 0.632 7.724 0.317 0.921 0.949 0.005 0.39 0.40
Lab Avg.Avg.Avg.Avg.Avg.Avg.Avg.Avg.Avg.Avg.Avg.Avg.Avg.Avg.
Salinity PO4 TP NH4 Nox DIN DON TDN POC PON TON TN Chla Phaeo Total Pig
Date Embayment Sample ID ppt (mg/L)(mg/L)(mg/L)(mg/L)(mg/L)(mg/L)(mg/L)(mg/L)(mg/L)(mg/L)(mg/L)(ug/L)(ug/L)(ug/L)
5/12/2016 Old North Wharf - Oyster ORS2 31.5 0.006 NS 0.004 0.000 0.004 0.144 0.148 0.222 0.036 0.180 0.184 0.61 0.38 0.99
6/27/2016 Old North Wharf - Oyster ORS2 32.0 0.014 NS 0.008 0.009 0.017 0.195 0.213 0.430 0.074 0.269 0.287 1.57 0.73 2.30
7/11/2016 Old North Wharf - Oyster OR2 31.1 0.018 NS 0.007 0.003 0.010 0.248 0.258 0.589 0.104 0.352 0.362 3.66 0.66 4.32
8/25/2016 Old North Wharf - Oyster ORS2 32.1 0.014 NS 0.004 0.002 0.006 0.098 0.104 0.478 0.081 0.178 0.184 1.43 0.55 1.98
9/20/2016 Old North Wharf - Oyster ORS2 32.0 0.021 NS 0.006 0.007 0.013 0.425 0.438 0.331 0.087 0.512 0.525 0.59 0.60 1.19
5/12/2016 Shimmo - Oyster ORS4 30.8 0.008 NS 0.004 0.008 0.012 0.147 0.159 0.252 0.038 0.185 0.197 0.48 0.32 0.80
6/27/2016 Shimmo - Oyster ORS4 31.6 0.016 NS 0.012 0.001 0.013 0.202 0.214 0.836 0.162 0.364 0.377 3.83 0.82 4.65
7/11/2016 Shimmo - Oyster OR4 29.7 0.022 NS 0.012 0.006 0.018 0.289 0.307 0.647 0.117 0.406 0.424 1.35 1.16 2.51
8/25/2016 Shimmo - Oyster ORS4 31.5 0.019 NS 0.008 0.003 0.010 0.128 0.138 0.727 0.125 0.253 0.263 1.50 1.41 2.91
8/25/2016 Shimmo - Oyster ORS4 31.4 0.019 NS 0.012 0.002 0.014 0.139 0.153 0.656 0.112 0.251 0.265 1.14 1.25 2.40
9/20/2016 Shimmo - Oyster ORS4 31.4 0.019 NS 0.007 0.006 0.013 0.287 0.300 0.840 0.165 0.452 0.465 3.13 0.52 3.64
5/12/2016 Polpis - Oyster ORS6 30.5 0.008 NS 0.005 0.000 0.005 0.157 0.162 0.337 0.050 0.207 0.212 0.59 0.64 1.23
6/27/2016 Polpis - Oyster ORS6 32.0 0.024 NS 0.008 0.001 0.009 0.280 0.289 0.566 0.101 0.381 0.390 1.80 1.05 2.86
7/11/2016 Polpis - Oyster OR6 30.9 0.021 NS 0.061 0.002 0.063 0.298 0.360 0.769 0.137 0.435 0.498 2.96 1.43 4.39
8/25/2016 Polpis - Oyster ORS6 32.1 0.027 NS 0.018 0.002 0.020 0.173 0.194 ----0.844 --4.49 4.61 9.09
9/20/2016 Polpis - Oyster ORS6 31.4 0.026 NS 0.006 0.006 0.011 0.334 0.345 1.947 0.185 0.519 0.530 3.01 0.36 3.37
31
Table 2b. 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
32
Trophic State of the Estuaries of Nantucket Island
The Trophic State of an estuary is a quantitative indicator of its nutrient related
ecological health and is based on key ecological metrics: concentrations of inorganic
and organic Nitrogen, water clarity (Secchi Depth), lowest measured concentrations of
Dissolved Oxygen (average of lowest 20% of measurements), and Chlorophyll-a
pigments (surrogate for phytoplankton biomass/blooms). Nutrient related trophic health
scales generally range from Oligotrophic (healthy-low nutrient) to Mesotrophic (showing
some signs of deterioration of health due to nutrient enrichment) to Eutrophic (habitats
significantly impaired and degraded, high levels of nutrients and organic matter and
community shifts). The Trophic Health Index Score used here is a standard numerical
scale based on criteria for open water embayments and uses the above mentioned
measured parameters to create a habitat quality scale (Howes et al. 1999,
http://www.savebuzzardsbay.org). For the estuaries within the Town of Nantucket, a
trophic index score was calculated for each sampling location for each year (2010 and
2012- 2016) using the summer monitoring results. The Index scores were calculated in
2 ways, one which included the low dissolved oxygen for each year in the index ("with
DO", Table 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 (i.e. missing periodic low oxygen events). This
bias was found in the previous analysis of the 2010 dataset, as well as for other
estuaries in s.e. Massachusetts. However, this is not always the case and there was no
substantive difference between the "with DO" and "without DO" Index scores based on
the 2013 and 2014 data and again in 2016, 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 19-23 show the distribution of Health
Status throughout each estuary based on each of the 6 years of monitoring (2010, 2012,
2013, 2014, 2015, 2016). For the location maps, only the “with DO” index is shown as in
3 of the past 4 years the inclusion of DO made no substantive difference in the index
value and in 2015 the difference was minor. Therefore, the Index maps are only shown
for the “with DO” index, as it is then comparable to other estuaries in the region and is
yielding an accurate representation of Trophic Status. 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:
33
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 6 years of monitoring. Although change at some sites was
observed, change was gradual and large inter-annual changes were typically related to
major management actions. This relative stability is typical as nutrient related health
does not generally change rapidly unless a significant alteration has occurred to the
watershed nitrogen loading or to tidal flushing of a basin (e.g. Hummock Pond).
However, 3 systems do appear to show a potential shift in nitrogen related health over
the past 6 years, Hither Creek, lower Hummock Pond and Long 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 in 2016 continued to support a high level of nutrient related
water quality. It has been the more enclosed basins of Hither Creek and Long Pond with
their reduced tidal flushing that have nitrogen impairment problems. Water quality
generally changes gradually, unless there has been a major change in loading or
flushing. Within the Madaket Harbor/Long Pond watershed there has been a significant
change in the nitrogen sourced at the Town Landfill. The Landfill has recently been
undergoing management actions that reduce nitrogen loading to the groundwater, hence
to upper Long Pond. It appears that the long-term gradual reduction in TN levels within
the upper portions of this complex estuary is consistent with a lowering of watershed
nitrogen loading. Over the 6 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 19). Hither Creek
is clearly nitrogen enriched and showing continuing impairment based on a variety of
parameters. However, over the past 6 years the Index indicates that this basin has
improved slightly each year, going from fair-poor water quality and improving in a step-
wise manner to moderate water quality since 2014. The 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 can receive
low quality waters on the ebb tide from Hither Creek and that can modify water quality at
this nearshore location (e.g 2010). But with improvements in the water quality in Hither
Creek, its effect on water quality at Station 2 in nearshore Madaket Harbor has been
insufficient to effect the Harbor waters, which have maintained high quality status since
2012. The offshore sites (3 & 4) support high quality waters resulting from low nitrogen
inputs and very high rates of water exchange. The 6 year positive trend in health index
is at least partially the result of the reduced loading from the landfill to upper Long Pond
and an improvement in the ebbing waters through Madaket Ditch. This trend is
34
consistent with the upper basin feeding Madaket Ditch In 2014-2016 the previously
observed gradient in water quality metrics between the 2 Long Pond stations diminished
significantly, to the point where concern over a tidal restriction is lessened. While a
further analysis of the mechanism underlying this periodic gradient would be useful, it is
not needed at this time, tracking the phenomenon through the on-going monitoring
program should be sufficient. If the improvement in Hither Creek 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, additional analysis is required
to determine if landfill activities will be sufficient to meet the TMDL for Long Pond (see
below). Additional study to clarify the drivers of the improvement (controllable such as
the landfill improvements or fertilizer management) will further assist in determining the
magnitude of septic system management as posited through the MEP analysis.
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
19). Unlike Madaket Harbor which is marine, Long Pond is a brackish water system
resulting from mixing of groundwater inflows and salt water entering through its
restricted tidal channel. Long Pond’s Bay Health scores for both stations (5 & 6) in the 6
years of monitoring (2010, 2012-2016) 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, appears to be reducing the nitrogen load from this
source and the observed lowering of TN levels in Long Pond is temporally consistent
with the landfill improvements. While still small, the water quality Index for Long Pond is
starting to improve in response to the lower TN levels although the basin remains
impaired. TN levels in 2015 and 2016 were almost half that of historical and 2010
measurements. While continued monitoring will determine the level of improvement, it
does appear that the reduction in N loading may be occurring with beneficial effects.
However, even if TN levels stabilize at 2015 levels, the TN is still too high for restoration
and the basin still supports 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 2012-2016 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 2017 sampling
season 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 20). 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,
35
SMAST station 2A (the official MEP sentinel station for which the nitrogen threshold was
established, refer to Figure 2) was added (TN 0.399 mg/L) to the monitoring along with
station 3 in order to meet TMDL compliance monitoring criteria. Summer 2016 showed
similar water quality in this basin as 2014 which showed improved chlorophyll-a and TN
levels versus prior years. The main driver of the 2015 water quality was a phytoplankton
bloom in the upper Harbor, which was relatively large for Nantucket Harbor but only
moderate for more enriched estuaries in the region. While it is unclear if blooms will
become more commonplace in the future, the levels in 2016 reflected more historic
conditions, but this needs to be tracked. However, other activities associated with the
Harbor (additional sewer hookups, jetty improvement and oyster aquaculture) should
result in even lower TN and chlorophyll levels and reduce the likelihood of large
phytoplankton blooms in the future.
A similar pattern was seen in the enclosed sub-basins of Polpis Harbor (East and West)
as in the main basins of Nantucket Harbor. Polpis Harbor basins which after showing
moderate impairment in 2010 and 2012 have been showing only low to moderate
impairment in recent years, suggesting some improvement over historic conditions. As
in Wauwinet, Polpis Harbor showed 2016 TN levels similar to 2010, 2012 and 2015,
slightly higher than 2013 and 2014. This variation makes continued monitoring essential
to clarify any trends in water quality. Polpis Harbor did not show a phytoplankton bloom
in 2015 and supported only moderate-low phytoplankton biomass in 2015 and 2016 (<6
ug/L) and appears to have attained moderate-high water quality status from moderate
status in 2010 and 2012. While the overall Nantucket Harbor System is generally
supporting high quality waters, the variability in the index in Wauwinet and Polpis basins
should be monitored to ascertain their long-term health and to determine the
effectiveness of restoration effort by the Town as it continues to move forward to meet
the MassDEP TMDL for this system. Overall, Nantucket Harbor appears to be relatively
stable from year to year 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. Equally
important, although variable, it appears that slight positive changes have been occurring
in recent years.
Sesachacha Pond
Sesachacha Pond is a closed coastal salt pond that has its water quality managed by
periodically breaching the barrier beach to open the basin to tidal exchange with the
adjacent Atlantic Ocean waters. This management action serves to flush out nutrients
and organic matter on the ebb tides and receive saline waters on the flood tides.
Sesachacha Pond was evaluated under the Massachusetts Estuaries Project and a
nitrogen threshold (0.60 mg/L) was established for restoration of this system.
Additionally, the MEP analysis recommended an additional mid-summertime opening 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 return
to historic levels of TN, ~0.9 mg/L. The 2016 sampling showed that the trend has
36
continued with TN levels of 1.00 mg/L, close to the historic 1.20 mg/L levels associated
with significantly impaired conditions. It is likely that these changes relate to the quality
of the pre-summer opening. Given the 2010-2013 period when robust openings
occurred, it appears that a solid opening program has the capability to improve the water
quality metrics pond-wide to levels near the TMDL nitrogen threshold.
Based upon the Index alone, changes in water quality in Sesachacha Pond over the
2010-2013 period were stabilized at moderate impairment of this estuary, with the past 3
seasons seeing a significant trend toward poor water quality conditions (Figure 21) as
TN levels have risen. 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 and 2016 data underscores the reversal of improvement with phytoplankton
biomass (as chlorophyll) averaging >10 ug/L at all stations over the summer of 2015 and
6-10 ug/L in 2016, consistent with nitrogen enrichment. The high chlorophyll values are
consistent with the high TN values in 2014-2016. It appears that like other periodically
opened ponds, the quality of the opening (amount of water exchanged) controls the level
of water quality in the following months. Fortunately, the data indicate that attaining
pond openings of the quality of 2012 and 2013 (done under Town supervision) in the
future may be sufficient to attain the TMDL for this system. A closer examination of the
opening protocol and the linkage to resultant water quality is needed for management of
this system.
Hummock Pond
Hummock Pond is a closed coastal salt pond that is only periodically opened to the
ocean to flush out nutrients and organic matter on the ebb tide and receive low nutrient
saline waters on the flood tide. Creating sustained openings that are sufficient to allow
exchange of tidal waters for more than 4-5 days has been difficult for this system due to
its location on the coast and the large amount of sand migration in the coastal zone
which can rapidly reseal the inlet.
Hummock Pond is opened at a sufficient frequency to sustain salinity levels in the 4-8
ppt range, with only small inter-annual differences (2012 slightly higher than 2010). The
pond supports a small but clear salinity gradient from Station 1 nearest the ocean to
Station 7 in the uppermost basin (Head of Hummock). The present non-tidal state and
watershed nutrient inputs have resulted in moderate to poor nutrient related water
quality throughout the pond, with poor water quality conditions the present norm (2005-
2007, 2010, 2012, 2013, 2014, 2015). Unfortunately, in 2016 the pond appears to have
had lower water quality in its upper and mid reaches than in previous years, although the
lower basin did not show this inter-annual variation. There is a small gradient in water
quality with moderate to poor conditions near the ocean and poor conditions in the
uppermost basins (Figure 22). This gradient stems from the periodic openings and
over-wash events. The uppermost basin, Station 7, is approaching fresh/brackish
conditions (4 ppt) and is currently supporting mainly freshwater plant and animal
habitats. This basin is particularly eutrophic with phytoplankton blooms periodically
exceeding 70 ug/L (offshore waters are ~2 ug/L), although 2016 showed levels <16
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
37
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. Unfortunately, this pattern was
not seen in the 2016 water quality data, which showed some decline in the upper and
mid reaches. 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.
Miacomet Pond
Miacomet Pond is a closed coastal salt pond that is rarely (once in the past ten years)
opened to the ocean to flush out nutrients and organic matter on the ebb tide and
receive low nutrient saline waters on the flood tide. As a result of the lack of tidal flow
and annual groundwater inputs, the pond is presently freshwater, with salinity levels in
each of the 5 years of monitoring of <0.5 ppt, reaching a low of 0.1 ppt in 2015 and
2016. The present non-tidal state and extent of watershed nutrient inputs has resulted
in a decline in nutrient related water quality throughout the pond for both nitrogen and
phosphorus, with poor water quality conditions the present norm (Figure 23). This can
be seen, for example, in the high chlorophyll levels (2010: 12-50 ug/L); 2012: 10-20
ug/L; 2013: 20-26 ug/L; 2014: 23-70 ug/L; 2015: 38-53 ug/L) several times the levels
found in the high quality basins of Nantucket and Madaket Harbors with 2016 continuing
being about average (12-18 ug/L), but lower than 2015 where the highest chlorophyll a
levels throughout the pond were observed over the period of record. It appears that
2015 had high chlorophyll levels in several of Nantucket’s estuaries, with conditions
returning to average levels in 2016. All of the metrics for Miacomet Pond are consistent
with a nutrient impaired basin. However, as the freshening of this basin has become
complete and sustained, it likely will have to be managed as a transitional freshwater
system and will need to be reassessed as such. As salt ponds freshen and become
fresh ponds the nutrient causing eutrophication can shift to phosphorus from nitrogen or
become both nitrogen and phosphorus (seasonally varying nutrient limitation). Since
Miacomet Pond may have storm 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.
38
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. It would be
prudent to begin development of a management plan that takes into account not only the
nutrient related impairment of Miacomet Pond, but also accommodates the likely shifting
between fresh and salt water over the long term.
Recommendations for Future Monitoring (2017)
(1) As mentioned in previous years summaries of estuarine water quality across
Nantucket, due to the critical importance of dissolved oxygen to the ecological health of
an estuarine basin, additional data should be collected using high frequency automated
sensors when the low frequency sampling of the monitoring program suggests that a
problem may exist in a specific basin. At this point, Polpis Harbor and Wauwinet basin
in Nantucket Harbor should be considered for this analysis at some time in the future
(e.g. summer 2017) as well as Hummock Pond and Miacomet Pond. It may also be
timely to complete a higher level assessment of Miacomet Pond as that large “salt pond”
has been transitioning to a freshwater ecosystem and has been showing consistently
poor water quality and low trophic status indicative of an impaired habitat. However,
procedural steps should also be implemented to strengthen the oxygen data base from
the on-going monitoring program. In addition, Long Pond appears to be experiencing a
lowering of its nitrogen levels over the past decade, since the MEP full assessment of
ecological health. At present, it is not known how much Town activities at the Landfill
have lowered the annual nitrogen input from this source or how long it will take for the
full reduction to occur. In addition, the extent of ecological improvement in Long Pond
has not been assessed toward meeting the restoration targets under the Clean Water
Act, although the lowering of nitrogen levels is a very positive result.
Approaches to address these 2 issues are:
a) Deploying in situ oxygen meters (sondes) on the bottom of specific
estuaries at several strategic locations for the summer months when periodic
hypoxic or anoxic events in bottom waters can occur.
b) Long Pond is 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 when
completed. The monitoring results from 2012 - 2016 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 levels in 2016 continued to show a slight decline from
2015 and 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
which dropped again to 0.649 mg/L}, station 6 {0.788 dropped to 0.656 and
dropped again to 0.629 mg/L}). At present TN levels are the lowest on
record. The landfill analysis would allow prediction of how low TN levels
39
should decline and should help guide the timing of an ecological assessment
focusing on if TMDL compliance has been achieved.
(2) Results from stream stations discharging to Nantucket Harbor (specifically Polpis Harbor)
for which sampling was conducted only in 2015 and 2016 indicated that the nitrogen load from
these streams can be significant relative to Polpis Harbor, but that it was highly seasonal due
to lower stream flow volumes in summer. With increasing interest in lowering TN
concentrations in Polpis Harbor to meet the MEP established TN threshold, it is appropriate to
extend stream sampling into the 2017 sampling season given the high concentrations of total
nitrogen observed in 2016 and 2015 that are discharging to this tributary sub-embayment. To
insure the utility of these data, it is critical that parallel sampling of stream flow and nitrogen
concentration continue to be the protocol to allow determination of the nitrogen load discharged
to the Harbor from each stream watershed and to gauge the degree to which the loads from
these streams contribute to the TN concentration at the sentinel station in Polpis Harbor. The
effect of stream inputs to Polpis Harbor warrants continued study because flows and loads from
stream sites ST4 and 6B were measurably higher in 2016 compared to 2015, and the
relationship of stream discharge to TN levels in Polpis Harbor remains unclear. Moreover, in
regard to stream sampling location ST4 and ST4A, TN load at ST4A compared to ST4 ranged
from ~12% to 38% of the measured load at ST4, although the average TN concentrations were
fairly similar (0.856 versus 0.776 mg/L). It is clear that there is significant “pick-up” of flow and
load to the stream occurring between the upper and lower station, which dominates the stream
discharge to the Harbor. The source of this nitrogen has not yet been assessed. The initial
data also indicates that TN load from ST4 accounts for 61% to 70% of the combined load
from streams ST4 and ST6B. As such it would be important to determine the watershed areas
contributing flow and load to ST4 to a lesser extent from the upgradient bog system relative to
reducing loads to Polpis Harbor. A more detailed investigation is warranted in collaboration
with the bog owner.
(3) Miacomet continues to show poor trophic conditions, high TN concentrations through its
basins (stations 1, 2, and 3 in 2016: 0.772, 0.669, 0.783 mg/L, respectively). Although TN
levels were lower in 2016 than in 2015 they are still indicative of a highly enriched condition, as
also indicated by the high total pigment concentrations (CHLA + pheophytin) in 2016. In light of
yet another year of poor water quality in Miacomet Pond, nitrogen and phosphorus budgets
should be developed for Miacomet Pond and a quantitative analysis of N versus P as the
driving nutrient of eutrophication. This information can be used to directly support development
of management options for improving the pond’s health. Results of the Miacomet
Comprehensive Management Plan should be considered in advance of summer 2017 sampling
along with input from public meetings to supposedly being held this winter 2017. Additionally,
results of a 604b study prepared by Water Resources Services in conjunction with the Town of
Nantucket, Nantucket Pond Coalition and Nantucket Land Council to address N/P limitation
using groundwater wells should be factored into the sampling program for summer 2017.
These studies may clarify the extent of N vs. P limitation but detailed nitrogen and phosphorous
budgets may still be needed to develop or refine management strategies for this system.
(4) Pond Openings and Linkage to Water Quality. Hummock Pond appears to have its
nutrient related health significantly controlled by the success of its periodic openings. As
a result, the Town and Nantucket Land Council undertook an analysis of openings in
2013-2014 to refine the opening protocol and gauge its effectiveness. Critical elements
of the protocol were described in a technical memorandum developed by the Coastal
Systems Program which summarized two openings that were monitored to gauge
40
effectiveness. The opening protocol developed from this detailed work should continue
to be rigorously implemented as monitoring clearly shows that if specific conditions are
taken into consideration during a given opening, the ensuing opening tends to be
effective and have a clear positive impact on water quality. To date Hummock Pond
water quality has significantly improved under the revised opening protocol by the Town.
Monitoring of the openings should be continued to evaluate the need for a mid-summer
opening (as was recommended for the Sesachacha Pond system) in this system and to
improve the present protocol and to set metrics for evaluating a “successful” opening in
real time. Monitoring should include wind and tidal conditions during a given opening,
pond water level before during and after the opening, water quality before opening and
after closure, size of opening {depth and width} and number of days that tidal flows (in
and out) occurred. As more data becomes available, a simplified approach will be
developed for predicting the subsequent TN level at the sentinel station for management
purposes.
Similarly, the opening protocol should be used 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 it appeared that the improvement
was directly related to the effectiveness of openings and subsequent tidal exchange, as
loads into the pond are low and relatively stable. However, this earlier improvement has
not continued in subsequent years with TN levels in 2014, 2015 and 2016 (0.919, 0.918
and 1.01 mg/L respectively) rising nearly to historic levels. It should be noted that the
TN levels in 2010,2012,2013 (0.684, 0.678, 0.714 mg/L respectively) were approaching
the TMDL compliance level of 0.60 mg/L for restoration. Details of the openings in
2014, 2015 and 2016 should be compiled and compared to the openings completed in
2010, 2012 and 2013 in order to ascertain (if possible) the difference between openings
and any improvements to the protocol for Sesachacha Pond openings. It should be
noted that timing and construction of a proper pond opening is a difficult task to
accomplish successfully, especially through a large barrier beach like that separating
Sesachacha Pond from the ocean waters. The concept is to first document what has
worked and what has not to help make the efforts by the Town more beneficial. Future
openings in 2017 should be monitored, as for Hummock Pond, to build a database of the
details of an effective opening in both Sesachacha Pond (and Hummock Pond). The
data base will serve to strengthen and refine the Ponds Opening Protocol with the goal
of making future openings more beneficial to the associated pond’s water quality and
producing simplified approaches to reduce the effort required for a successful opening..
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
41
support from Land Council staff. It is through the dedication of these groups and the efforts of
other environmental stewards in the Town of Nantucket that Nantucket’s estuaries are being
protected and in some cases already moving toward restoration.
42
Table 3a. Summary of Water Quality Parameters, 2016 Nantucket Sampling Program. Values are Station Averages of all sampling events,
May-September for sampling sites. Station NAN6, NAN 6C are duplicate samples (C = compliance sample) and represent an MEP sentinel
location for monitoring in Nantucket Harbor. This also applies to Station NAN-2A and 2AC, however, NAN-2A is in a new station and in a
different location than NAN-2. It should be noted that TP was only evaluated in the stream sites, Hummock Pond and Miacomet Pond because
of the expected low salinity values in those closed pond and the possibility that the Miacomet system maybe phosphorous limited rather than
nitrogen limited. Further study should investigate the possibility of P-limitation and TP paired with salinity should continue to be monitored during
the summer 2017 field season.
20% Low 20% Low
Secchi Secchi Field Field Avg.Avg.Avg.Avg.Avg.Avg.Avg.Avg.Avg.Avg.Avg.Avg.
Embayment Station ID average Depth DO DO Salinity PO4 TP NH4 Nox DIN DON TDN POC PON TON TN Total Pig
(2016)(meters)% of WC Sat Sat (ppt)(mg/L)(mg/L)(mg/L)(mg/L)(mg/L)(mg/L)(mg/L)(mg/L)(mg/L)(mg/L)(mg/L)(ug/L)
(mg/L)(% sat)
Hummock Pond HUM7 1.26 0.36 1.97 23%4.10 0.06 0.058 0.0550 0.0337 0.0887 0.39 0.48 1.08 0.19 0.58 0.67 5.91
Hummock Pond HUM8 0.44 0.35 4.18 49%4.70 0.06 NS 0.0393 0.0078 0.0471 0.62 0.67 2.94 0.52 1.15 1.19 15.71
Hummock Pond HUM5 0.62 0.30 2.93 34%6.40 0.03 0.054 0.0492 0.0029 0.0521 0.50 0.55 1.88 0.32 0.82 0.87 10.11
Hummock Pond HUM3 0.87 0.49 6.99 83%7.24 0.02 0.054 0.0042 0.0015 0.0056 0.45 0.45 1.20 0.20 0.65 0.65 5.34
Hummock Pond HUM1 0.92 0.45 6.16 75%8.17 0.02 0.050 0.0083 0.0024 0.0107 0.38 0.39 1.21 0.20 0.58 0.59 4.81
Long Pond LONG6 0.68 0.73 4.21 56%14.80 0.01 NS 0.0148 0.0044 0.0272 0.37 0.40 1.34 0.22 0.60 0.63 5.90
Long Pond LONG5 0.78 0.77 2.48 32%10.93 NS NS 0.0020 0.0021 0.0041 0.33 0.34 1.88 0.31 0.65 0.65 5.74
Madaket Harbor MH1C 1.75 0.76 4.27 62%27.32 0.03 NS 0.0164 0.0113 0.0277 0.27 0.32 0.79 0.15 0.41 0.44 3.68
Madaket Harbor MH1 1.63 0.82 3.38 46%26.64 0.03 NS 0.0359 0.0146 0.0505 0.27 0.32 0.71 0.12 0.38 0.43 3.50
Madaket Harbor MH2 1.60 1.00 4.94 69%29.31 0.01 NS 0.0144 0.0062 0.0206 0.21 0.23 0.60 0.10 0.32 0.34 2.56
Madaket Harbor MH3 2.14 1.00 5.31 72%31.36 0.01 NS 0.0094 0.0037 0.0132 0.18 0.20 0.47 0.07 0.25 0.26 1.71
Madaket Harbor MH4 3.06 0.79 5.92 80%31.92 0.01 NS 0.0077 0.0040 0.0116 0.16 0.17 0.33 0.05 0.21 0.22 1.50
Miacomet Pond MP3 0.93 0.55 5.24 59%0.10 0.01 0.065 0.0103 0.0077 0.0180 0.39 0.38 2.33 0.37 0.76 0.78 17.75
Miacomet Pond MP1 1.06 0.57 5.09 59%0.10 0.00 0.045 0.0063 0.0049 0.0112 0.41 0.42 2.08 0.35 0.76 0.77 12.28
Miacomet Pond MP2 1.33 0.54 4.86 57%0.10 NS 0.068 0.0083 0.0086 0.0169 0.38 0.40 2.00 0.27 1.27 0.67 12.26
Nantucket Harbor NAN3 2.34 0.46 4.61 66%31.73 0.02 NS 0.0081 0.0034 0.0115 0.23 0.24 0.72 0.11 0.34 0.36 3.79
Nantucket Harbor NAN6 1.98 0.80 4.81 69%31.23 0.02 NS 0.0101 0.0034 0.0135 0.24 0.25 0.92 0.12 0.39 0.37 4.61
Nantucket Harbor NAN6C 2.15 0.78 4.97 71%31.52 0.02 NS 0.0091 0.0021 0.0112 0.26 0.27 1.27 0.16 0.42 0.43 4.69
Nantucket Harbor NAN5 1.68 0.84 4.53 65%31.07 0.02 NS 0.0073 0.0040 0.0112 0.24 0.25 1.11 0.17 0.41 0.42 5.80
Nantucket Harbor NAN2 2.14 0.43 5.11 73%31.81 0.02 NS 0.0089 0.0026 0.0115 0.20 0.22 0.59 0.10 0.30 0.31 2.98
Nantucket Harbor NAN2A 2.34 0.47 4.37 62%31.97 0.02 NS 0.0090 0.0030 0.0121 0.25 0.27 0.92 0.13 0.39 0.40 4.99
Nantucket Harbor NAN2AC 2.30 0.56 4.26 60%32.02 0.03 NS 0.0085 0.0023 0.0108 0.25 0.26 1.13 0.17 0.42 0.43 5.29
Nantucket Harbor NAN7 1.91 0.81 5.12 73%31.71 0.02 NS 0.0072 0.0030 0.0102 0.18 0.19 0.87 0.11 0.29 0.30 3.74
Nantucket Harbor NAN1 2.31 0.64 5.14 73%31.90 0.02 NS 0.0075 0.0035 0.0110 0.23 0.24 0.43 0.08 0.31 0.32 2.02
Nantucket Harbor NAN8N 1.30 1.00 4.73 0.66 31.65 0.02 NS 0.0076 0.0045 0.0120 0.20 0.21 0.41 0.07 0.26 0.28 1.72
Nantucket Harbor NAN4 2.44 0.50 5.49 77%32.04 0.02 NS 0.0078 0.0031 0.0108 0.20 0.22 0.45 0.07 0.27 0.28 2.23
Nantucket Hrb. Stream Site STA4 0.28 0.46 5.48 53%0.15 0.07 0.105 0.0178 0.0027 0.0206 0.79 0.81 0.51 0.05 0.84 0.86 1.35
Nantucket Hrb. Stream Site STA4A 0.20 1.00 2.45 23%0.07 0.01 0.020 0.0194 0.0052 0.0246 0.71 0.74 0.42 0.04 0.75 0.78 3.41
Nantucket Hrb. Stream Site STA6B 0.20 0.78 4.72 47%0.00 0.11 0.220 0.0188 0.0059 0.0247 0.67 0.69 5.16 0.23 0.90 0.92 1.28
Sesachacha Pond SESA3 ND 0.23 5.90 74%11.59 0.22 NS 0.1232 0.0053 0.1285 0.45 0.57 3.43 0.43 0.90 1.01 6.46
Sesachacha Pond SESA2 ND 0.16 5.76 73%11.57 0.22 NS 0.1265 0.0061 0.1326 0.46 0.59 3.35 0.41 0.89 0.99 6.72
Sesachacha Pond SESA4 ND 0.21 5.94 74%11.59 0.22 NS 0.1165 0.0063 0.1228 0.47 0.59 3.35 0.42 0.91 1.00 6.18
Sesachacha Pond SESA1 0.79 0.15 5.58 70%11.55 0.21 NS 0.1012 0.0061 0.1072 0.46 0.57 3.55 0.44 0.90 1.01 6.85
Sesachacha Pond SESA1C 0.75 0.14 ND ND 11.30 0.17 NS 0.0014 0.0013 0.0027 0.48 0.49 3.13 0.39 0.88 0.88 10.22
OLD NORTH WHARF - Oyster ORS2 1.45 1.00 4.75 67%31.80 0.02 NS 0.0061 0.0054 0.0115 0.24 0.25 0.46 0.09 0.33 0.34 2.45
SHIMMO - Oyster ORS4 1.09 0.88 2.53 35%31.04 0.02 NS 0.0102 0.0038 0.0140 0.23 0.24 0.75 0.14 0.37 0.38 3.36
POLPIS - Oyster ORS6 1.14 0.92 4.46 63%31.60 0.02 NS 0.0232 0.0027 0.0259 0.27 0.30 1.09 0.14 0.54 0.47 4.93
43
Table 3b. Summary of Water Quality Parameters, 2015 Nantucket Sampling Program. Values are Station Averages of all sampling events,
May-September for sampling sites. It should be noted that TP was only evaluated in Miacomet Pond because of the expected low salinity values
in that closed pond and the possibility that the system maybe phosphorous limited rather than nitrogen limited.
2015 Seccchi Secchi 20% Low 20% Low
Sample ID Depth Depth as Field DO DO Sat Salinity PO4 TP NH4 Nox DIN DON TDN POC PON TON TN Total Pig
(meters)% of WC (mg/L)(%)ppt (mg/L)(mg/L)(mg/L)(mg/L)(mg/L)(mg/L)(mg/L)(mg/L)(mg/L)(mg/L)(mg/L)(ug/L)
HUM1 1.50 48%7.13 83%7.43 0.009 --0.004 0.003 0.007 0.350 0.357 1.097 0.182 0.532 0.539 10.50
HUM3 1.50 61%6.82 75%7.11 0.012 --0.005 0.006 0.011 0.402 0.413 1.236 0.209 0.610 0.622 9.41
HUM5 1.00 57%6.87 79%5.45 0.019 --0.005 0.003 0.008 0.359 0.366 1.206 0.192 0.550 0.558 8.58
HUM7 1.30 49%5.65 87%3.33 0.101 --0.089 0.030 0.119 0.349 0.468 0.996 0.154 0.502 0.621 7.07
HUM8 0.70 90%7.13 95%3.90 0.059 --0.005 0.011 0.016 0.366 0.381 1.230 0.195 0.560 0.576 12.82
LONG5 0.70 86%6.60 85%16.02 0.020 --0.012 0.004 0.016 0.378 0.395 2.025 0.302 0.681 0.697 8.95
LONG6 0.60 76%5.78 73%16.01 0.025 --0.006 0.002 0.008 0.369 0.377 1.619 0.280 0.649 0.656 10.78
MH1 1.80 77%4.88 68%29.28 0.021 --0.019 0.006 0.025 0.379 0.404 0.652 0.120 0.499 0.524 4.82
MH2 1.78 100%5.56 78%31.76 0.010 --0.012 0.030 0.042 0.289 0.331 0.482 0.088 0.376 0.418 3.07
MH3 2.40 97%6.57 90%32.00 0.010 --0.005 0.001 0.006 0.236 0.242 0.461 0.082 0.318 0.324 3.00
MH4 2.90 63%6.70 91%32.13 0.015 --0.006 0.002 0.008 0.269 0.277 0.301 0.051 0.321 0.328 2.54
MP1 0.90 50%6.94 83%0.10 0.008 0.084 0.025 0.013 0.038 0.592 0.630 3.870 0.666 1.259 1.297 46.52
MP2 0.70 32%6.10 82%0.11 0.009 0.090 0.042 0.011 0.053 0.593 0.646 3.726 0.671 1.264 1.318 53.40
MP3 1.40 54%7.91 91%0.10 0.017 0.136 0.021 0.057 0.077 0.396 0.473 2.878 0.518 0.914 0.992 37.91
NAN1 ND 62%6.29 88%32.13 0.024 --0.010 0.002 0.012 0.246 0.258 0.437 0.072 0.318 0.330 3.84
NAN2 2.65 49%5.95 85%32.25 0.019 --0.018 0.001 0.019 0.272 0.291 0.474 0.084 0.355 0.374 4.33
NAN3 1.45 27%5.89 86%32.37 0.026 --0.022 0.002 0.024 0.278 0.302 0.716 0.134 0.412 0.436 7.16
NAN4 3.80 65%6.58 91%32.14 0.019 --0.010 0.001 0.011 0.219 0.230 0.357 0.066 0.286 0.297 3.58
NAN5 1.65 85%5.32 76%31.92 0.021 --0.018 0.001 0.019 0.296 0.316 0.578 0.107 0.403 0.422 3.86
NAN6 1.95 73%5.64 81%31.94 0.019 --0.014 0.001 0.015 0.282 0.297 0.555 0.107 0.389 0.404 4.39
NAN7 1.45 76%6.20 86%32.00 0.019 --0.013 0.002 0.015 0.270 0.285 0.628 0.105 0.375 0.390 3.68
NAN8N 1.00 96%5.65 81%31.97 0.016 --0.007 0.002 0.009 0.227 0.236 0.435 0.077 0.304 0.313 3.08
SESA1 0.60 20%7.06 88%11.26 0.202 --0.006 0.003 0.008 0.479 0.487 3.193 0.431 0.910 0.918 11.45
SESA2 0.60 14%6.55 82%11.27 0.202 --0.003 0.002 0.005 0.448 0.454 3.100 0.417 0.865 0.870 10.39
SESA3 0.60 20%6.73 89%11.27 0.211 --0.003 0.002 0.006 0.476 0.481 3.146 0.429 0.904 0.910 11.33
SESA4 0.60 20%6.62 87%11.27 0.210 --0.003 0.003 0.007 0.507 0.514 3.028 0.405 0.912 0.919 11.10
44
Table 3c. 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
45
Table 3d. 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
46
Table 3e. 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
47
Table 3f. 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
48
Figure 14. Comparison of nitrogen species (mg/L) in Nantucket Harbor in summers, 2010-2014 avg. (upper left, not including 2011); 2015
(upper right); 2016 (bottom) Total nitrogen is the sum of the inorganic and organic fractions (top line in each graph). All figures are to same
scale.
49
Figure 14 cont'd. Comparison of nitrogen species (mg/L) in Hummock Pond in summers, 2010-2014 avg. (upper left, not including 2011);
2015 (upper right); 2016 (bottom). Total nitrogen is the sum of the inorganic and organic fractions (top line in each graph). All figures are to
same scale.
50
Figure 14 cont'd. Comparison of nitrogen species (mg/L) in Sesachacha Pond in summers, 2010-2014 avg. (upper left, not including 2011);
2015 (upper right); 2016 (bottom). Total nitrogen is the sum of the inorganic and organic fractions (top line in each graph).
51
Figure 14 cont'd. Comparison of nitrogen species (mg/L) in Madaket Harbor in summers, 2010-2014 avg. (upper left, not including 2011);
2015 (upper right); 2016 (bottom). Total nitrogen is the sum of the inorganic and organic fractions (top line in each graph). All figures are to
same scale.
52
Figure 14 cont'd. Comparison of nitrogen species (mg/L) in Long Pond (Madaket Harbor System) in summers, 2010-2014 avg. (upper left,
not including 2011); 2015 (upper right); 2016 (bottom) Total nitrogen is the sum of the inorganic and organic fractions (top line in each graph).
All figures are to same scale.
53
Figure 14 cont'd. Comparison of nitrogen species (mg/L) in Miacomet in summers, 2010-2014 avg. (upper left, not including 2011); 2015
(upper right); 2016 (bottom). Total nitrogen is the sum of the inorganic and organic fractions (top line in each graph). All figures are to same
scale.
54
Figure 15. Summer 2016 TN concentrations compared to 2015 and average of 2010-2014 not including
2011.
Figure 15 cont'd. Summer 2016 TN concentrations compared to 2015 and average of 2010-2014 not
including 2011.
55
Figure 15 cont'd. Summer 2016 TN concentrations compared to 2015 and average of 2010-2014 not
including 2011.
Figure 15 cont'd. Summer 2016 TN concentrations in Madaket Harbor compared to 2015 and average
of 2010-2014 not including 2011.
56
Figure 15 cont'd. Summer 2016 TN concentrations compared to 2015 and average of 2010-2014 not
including 2011.
Figure 15 cont'd. Summer 2016 TN concentrations compared to 2015 and average of 2010-2014 not
including 2011.
57
Figure 16. Estuarine water quality monitoring station locations in the Nantucket Harbor
estuary system. Station labels correspond to those provided in Table 3 below. Red diamonds
indicate locations of MEP monitoring stations. Blue diamonds are locations of Town sampling.
Station 8 sampled in 2010, station 8N sampled in 2011, 2012, 2013, 2014, 2015, 2016.
58
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, 2014, 2015 and 2016.
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)
2016
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 0.355
Head of the Harbor -
Lower 2A 0.339 0.070
NA NS NS NS
NS NS NS
Pocomo Head 3 0.335 0.081 NA NS NS NS NS NS NS
Quaise Basin 3A+Town 2 0.336 0.112 2 0.297 0.364 0.345 0.314 0.374 0.314
East Polpis Harbor 4+Town 6 0.362 0.105 6 0.438 0.484 0.401 0.378 0.404 0.371
West Polpis Harbor 4A+Town 5 0.388 0.119 5 0.431 0.419 0.385 0.389 0.422 0.420
Abrams Point 5 0.335 0.060 NA NS NS NS NS NS NS
Monomoy 6 0.297 0.086 NA NS NS NS NS NS NS
Mooring Area
7+Town 1,
1A 0.326 0.106
1, 7 0.332, 0.377 0.335, 0.379 0.323, 0.323 0.294, 0.284 0.39, 0.33 0.304, 0.319
Nantucket Sound OS+Town 4 0.239 0.041 4 0.283 0.3442 0.3171 0.277 0.297 0.283
59
Figure 17. 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.
60
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)
2016
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) 1.01 (1.003)
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, 2014, 2015 and 2016 represent the
average at Station 1, with the average of stations 1-4 in ( ).
61
Figure 18. Estuarine water quality monitoring station locations in the Madaket Harbor and Long Pond Systems.
62
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, 2014, 2015 and 2016 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)
2016
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 0.219
Madaket Harbor MEP M2 0.395 0.083
Madaket Harbor Town 2 0.436 0.444 0.323 0.347 0.418 0.338
Madaket Harbor MEP M3 0.415 0.090
Madaket Harbor Town 3 0.324 .356 0.314 0.376 0.324 0.260
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 0.434
Long Pond MEP LOPO1 1.058 0.404
Long Pond
MEP
LOPO2+Town 5 0.971 0.369 1.385 1.013 0.709 1.481 0.697 0.649
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 0.629
North Head Long P. MEP LOPO5 0.954 0.271
63
Hummock Pond
and
Miacomet Pond
Station ID's
2016 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)
TN
(mg/L)
Mean Mean Mean Mean Mean Mean Mean S.D.
HUM1 0.594 0.539 0.651 0.769 0.666 0.616 0.751** 0.374
HUM3 0.654 0.622 0.643 0.827 0.863 0.589 0.630** 0.388
HUM5 0.868 0.558 0.653 0.881 0.871 0.766 ND ND
HUM7 0.673 0.621 0.873 1.170 1.301 1.786 1.283** 0.969
HUM8 1.194 0.576 0.755 1.064 0.944 0.983 ND ND
MP1 0.772 1.297 0.864 0.792 0.828 0.854 0.842* 0.191
MP2 0.669 1.318 0.784 1.036 0.880 0.811 0.855* 0.213
MP3 0.783 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, 2015 and 2016. All values are
mg/L.
64
Low 20%2016
Station Secchi Oxsat DIN TON T-Pig EUTRO Health Status
ID SCORE SCORE SCORE SCORE SCORE Index
HUM7 46.1 0.0 19.8 3.3 43.7 22.6 Poor
HUM8 0.0 24.2 47.3 0.0 0.0 14.3 Poor
HUM5 2.0 0.0 42.9 0.0 0.0 9.0 Poor
HUM3 23.1 90.3 100.0 0.0 52.1 53.1 Moderate
HUM1 26.6 76.8 100.0 3.5 60.8 53.5 Moderate
LONG6 7.8 40.7 71.2 0.0 43.8 32.7 Mod-Fair
LONG5 15.9 0.0 100.0 0.0 46.1 32.4 Mod-Fair
MH1C 66.5 54.4 70.4 48.5 83.1 64.6 High-Moderate
MH1 61.9 18.4 44.3 58.7 87.2 54.1 Moderate
MH2 60.9 66.7 83.2 83.6 100.0 78.9 High
MH3 79.0 71.8 100.0 100.0 100.0 90.2 High
MH4 100.0 86.2 100.0 100.0 100.0 97.2 High
MP3 26.9 47.8 89.0 0.0 0.0 32.8 Mod-Fair
MP1 35.5 47.0 100.0 0.0 0.0 36.5 Mod-Fair
MP2 49.2 42.7 91.9 0.0 0.0 36.8 Mod-Fair
NAN3 84.6 62.5 100.0 73.2 80.7 80.2 High
NAN6 74.2 66.6 100.0 56.3 64.2 72.3 High
NAN6C 79.3 70.6 100.0 47.7 62.9 72.1 High
NAN5 64.0 59.4 100.0 50.4 45.2 63.8 High-Moderate
NAN2 79.1 74.9 100.0 89.9 100.0 88.8 High
NAN2A 84.6 54.7 100.0 56.2 57.8 70.7 High
NAN2AC 83.5 50.9 100.0 45.9 52.8 66.6 High-Moderate
NAN7 72.0 73.4 100.0 93.5 81.8 84.1 High
NAN1 83.9 74.6 100.0 87.2 100.0 89.1 High
NAN8N 47.9 61.9 100.0 100.0 100.0 82.0 High
NAN4 87.1 81.2 100.0 100.0 100.0 93.7 High
STA4 0.0 35.6 83.3 0.0 100.0 43.8 Moderate
STA4A 0.0 0.0 75.4 0.0 89.4 33.0 Mod-Fair
STA6B 0.0 21.0 75.4 0.0 100.0 39.3 Mod-Fair
SESA3 100.0 75.4 3.7 0.0 36.3 43.1 Moderate
SESA2 100.0 73.5 2.4 0.0 33.0 41.8 Moderate
SESA4 100.0 76.7 5.7 0.0 39.9 44.5 Moderate
SESA1 17.1 69.5 11.6 0.0 31.4 25.9 Poor
SESA1C 13.9 100.0 100.0 0.0 0.0 42.8 Moderate
ORS2 54.8 63.5 100.0 79.2 100.0 79.5 High
ORS4 37.0 0.0 99.8 64.0 90.5 58.3 Moderate
ORS6 40.0 55.3 73.3 12.7 58.8 48.0 Moderate
Table 7a. 2016 Trophic Health Index Scores and status for water quality monitoring stations in
Nantucket estuaries based upon open water embayment (not salt marsh) habitat quality
scales. Index calculated with Dissolved Oxygen data (described in Howes et. al., 1999 at
www.savebuzzardsbay.org).
65
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 7b. 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).
66
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 7c. 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).
67
Table 7d. 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
68
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 7e. 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).
69
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 7f. 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).
70
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 8a. 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).
71
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 8b. 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).
72
Table 8c. 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
73
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 8d. 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).
74
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 8e. 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).
75
Figure 19. 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.
76
Figure 20. 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. Station Nan-2A MEP Sentinel Station.
77
Figure 21. 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.
78
Figure 22. 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.
79
Figure 23. 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.