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2016 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.