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2017 Final Island-Wide Water Quality Report 1 Technical Memorandum FINAL Water Quality Monitoring and Assessment of the Nantucket Island-Wide Estuaries and Salt Ponds Update 2017 To: Town of Nantucket Marine and Natural Resources Department 2 Bathing Beach Road Nantucket, MA 02554 From: Brian Howes Ph.D. and Roland Samimy Ph.D. Coastal Systems Program School of Marine Science and Technology (SMAST) University of Massachusetts-Dartmouth 706 South Rodney French Blvd. New Bedford, MA 02744 February 28, 2018 2 The Technical Memorandum on the 2017 Nantucket Water Quality Monitoring Program is organized consistent with previous SMAST water quality monitoring summaries (2010 and 2012 - 2016) to allow direct comparison to data from the previous years of monitoring. The report does include summary tables for each year of the program so that this report can be used as a both the 2017 review and a program summary. As was the case with the 2016 summary, the 2017 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 2017 summary is focused specifically on the following: 1. Results of Sampling: Summary of Water Quality Results Nantucket Harbor Madaket Harbor Long Pond Hummock Pond Miacomet Pond Sesachacha Pond Polpis Harbor Streams Oyster Aquaculture Potential Sites 2. Trophic State: Water Quality/Eutrophication Status 3. Recommendations for Future Monitoring As in previous years, the 2017 water quality monitoring of Nantucket's fresh and saltwater systems was focused on summer-time conditions, as the warmer months typically have the lowest water quality conditions, hence are critical period for resource management. As in previous years (2010, 2012-2016), the 2017 approach utilized for the collection and analysis of water samples from each of the estuaries of Nantucket remains the same. This consistency is intended to maximize the value of the results by making the data perfectly cross-comparable to water quality monitoring data collected across the Island of Nantucket from previous years and to previous Massachusetts Estuaries Project results for Nantucket estuaries as well as more broadly to estuaries throughout the region (Cape Cod, Martha's Vineyard). In this manner, inter-ecosystem comparisons can be made to better assess system health/impairment and function and to formulate appropriate nutrient management strategies. This allows individual towns such as Nantucket to directly benefit from lessons learned throughout the wider region. It should be noted that in 2017 (as was the case 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, data analysis and overall program coordination. The Nantucket Natural Resources Department staff 3 primarily focused on coordination of field efforts, field sampling and data collection on physical parameters and water quality improvement efforts. The goals of the monitoring program remain unchanged from previous years, primarily to: 1. determine the present (2017) 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 development of potential alternatives for nutrient and resource management and quantitative measures of success. This latter point (3) is critical for restoration planning should a system be found to be impaired or trending toward impairment, which requires targeted management actions for restoration. As was the case in 2010, 2012, 2013, 2014, 2015 and 2016 sampling efforts, the 2017 sampling program focused on the summer/early fall months (June - September). In addition to the standard estuarine sampling, in the 2016 sampling season 2 additional sampling events were completed in Sesachacha Pond to monitor the efficacy of the spring opening (breaching barrier beach) and in Hummock Pond an additional event was completed in April to represent pre-opening conditions and the regularly scheduled May sampling event was utilized to determine water quality in the pond after the pond closed. Monitoring of the openings of Sesachacha Pond and Hummock Pond were NOT continued in 2017. Water samples were collected from 6 estuarine systems (Figures 1, 2, 3, 4 and 5) on multiple dates (“events”) following the schedule presented in Table 1a (2017), Table 1b (2016), Table 1c (2015), Table 1d (2014), Table 1e (2013), Table 1f (2012) and Table 1g (2010). Samples collected in 2017 were obtained from the same sampling station locations and the same depths as in previous years to maximize cross comparability and to gauge temporal changes. It should be noted that the Town of Nantucket did undertake water quality monitoring in 2011, however, those samples were analyzed by a lab other than the Coastal Systems Analytical Facility at the UMASS School for Marine Science and Technology. The 2011 water quality data were presented in tabular form in Appendix A in Annual Technical Memoranda of 2012 and 2013 and are not being reproduced again herein. As in all previous years, the physical/environmental parameters measured in the estuaries during the 2017 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 4 water quality monitoring undertaken in 2016 and 2017 included an additional 3 stream locations. During the summer 2016 season, stream station STA-3 was dropped due to no flow and a station STA-4a was added to clarify water quality conditions in the stream outflow associated with cranberry bogs up-gradient of STA-4. In 2017 a fourth stream station was added (WPH outlet) to directly measure flow and nutrient load into Western basin of Polpis Harbor. In total, 2017 stream sampling took place at 4 stations: STA-4, STA-4A, STA-6 and WPH outlet. In 2017, 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. The Town of Nantucket has been working for decades to protect and more recently restore its estuaries and their aquatic resources. At present, activities to lower nitrogen enrichment and its negative impacts to water and habitat quality are ongoing in 4 estuarine systems: Nantucket Harbor (jetties and sewers), Madaket/Long Pond (landfill), Sesachacha Pond (openings), Hummock Pond (refined opening protocol). In addition, all of the Town’s estuaries should benefit from the recent fertilizer application by-law. As a result, it is anticipated that the efficacy of these management activities should be seen in the on-going monitoring results. As detailed below, summer 2017 appears to have sustained high water quality for the Nantucket Harbor system (2017 embayment wide TN average of 0.353 mg/L, 2016 = 0.35 mg/L, 2015 = 0.37 mg/L). In contrast, Hummock Pond water quality appears to have continued the decline started in 2016 which showed a decrease in overall water quality compared to 2015 (2017 and 2016 embayment wide average TN = 1.01 and 0.80 mg/L (respectively), 2015 = 0.58 mg/L), likely due to the poor opening success in spring 2017 (1.5 days) and higher precipitation, as the spring opening in 2016 compared well with the duration of the opening in 2015 (18 days and 15 days respectively). Long Pond TN concentrations have improved over historic levels although the reduction appears to be stabilizing. Miacomet Pond, which is now functionally a eutrophic freshwater pond, saw a slight improvement in 2017 as seen in lower TN concentrations and lower total pigments (CHLA + Pheophytin). Water Quality in Sesachacha Pond appears to be directly related to the efficacy of its seasonal openings. Water quality in 2010, 2012, 2013 (mean TN = 0.671 mg/L, Chla = 5.5 ug/L) was significantly improved over the levels observed previously in the MEP analysis. The lower TN levels in Sesachacha Pond (2010-2013) versus historic levels documented by the MEP indicated improvement of pond resources most likely due to modified breaching of the pond as recommended by the MEP analysis. Since there was no major shift in nitrogen loading within the Sesachacha Pond watershed during that period of improvement, it is almost certain that the amount of tidal flushing during a given artificial breaching is driving the variability in the observed summer TN level. The rise in TN observed during the 2014 sampling suggests that a poor inlet opening may have occurred in spring 2014, as it is unlikely a significant change in the watershed load occurred to drive the increase in TN from one summer to the next. Short openings in subsequent years (2015 {5 days}, 2016 {3 days}, 2017 {7 days}) suggests that inlet opening efficacy has a significant effect on pond water 5 quality as TN concentrations from 2014 to 2017 have steadily increased to nearly the same level as when the MEP analysis was completed. In recent years (2014-2017) water quality has declined (mean TN = 0.933 mg/L, Chla = 8.4 ug/L) and is again approaching MEP levels of enrichment. The amount of flushing with the openings is reflected in the significantly higher salinities in 2010-2013 versus 2014-2017, 17.9 PSU and 11.6 PSU, respectively. Higher salinities reflect more flushing which is correlated with lower TN and total chlorophyll a levels. The 2016 water quality analysis confirmed that the significant improvement in Sesachacha Pond seen previously had diminished and the Pond has declined in nitrogen related water quality over the past 4 years (2014- 2017) almost certainly due to the quality of the inlet openings. The important role of the pond openings is further supported by the fact that average TN concentration in Sesachacha Pond was higher (1.00 mg/L TN) in 2016 which received a 3 day opening compared to average TN concentrations observed in 2017 (0.88 mg/L TN) given a 7 day opening. These results indicate that the recent decline in water quality observed in Sesachacha Pond since 2014 should be readily reversible if sufficient flushing can be maintained. The effect of improved pond flushing is discussed in detail in the MEP Sesachacha Pond Nutrient Threshold Report submitted to the Town of Nantucket in 2006. Table 1a. Sampling Schedule for 2017 Nantucket Water Quality Monitoring Program Month Nantucket Harbor Madaket Harbor Long Pond Sesachacha Pond Miacomet Pond Hummock Pond Polpis Streams Oyster Sites Jan Feb February 8 Mar March 30 March 29 March 27 April April 27 May May 18 May 16 May 10 May 4 May 4 May 3 May 23 May 17 June June 14,29 June 27 June 13 June 22 June 19 June 12 June 14 July July 12,27 July 11 July 10 July 6,31 July 6 July 10 July 5 July 12 August August 10,24 August 9 August 7 August 3 August 7 August 15 August 10 September Sept. 25 Sept. 12 Sept. 27 Sept. 5 Sept. 5 Sept. 13 Sept. 11 Sept.25 October Oct. 24 November December Total Events 8 5 5 6 5 5 9 5 6 Table 1b. Sampling Schedule for 2016 Nantucket Water Quality Monitoring Program Table 1c. Sampling Schedule for 2015 Nantucket Water Quality Monitoring Program Month Nantucket Harbor Madaket Harbor Long Pond Sesachacha Pond Miacomet Pond Hummock Pond Polpis Streams Oyster Sites Jan Feb Mar 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 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 7 Table 1d. Sampling Schedule for 2014 Nantucket Water Quality Monitoring Program Note: * The September 15 sampling of Nantucket Harbor only involved one station (NAN-4). Table 1e. Sampling Schedule for 2013 Nantucket Water Quality Monitoring Program Month Nantucket Harbor Madaket Harbor Long Pond Sesachacha Pond Miacomet Pond Hummock Pond Jan Feb Mar April May May 6 May 14 May 20 May 14 May 7, 19 June June 4, 17 June 19 June 11 June 12 June11 June 10 July July 1, 17 July 2 July 23 July 30 July 30 July 23 August Aug 4, 14 Aug 18 Aug 21 Aug 19 Aug 19 Aug 21 September Sept 2, 15* Sept 15 Sept 4 Sept 4 Sept 18 Sept 18 October November December Total Events 8 4 5 5 5 6 Month Nantucket Harbor Madaket Harbor Long Pond Sesachacha Pond Miacomet Pond Hummock Pond Jan Feb Mar April May May 28 May 22 May 22 May 21 June June 13, 25 June 12 June 4,26 June 5 June 5 June 6 July July 17, 30 July 16 July 10 July 9 July 9 July 2 August Aug 13, 28 Aug 12 Aug 21 Aug 21 Aug 6 Aug 14 September Sept 9 Sept 10 Sept 24 Sept 19 Sept 24 Sept 18 October November December Total Events 7 5 5 5 5 5 8 Table 1f. Sampling Schedule for 2012 Nantucket Water Quality Monitoring Program Table 1g. Sampling Schedule for 2010 Nantucket Water Quality Monitoring Program Month Nantucket Harbor Madaket Harbor Long Pond Sesachacha Pond Miacomet Pond Hummock Pond Jan Feb Mar April May May 29 June June 7, 28 June 12 June 25 June 20 June 20 June 27 July July 9, 26 July 11 July 24 July 19 July 19 July 31 August Aug 7, 22 Aug 8 Aug 21 Aug 23 Aug 23 Aug 24 September Sept 6 Sept 7 Sept 25 Sept 25 Sept 27 Sept 26 October November December Total Events 8 4 4 4 4 4 Month Nantucket Harbor Madaket Harbor Long Pond Sesachacha Pond Miacomet Pond Hummock Pond Streams Jan Feb Mar April May May 18 May 20 May 19 May 26 May 26 May 25 June June 2, 17 June 3, 15 June 17 June 24 June 24 June 29 June 28 July July 1, 15, 30 July 16, 27 July 29 July 26 July 26 July 28 August Aug. 13 Aug. 12, 30 Aug. 11 Aug. 26 Aug. 26 Aug. 27 September Sept. 1, 14 Sept. 13 Sept. 15 Sept. 23 Sept. 23 Sept. 28 October Oct. 21 November December Totals 10 8 5 5 5 5 1 9 Figure 1. Madaket Harbor and Long Pond sampling stations 2010, 2012, 2013, 2014, 2015, 2016 and 2017. 10 Figure 2. Nantucket Harbor sampling stations 2017. Station NAN-8 (the cut) was only sampled in 2010 and location changed in 2011 - 2017. Nantucket Harbor and Polpis Harbor each have nitrogen thresholds in the MassDEP/USEPA TMDL for this system. 11 Figure 3. Sesachacha Pond sampling stations 2010, 2012, 2013, 2014, 2015, 2016 and 2017. This system has a nitrogen threshold set in its site-specific MassDEP/USEPA TMDL.. 12 Figure 4. Hummock Pond sampling stations 2010, 2012, 2013, 2014, 2015, 2016, 2017. 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. 13 Figure 5. Miacomet Pond sampling stations 2010, 2012, 2013, 2014, 2015, 2016, 2017. Miacomet Pond is currently functioning as a freshpond. Station 3 Station 1 Station 2 Station 3 Station 1 Station 2 14 Figure 6. Polpis Harbor Stream Sampling locations (ST-4, 4A, 6B and WPH-outlet). Stream sites sampled in 2016 and 2017 (shown as yellow pins). WPH-outlet sampled only in 2017. Water samples from mid depth in water exiting culverts. Figure 6a. Polpis Harbor Stream Sampling locations (ST-4, 4A, 6B and WPH-outlet) relative to estimated direction of flow as determined by the Town of Nantucket. 15 Figure 6b. Polpis Harbor Stream Sampling locations (ST-4, 4A, 6B) 2016 (shown as yellow pins). Water samples from mid depth in water exiting culverts. Figure 6c. Polpis Harbor Stream Sampling locations (ST-3,4,6B) 2015 (yellow pins). Water samples from mid depth in water exiting culverts. ST-3 was dropped in 2016 due to zero flow. 16 Figure 7a. Sampling locations associated with potential oyster aquaculture deployments in Nantucket Harbor (ORS-2,3,4,5,6) and Madaket Harbor (ORS-1) sampled in 2015. ORS-2,4,6 sampled in 2016 and 2017. Sites are associated with possible oyster aquaculture areas (yellow pins). ORS4 was the selected reef location and reef construction began in June 2017. Spat on shell was deployed in the Fall 2017. Figure 7b. Oyster Aquaculture Sampling location Madaket Harbor (ORS-1) 2015 (yellow pin). Site is associated with possible oyster aquaculture areas but was not sampled in 2016 or 2017. 17 Summary of 2017 Water Quality Results for Nantucket Sampling Estuarine Water Quality: While there were some localized areas supporting inter- annual variation in water quality (Hummock Pond {-}, Miacomet Pond {-}, Long Pond {-}1, see below), the overall trends in water quality observed in 2017 follow and expand the pattern observed in previous years. As in previous years, water samples collected from June through September in the estuarine systems indicate that organic nitrogen (dissolved + particulate) dominates the Total Nitrogen pool (86%-99% in 2017 depending on the estuary vs. 92-98% in 2016 and 96% in 2015 alone), while bio- available nutrients in the form of nitrite+nitrate (NOx) and ammonium (NH4) (combined DIN) account for 1% - 10% in 2017 compared to 2% - 10% of the TN pool in 2016 and 4% of Total Nitrogen pool in 2015 (Tables 3a,b,c,d,e, f, g and Figures 15,16). 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 2017 (Table 3a), as noted in prior years as well (Tables 3b,c,d,e,f,g). Consistent with the water clarity and TN levels, corresponding chlorophyll-a pigment concentrations are lowest (1-5 ug/L) at the outer stations of these well flushed systems (Table 3a,b,c,d,e,f,g Figure 8,9). The observed level of variation is common and underscores the need for long-term monitoring to detect water quality trends. Nantucket Harbor and Madaket Harbor are both well flushed basins but tended to have slightly higher phytoplankton biomass (chlorophyll-a) in 2017 compared to 2016 (all stations in Madaket Harbor and most stations in Nantucket Harbor). In Nantucket Harbor, station Nan-5 showed a lower level of total pigment in 2017 compared to 2016, however, the difference was slight and the levels in both years were relatively low (4.8 ug/L and 5.8 ug/L respectively). In Madaket Harbor the total pigment levels in 2017 were consistently higher compared to most other years except 2010 which showed higher chlorophyll levels than all years monitored to date. This is consistent with the water clarity observed in 2017 (Nantucket Harbor station 3 secchi depth 2015 = 1.45 m, 2016 = 2.34 m, 2017 = 2.30m, Madaket Harbor MH-2 secchi 2.2 meters in 2015, 1.7 meters in 2016, 1.68 meters in 2017) as turbidity is primarily the result of organic particulates, e.g. phytoplankton. The parallel measurements of total nitrogen (TN) are generally consistent with the chlorophyll-a results, showing a positive relationship between changes in TN levels with changes in chlorophyll-a levels (see below). This is particularly apparent in Nantucket Harbor (station 5 and 6, Polpis as well as station 2 mid harbor and station 2A sentinel station) and provides additional evidence that nitrogen is controlling the level of eutrophication in these systems. 1 {+} indicates improved conditions in 2017; {-} indicates declining conditions in 2017. 18 Figure 8. Average Chlorophyll-a (CHLA) concentrations by station in the well flushed Nantucket Harbor system during the summer 2017 sampling season. Stations Nan-5 and 6 are in Polpis Harbor the rest relate to the main basin. Note that 2017 levels were about average within the upper basins (Nan-5 slightly lower in 2017 compared to 2016, Nan-6 slightly higher in 2017 compared to 2016) 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 2017 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 had not been as prevalent in follow-on years however in 2017 total pigment levels were notably higher at stations MH-1 and MH-2 compared to 2016. 19 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. Average chlorophyll-a concentrations in the poorly flushed basins of Long, Hummock, Miacomet and Sesachacha Ponds in 2017 were were 16.5 ug/L (max. 23.5 ug/L), 22.5 ug/L (max. 33.3 ug/L), 9.7 ug/L (max. 11.3 ug/L) and 9.0 ug/L (max. 11.3 ug/L), respectively. By comparison, 2016 chl-a levels 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 Long, Hummock, Miacomet and Sesachacha Ponds monitoring results for 2015 (5.4 ug/L, 4.5 ug/L, 41.3 ug/L and 6.8 ug/L) with highest chlorophyll levels generally being observed in the freshwater Miacomet Pond basin, though Hummock Pond and Sesachacha Pond can show even higher levels during periods when they freshen due to poor openings. In Hummock Pond chlorophyll-a levels were noticeably higher in 2017 compared to slightly in 2016 vs. 2015, likely due to a less effective opening in 2017 (a persistent bloom of Dolichospermum was also observed for a significant portion of the 2017 sampling period). The low flushing of Hummock Pond in 2017 can be seen in the low salinity (3.5 PSU) compared to 2016 and 2015 (6.5 and 5.8 PSU, respectively) with resultant half of the summer chlorophyll levels. The multi-year results clearly show that 2010 was the poorest water quality year, 2010-2017, in each of Nantucket’s estuaries. Over the past 4 years, chlorophyll-a levels in Long Pond, Hummock Pond, Miacomet Pond and Sesachacha Pond have declined compared to historic levels (MEP) and 2010 but do show interannual variation (e.g. all ponds higher in 2017 compared to 2016) due to differences in opening duration, rainfall, temperature, etc. 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 historic chlorophyll-a levels were generally >20 ug/L, frequently >60 ug/L, with 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 with successful openings, but has showed recent decline, 2014-2017. However, conditions remain improved over historic levels. The 2012- 2013 conditions approached the TMDL target TN levels to restore nitrogen impaired habitats, with the recent trend (2014-2017) showing continuing decline with TN levels in 2017 higher than the previous year, 2016 with an associated increase in total pigment levels (potentially related to a less effective opening in 2017 {7 day spring opening} compared to 2016 {3 day spring opening} compared to 2015 {5 day spring opening}). Given that opening duration may not accurately reflect flushing success in all cases, salinity was analyzed as the response to tidal flushing. In this case it appears that the low nitrogen/chlorophyll years (2012 & 2013) also had the highest salinities on record (24.7 and 17.0 PSU), whereas the recent water quality decline is under salinity conditions of 11.3-11.6 PSU. Note that the MEP indicates that a salinity of 22 PSU should be associated with high water quality in Sesachacha Pond, consistent with the monitoring program results. It is important to note that creating sustained openings in Sesachacha Pond is difficult due to the dynamic coastal processes which move to refill and close the tidal channel. However, when openings have been successful there was a dramatic improvement in pond water quality. It appears from all of the accumulated information that it is unlikely that the Town will be able to 20 reproducibly have good openings despite planning openings based on weather and tides, therefore a combination of openings and nitrogen management will likely be needed. As previously noted in past summary reports, the temporal data indicate that both Sesachacha Pond and Hummock Pond can be significantly restored by effective pond openings and that salinity is a good metric from which to gauge opening “success” (higher resultant salinity = lower TN). As more data is available, it will be possible to derive predictions of the water quality response from opening metrics which can then be used by the Town in refining what is a difficult process of pond openings. In the case of Sesachacha Pond, where openings are through a barrier beach subject to very active coastal processes, if openings cannot be made more effective, it may be necessary to consider nutrient load reducing strategies in the watershed or in situ processes to improving water quality, such as use of oysters to lower TN levels. This in situ approach of using the filtering capacity of oysters to improve water quality is being considered by a number of towns on Cape Cod (Falmouth, Orleans, Mashpee) as well as across Buzzards Bay (Westport). After the high chlorophyll-a levels in 2010, 2012, Long Pond has maintained its phytoplankton levels at a moderate to high level. However, in 2017 the chlorophyll increased noticeably while 2016 remains as the lowest levels of record, a pattern mirrored in the TN results. The initial decline (post-2012) was noted in the previous 3 monitoring years and is possibly a result of activities at the landfill leading to declining nitrogen inputs to pond waters. Interestingly in 2017, while station LONG 5 showed a dramatic increase, station LONG 6 closest to the outflow point from Long Pond to Madaket Ditch,(while higher than most previous years) still showed similar chlorophyll levels as in past years, consistent with the observed algae bloom (Diatoms) in the lower portion of Long Pond furthest away from the outflow that was captured during the June and July sampling dates (personal communication, Kaitlyn Shaw). As previously recommended in 2016 and 2015, a detailed assessment of the current landfill effect on groundwater quality flowing to Long Pond would be critical to linking activities at the landfill with improvements observed in Long Pond and for making predictions as to the likely extent of improvement possible. It should be noted, however, that a benthic infaunal survey was undertaken in November 2017 by scientists from the Coastal Systems Program, UMD-SMAST, at the request of the Town of Nantucket. Sediment samples were collected using the same protocols as employed by the Massachusetts Estuaries Project thereby allowing direct cross comparison of 2017 and 2003 results when infauna was last surveyed by the MEP as part of the Long Pond habitat assessment. The 2017 infaunal survey results were not available at the time of this writing, however, the comparison of the 2017 and 2003 survey results will be available through the Town of Nantucket in early 2018. Additionally, nutrient testing of landfill effluent was initiated in 2017 by the Public Works department and CDM-Smith who already monitor the wells. These efforts will be used to update the nutrient load values to Long Pond based on new nitrogen concentrations and groundwater information and should be integrated into the detailed assessment of the effect of the landfill activities on Long Pond water quality. Presently, Long Pond is generally showing signs of improving. It does, however, continue 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, remains very fresh (avg. salinity 0.1-0.2 PSU), continues to show high chlorophyll-a levels (7.3 - 11.3 ug/L seasonal average), although 2017 and 2016 levels were generally lower than 2013 and 2015). Miacomet Pond is still clearly supporting poor water quality conditions with high TN, high PO4 and TP levels (station MP-3 {head} 21 0.050 mg/L and 0.100 mg/L respectively in 2017) and high chlorophyll-a levels, poor water clarity and moderate oxygen depletion, all indicators of a nutrient impaired basin. Additionally, given how fresh Miacomet Pond has become, phosphorous as a driver of nutrient impairment must be considered. The upper portion (Hum-8 and Hum-5) of Hummock Pond showed overall total pigment and chlorophyll-a levels in summer 2017 higher than 2016 and most other years in general. This is a significant shift as 2016 levels were lower than 2010, 2012, 2013 and showed moderate levels in the mid reaches but with stations in the lower portion (Hum-1 and Hum-3) closer to the barrier beach having slightly lower total pigment levels compared to most years. In 2017, the lower stations (Hum-1 and 3) were noticeably higher than 2010 levels which were previously considered the highest of all years monitored by the island-wide water quality monitoring program. The 2014 results remain the lowest levels measured over the 2010-2017 monitoring period and while 2016 was slightly higher than 2015 in the upper reaches of the system, chlorophyll levels in 2016 were still moderate-high as a metric of eutrophication. In 2017, chlorophyll levels at stations Hum-1,3,5 were all approaching 30 ug/L, 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 that may have been compromised in 2017. 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 in past years was the cause of the relatively low total pigment and TN conditions in the lower half of Hummock Pond in 2016. By comparison, in 2017 a spring opening was initially achieved but it lasted less than 1 day and was followed by another opening which only lasted 1.5 days in duration. The lack of an effective spring opening of Hummock Pond is likely the main contributor to the decreased nutrient related water quality observed in 2017, consistent with the lower overall pond (Stations 1-7) salinity (2017= 3.5 PSU; 2016=6.5 PSU indicative of less flushing in 2017. As flushing in the uppermost portions of Hummock Pond tend to be limited, total pigment and chlorophyll-a showed to be significantly higher at Hum-8 compared to 2016 but lower than the 2016 levels at Hum-7 as an observed algae bloom was unable to penetrate into the Head of Hummock Pond. This further supports the conclusion that the Head of Hummock is not tidally well connected to Hummock Pond through its narrow shallow channel. Total pigment and chlorophyll-a generally remains the lowest at each monitoring station in 2014 with 2015 and 2016 being the next lowest when compared to prior years. In April 2016 and 2015, Hummock Pond was opened and water levels and water quality were monitored before and after the opening. Both the April 2016 and 2015 openings appeared to be more effective than the fall 2014 opening as seen in the enhanced water quality during the 2016 and 2015 summers. Not surprisingly, in 2016 at station Hum-8 which showed elevated total pigment levels compared to 2015, average TN levels in the summer of 2016 were also higher than in summer 2015 (1.19 mg/L and 0.576 mg/L respectively) and in 2017 which showed the highest total pigment levels 22 (44.9 ug/L), associated TN levels where 1.20 mg/L. It appears that the lack of a significant spring opening allowed phytoplankton to build to bloom levels in 2017 compared to recent years. Additionally, in 2016 at station Hum-7 which showed similar total pigment levels compared to 2015, average TN levels in the summer of 2016 were nearly the same as in summer 2015 (0.674 mg/L and 0.621 mg/L respectively). In 2017, total pigment levels at Hum-7 were noticeably higher (13.9 ug/L) than in 2016 and 2015 (5.9 and 7.1 ug/L respectively) and associated with higher TN levels in 2017 was 0.789 mg/L. In general, it appears that the water quality in Hummock Pond does respond well to longer inlet openings as achieved in the spring of 2016 (18 days) and spring of 2015 (15 days). However as indicated by the elevated 2017 nutrient and total pigment results, the pond is very sensitive to the duration of openings. Further improvements are anticipated if openings can be made longer than 18 days or loads to Hummock Pond reduced. It should be noted that each consecutive year of good tidal exchanges lowers the overall TN level the following year until a new equilibrium is reached (likely 3-5 years). This has been observed in periodically opened ponds on Martha’s Vineyard (e.g. Edgartown Great Pond) and it stems from the fact that lowering TN levels requires time to build back up from watershed inputs and sediment recycling than if the TN levels remain high year around. Table A - 2017 Minimum, Maximum and Average CHLA and Total Pigment values for the closed ponds of Nantucket. 2017 min max avg min max avg System CHLA CHLA CHLA Total Pig Total Pig Total Pig (ug/L)(ug/L)(ug/L)(ug/L)(ug/L)(ug/L) Miacomet Pond 2.46 33.87 8.29 4.82 44.30 12.65 Sesachacha Pond 4.92 23.68 8.92 5.23 23.99 10.48 Long Pond 0.57 31.04 11.51 5.24 36.70 14.19 Hummock Pond 2.89 65.26 19.93 2.91 88.96 24.72 Table B - 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 23 Table C - 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 2017 sampling season compared to 2010, 2012, 2013, 2014, 2015 and 2016. 24 Figure 11. Average Total Pigment (Chlorophyll-a +Pheophytin) concentrations by station in the seasonally opened Hummock Pond system, during the summer 2017 sampling season compared to 2010, 2012, 2013, 2014, 2015 and 2016. Figure 12. Average Total Pigment (Chlorophyll-a +Pheophytin) concentrations by station in the Miacomet Pond system during the summer 2017 sampling season compared to 2010, 2012, 2013, 2014, 2015 and 2016. Miacomet Pond is not opened to the Atlantic Ocean and now contains freshwater (<0.2 PSU). 25 Figure 13. Average Total Pigment (Chlorophyll-a +Pheophytin) concentrations by station in the seasonally opened Sesachacha Pond system during the summer 2017 sampling season compared to 2010, 2012, 2013, 2014, 2015 and 2016. Average Total Nitrogen values for all of Hummock Pond (MEP TN threshold = 0.50 mg/L, HUM-3) were higher in 2017 with a commensurate increase in total phytoplankton pigment throughout the pond. By comparison, in 2016 total pigment appeared slightly lower in the bottom half of the pond and slightly higher in the upper half compared to 2015. Total nitrogen averaged 1.01 mg/L in 2017 whereas in prior years [2016, 2015, 2014, 2013, 2012, 2010] average TN values were [0.797, 0.583, 0.715, 0.900, 0.923, 0.944 mg/L] respectively. However, the pattern for the whole of Hummock Pond is somewhat deceptive given the strong TN gradient from the upper stations (Hum 7 & 8) and the lower stations (Hum 1 & 3). The lower stations, most influenced by the breaches, showed the largest improvement 2014-2016, with 2016 showing the lowest TN levels to date approaching the TMDL threshold level. The gradient was also seen in 2017 (lower stations better than upper stations), however, given the short breach, TN levels remained significantly higher than in 2016 with the associated effect of high total pigment and chlorophyll levels. This inter-annual variation follows the pattern of improved flushing observed in fall 2014, 2015 and 2016 under effective openings, and decreased water quality under the poor flushings from spring 2014 and spring 2017. Relative to the 2012-2017 and 2010 data sets, results indicate that within Hummock Pond, less so Long Pond and Miacomet Pond, there is a general gradient of nutrient (N and inorganic P) and chlorophyll concentrations from high levels in the upper, more enclosed and poorly flushed reaches of the estuaries to lower concentrations closer to the outlets where flushing is more effective (Figure 15,16). The gradient appears to be a bit flatter in 2016 for both Long Pond and Miacomet Pond but more pronounced in 2017. Based on average TN values in Hummock Pond, water quality in 2017 appears lower compared to 2016 and well above the nitrogen threshold needed for restoration. 26 In contrast, Miacomet Pond (No MEP threshold set) which has had no restoration activities or openings in recent decades showed only slightly lower TN levels in 2017 (0.711 mg/L) compared to 2016 (0.742 mg/L) and significantly lower TN levels than in 2015 (1.203 mg/L) and the previous 4 years of monitoring [1.202, 0.982, 0.962, 0.919, 0.886 mg/L]. Not surprisingly, average total pigment values in 2017 and 2016 were similar (14.11 and 14.10 ug/L respectively). It is not clear what has caused the recent reductions (2017 and 2016), but as a freshwater pond, Miacomet is highly influenced by freshwater inflows and may be responding to lower freshwater inflows associated with the drought in 2016, but this is purely speculative and would need site-specific confirmation. It should be noted that although Miacomet Pond’s TN levels were observed to be lower in both 2017 and 2016 compared to previous years, the levels are still quite elevated and the pond is clearly impaired by excess nutrients (N & P). The high levels of TN in these poorly flushed estuaries clearly contrast with the levels of TN and pigment in Nantucket’s well flushed estuaries (Nantucket and Madaket Harbors). The effect of reduced flushing is to increase the sensitivity of an estuary to nutrient inputs as water exchange rates are diminished. In addition to TN, the measured TP levels in Miacomet Pond in 2015 and 2016 were also quite high (MP-1: 45-85 ug/L; MP-2 68-80 ug/L; MP-3: 65-136 ug/L; Tables 3a & 3c). If Miacomet Pond is to be managed as a freshwater pond then phosphorus needs to be considered (with nitrogen) as a concern. Since no fresh pond or lake nutrient TMDLs have been developed on Cape Cod or Nantucket, SMAST’s 2001 survey of 190 lakes and ponds on Cape Cod was used by the Cape Cod Commission to develop potential region-specific nutrient thresholds.2 This review used an EPA method that relies on a statistical review of the available data within an eco-region to develop the thresholds.3 This review suggested a target TP concentration range for Cape Cod ponds between 7.5 and 10 µg/L to sustain high quality pond habitats. Potential target threshold ranges were also developed for total nitrogen (0.16 to 0.31 mg/L), and chlorophyll-a (1.0 to 1.7 µg/L). These concentrations closely approximated the EPA eco-region reference criteria available at the time for the region.4 These Cape Cod- specific thresholds can be used as guidance targets for Miacomet Pond, they have not been formally adopted as regulatory standards by MassDEP. However, it is clear even from the limited TP data available that phosphorus levels within Miacomet Pond are consistent with an impaired freshwater pond, which is supported by the high TN and chlorophyll-a levels. 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 significantly declined in 2016 and 2017 (0.742 mg/L and 0.711 mg/L). Chlorophyll-a levels were also significantly lower in 2017 and 2016 compared to 2015 and 2015 still remains the highest level observed. However, in its present freshwater condition it is not clear what is the primary nutrient for management (N, P, or N+P). Miacomet Pond in 2017 as in 2016-2014 likely 2 Eichner, E.M., T.C. Cambareri, G. Belfit, D. McCaffery, S. Michaud, and B. Smith. 2003. Cape Cod Pond and Lake Atlas. Cape Cod Commission. Barnstable, MA. 3 U.S. Environmental Protection Agency. 2000. Nutrient Criteria Technical Guidance Manual: Lakes and Reservoirs. First Edition. EPA-822- B00-001. US Environmental Protection Agency, Office of Water, Office of Science and Technology. Washington, DC. 4 U.S. Environmental Protection Agency. 2001. Ambient Water Quality Criteria Recommendations. Information Supporting the Development of State and Tribal Nutrient Criteria for Lakes and Reservoirs in Nutrient Ecoregion XIV. EPA 822-B-01-011. US Environmental Protection Agency, Office of Water, Office of Science and Technology, Health and Ecological Criteria Division. Washington, DC. 27 had phytoplankton production (e.g. chlorophyll-a) stimulated by both N and P inputs as pond salinities declined to present levels. As TP and PO4 samples were collected in parallel with the nitrogen fractions in the 2017-2014 surveys of Miacomet Pond, it was possible to assess eutrophication from N and P. N/P ratios can be compared to the idealized Redfield Ratios (C:N:P, 106:16:1) to get a first approximation of the degree to which N or P maybe structuring the pond. Interestingly, particulate C/N ratios remain relative consistent from the head to the lowest basin of the pond closest to the ocean (MP3 - MP1 - MP2, C/N ratio in 2017 of 7.5, 7.7, 8.4, in 2016 of 7.3, 6.9, 8.6 and in 2015 6.5, 6.8, 6.5 respectively, Redfield C/N ratio is 6.62). This supports the contention that phytoplankton comprise almost all of the particulate matter in the pond. The nutrient data showed significant variation between the pond basins, with total N/P ratios lower at the head and increasing to the middle and lower portions (MP3 - MP1 - MP2, for a total N/P ratio in 2017 of 20.1, 35.4, 40.9, in 2016 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 2017 and 2016, although only for the middle and lower pond in 2015. It is also important to note that orthophosphate concentration are quite low in the main basin (MP- 1, MP-2) generally <0.2 uM, such that adding phosphorus to this basin in mid summer would likely stimulate phytoplankton growth. In contrast, the upper station (MP-3 generally supports 2x-3x higher phosphate levels. It is likely that regions of the pond may be sensitive to both nitrogen and phosphorus, such that overall both nutrients need to be monitored and considered for management of Miacomet Pond, although phosphorus management is clearly needed at this time. As previously recommended, to refine this approximation of the limiting nutrient for Miacomet Pond, nutrient ratios from the monitoring effort should be coupled to controlled biotests (bottle tests, mesocosms) with different levels of P and N amendments to the natural phytoplankton community. These types of biotests were employed by the Coastal Systems Program for an assessment of other low salinity ponds, Oyster Pond in Falmouth and Cockeast Pond in Westport, specifically to better determine the degree of N or P limitation for nutrient management purposes. Comparison of algal biotest results and chemical nutrient concentrations in lakes has suggested that a mass N:P ratio above 20 indicates P limitation, a ratio below 10 indicates N limitation and values between 10 and 20 indicate that either of the nutrients may be limiting." (Petri Ekholm, Finnish Environment Institute, 2008). That there is variation in N/P ratios in the different basins of the pond suggests that some regions could be either N limited or P limited (or both). A more detailed examination of N and P cycling is warranted to ascertain which is playing a bigger role in the nutrient cycling of the pond system as a whole. At present, this pond continues to appear to have shifted from a eutrophic brackish water system to a eutrophic freshwater ecosystem and should potentially be managed as such, taking into consideration which nutrient is dominant (N vs. P). However, management must include that periodic overwash from storms could upset the ecological balance of this system if it were managed purely as a freshwater system. All of the estuarine stations in Nantucket’s estuaries are clearly nitrogen limited, based upon various assessments including the MEP. 28 Table D - below shows various nitrogen to phosphorous ratios from Miacomet Pond during the summer 2017 sampling season. Station Id.N/P PC/PN DIN/DIP TN/TP (2016)organic particulate inorganic total MP-3 34.7 7.5 3.4 20.1 MP-1 39.6 7.7 7.0 35.4 MP-2 43.9 8.4 12.4 40.9 Table E - below shows various nitrogen to phosphorous ratios from Miacomet Pond during the summer 2016 sampling season. Table F - 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 also show inter-annual variations in both Long Pond (MEP secondary threshold, Long Pond basin average 0.80 mg/L) in 2017 (0.787 mg/L) versus 2016-2012 and 2010 of 0.640, 0.677, 1.14, 0.795, 0.94,1.75 mg/L and in Sesachacha Pond (MEP threshold < 0.60 mg/L, SES-1) 0.960 versus 1.000, 0.904, 0.922, 0.669, 0.704, 0.639 mg/L. Like Hummock and Miacomet Ponds, Long Pond and Sesachacha Ponds are poorly flushed with Miacomet Pond not having been opened in over a decade and Long Pond having a poor hydraulic connection to Hither Creek / Madaket Harbor via Madaket Ditch. In the case of Sesachacha Pond, the TN levels also appear to be related to the success of the periodic 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 29 openings. The similar TN levels in 2017, 2016 and 2015 (0.960, 1.00 mg/L and 0.904 mg/L respectively) are predicted from the similar Spring opening durations (5 days Spring 2015, 3 days Spring 2016, 7 days Spring 2017) and are higher than the previous years which had better openings and associated lower subsequent TN levels (<0.704 mg/L). It is worth noting that the very high historic levels (1.20 mg/L) and 2010 levels were under less robust opening conditions, prior to the Town’s new awareness of the importance of openings as a pond management tool. It should be noted that Sesachacha Pond TN levels in 2017 and 2016 (and 2015) are still lower than during the MEP assessment and suggest that achieving the TMDL may be possible by refined openings, saving infrastructure costs. Additionally, it appears nutrient related water quality is worsening as a function 2014-2017 poor openings. As previously mentioned above, in the case of Sesachacha Pond, where openings are through a barrier beach subject to very active coastal processes, if openings cannot be made more effective (e.g. like 2010, 2012, 2013), it may be necessary to consider nutrient load reducing strategies in the watershed or in situ processes to improving water quality, such as use of oysters to lower TN levels, as is being considered by a number of towns on Cape Cod (Falmouth, Orleans, Mashpee) as well as across Buzzards Bay (Westport). Average TN levels in all 4 ponds are significantly higher than average values in the “offshore” stations NAN 4 and MH4 which average 0.288 [0.283, 0.297, 0.277, 0.317, 0.344, 0.302] and 0.306 [0.219, 0.328, 0.254, 0.278, 0.297, 0.285] mg/L, respectively (Tables 3a, 3b, 3c, 3d, 3e,3f, 3g, Figures 1, 2). It should be noted that the average offshore TN concentration for station MH4 is 0.295 mg/L if the 8/5/2015 sampling date (TN concentration = 0.427 mg/L) is not included in the calculation. It appears that sample data for that one sampling date is aberrant, which is supported by statistical analysis of the complete data set (2010-2017). Long Pond (MEP secondary threshold = 0.80 mg/L) 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. In 2017, data indicate that TN levels increased to 0.867 mg/L, however, the duration of this shift to higher TN levels is unknown at present and is likely related to the unusually large plankton bloom in 2017 in lower Long Pond. The general decline from historic levels, 2010 to 2016 in TN levels at station 5 needs to be tracked closely by the monitoring program, as MEP modeling suggests that conditions will improve significantly in Long Pond as the landfill TN load diminishes. Similarly, Station 6 also shows declining TN levels from historic to 2010 to 2016 samplings. Station 6 TN concentrations in 2016 declined to the lowest on record, 0.629 mg/L even lower than 2015, 0.656 mg/L, with 2014 being 0.788 mg/L and historic levels being 0.84 mg/L. In 2017, TN levels at station LONG6 increased to 0.712 mg/L, consistent with the observed increase at station LONG5. Based on the previous declines in TN concentrations observed in 2016 and 2015 and the increase at both stations in 2017, it appears that there is inter-annual variation that must be accounted for in Long Pond. Continued monitoring of stations 5 and 6 is warranted to confirm the downward trend in TN concentrations observed in past years. Overall, the monitoring results, both long term and over recent years, show a clear decline in TN from historic to 2016 levels, with TN levels at both stations in both 2015 and 2016 being less than half of previous observations. However, the slight increase measured in 2017 should be tracked and 30 more specific investigation into the nutrient load reductions related to work at the landfill should be undertaken, perhaps through use of the MEP modeling tool, to determine if the general downward trend is landfill related. The long-term lowering of the TN levels, particularly at station 6, is consistent with on- going Town activities at the landfill (mining and capping), as 2016, 2015, 2014 and 2013 TN levels follow a downward trend and chlorophyll-a levels in Long Pond are significantly lower than in 2010 and 2012 and generally similar to what was measured in 2013, 2014 and 2015 but with 2016 levels being the lowest on record. While TN levels measured in 2017 do appear higher and at odds with the decreases measured over the past few years, they cannot be considered erroneous as the observed increase in TN concentrations is matched by observed increases in chlorophyll and total pigment. Therefore, the monitoring program should continue to track the improvements in water quality at station 5 and 6 and the Town may want to continue to measure nutrient water quality in the wells down gradient of the land fill (as initiated by the Town DPW assisted by CDM-Smith) to 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. Additionally, it may be warranted to re-run the MEP water quality model with the new landfill loads based on all the upgrades completed to date to see how the modeling results match the water quality observations from the past few years. Results of updated scenario runs using the MEP developed modeling tool and new loads will support adaptive management approaches ultimately steering decision makers to the most cost effective solutions for restoration. As in all previous years, in Sesachacha Pond (MEP threshold <0.60 mg/L, SES-1), there is no noticeable nutrient or chlorophyll gradient among any of the 4 Stations (Figure 13 and 15, Tables 3a,b,c,d,e,f,g). The well horizontally mixed nature of this salt pond results from it only having periodic tidal exchange such that it operates more like a kettle pond than a tidal estuary. However, it should be noted that while TN and chlorophyll-a concentrations in Sesachacha Pond where generally higher in 2014 compared to 2013, TN levels in 2015 remained high (0.904 mg/L and 0.922 mg/L respectively), which continued through the 2016 field season. The slight rise in TN in 2016 (1.00 mg/L) is consistent with its limited opening. TN levels in 2017 appeared to drop from 2016 levels (0.884 mg/L vs. 1.00 mg/L). This does not seem unusual considering the duration of the spring 2017 opening compared to the spring 2016 opening. The spring 2017 opening lasted 7 days whereas the spring 2016 opening was only 3 days in duration. 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). On the contrary, while TN levels were lower in 2017 compared to 2015 and 2016, average total pigment levels were elevated in 2017 (10.6 ug/L) compared to 2016 but similar to what was observed in 2015 (11.07 ug/L). Given the diverse factors which can alter pigment levels (wind, light, temperature, nutrients, water clarity) the difference is similar to that seen in other systems throughout the region. That there was a noticeable increase from 2013 to 2014 and consistency between 2014, 2015, 2016 with an increase in 2017 is good reason to continue regular monitoring of the system, particularly to determine changes in the effectiveness of annual pond openings that are the likely driver for increased or decreased water quality in a given year. However, TN levels remain well above the nitrogen threshold in the TMDL, and the 2014, 2015 and 2016 TN increase is a cause for concern, particularly 31 after the few prior years of much lower TN levels (~0.6 mg/L). It appears the short duration spring openings in 2015 and 2016 are having a negative effect on pond water quality, however the longer (7-day) opening and the associated reduction in TN concentrations is a clear sign that longer openings achievable under the right conditions (wind direction, wind speed, wave state, lunar phase, pond stage) are effective for reducing nutrient levels in the pond. Consistent with previous years monitoring results, in 2017 Madaket Harbor (MEP threshold 0.45 mg/L, MH-1) showed a clear nitrogen gradient (and associated metrics) from Station 1 (0.57 mg/L) in Hither Creek (which receives discharge from Long Pond via Madaket Ditch), and is relatively poorly flushed, out to Station 2 (0.39 mg/L) in the Harbor, with further decreases out to the off-shore Station 4 (0.31 mg/L, Figure 9 and 15, Table 3a). Similarly, in Nantucket Harbor, there is a very small nutrient gradient from Wauwinet at the Head of the Harbor (Nan-3, 0.37 mg/L) and the more enclosed Polpis stations out to the entrance at Stations 8 (0.29 mg/L) and 4 (0.29 mg/L). There is also a chlorophyll gradient with the highest concentrations at the 2 Polpis Stations (5 and 6, 3.8 and 5.4 ug/L respectively) and Wauwinet basin, decreasing in the main Harbor and out to the off-shore Station 4 (3.8 ug/L). These levels within the main open basins are indicative of high quality habitat and nutrient related water quality. Average 2017 [2016, 2015, 2014, 2013, 2012, 2010] TN level in Madaket Harbor (Stations 1-3, not including Station 4, offshore) was 0.433 [0.343, 0.422, 0.390, 0.404, 0.485, 0.462] mg/L, compared to the off-shore Station 4, 0.306 [0.219, 0.328, 0.254, 0.278, 0.297, 0.285] mg/L. As mentioned above, due to the lack of a significant temporal trend, the best estimate of the offshore TN concentration for station MH4 is the average of all years (2010 to 2017, 0.281 mg/L). Average 2017 TN in Nantucket Harbor {MEP threshold = 0.35 mg/L at NAN-2A and 0.355 at NAN-6} (all stations except Station 4, offshore) remain quite low averaging 0.353 mg/L compared to 2010, 2012, 2013, 2014, 2015, 2016, with the offshore boundary station 4 averaging only 0.288 mg/L in 2017, slightly lower compared to offshore Madaket Harbor station MH-4 at 0.306 mg/L (Tables 3a, 3b). It should be noted that the 2010 value includes station NAN-8 (the cut) whereas the 2017, 2016, 2015, 2014, 2013 and 2012 value includes station NAN-8N which was relocated into the Town Basin within the Harbor (refer to Figure 2 for station location). Additionally, as specified in the nutrient TMDL developed by the MassDEP based on the MEP nutrient threshold analysis, an additional monitoring station was added in head of Nantucket Harbor (NAN-2A) to represent the water quality at the MEP sentinel station. In 2017, the TN concentration at station NAN-2A was 0.377. 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 0.377 mg/L, and for the sentinel station in Polpis Harbor (NAN-6) 0.355 mg/L versus 2017 TN level = 0.405 mg/L. Generally, conditions in Nantucket Harbor were not significantly different in 2017 compared to 2016. Estuarine Temporal Analysis: As the Nantucket Water Quality Program has collected 7 years of field data, it is possible to begin assessing long term trends. While this usually requires a decade of monitoring, we can conduct an initial analysis on “whole estuary results”. In this analysis all of the stations and events are averaged to yield an overall TN or total chlorophyll a value for an estuary for each year so that the complete time series can be evaluated. This approach can yield new information when examining 32 factors that affect entire estuaries, like increases or decreases in nitrogen loading or changes in tidal flushing. Smaller single year events, e.g. rainfall, show up as variability, as they are not long-term trends. Temporal analysis of Hummock Pond underscores the inter-annual variability within its main basin for key water quality indicators, TN and total chlorophyll-a, due primarily to the amount of flushing achieved through its spring opening (Figure 14a). While the openings in 2014-2016 brought the overall TN levels significantly down from prior years, the spring 2017 opening was insufficient to maintain these lower levels and TN level rose to the prior highs of 2014-2016. As such there is no consistent trend, but the results clearly indicate that TN levels can be lowered significantly in this basin through pond openings (down-up-down) almost to levels restorative of currently impaired habitats. However, given the variability in openings the Town may consider a hybrid approach of openings plus either in pond nitrogen reduction (shellfish) or watershed source control for long-term restoration of this system. As stated above, Sesachacha Pond, like Hummock Pond, has its water quality primarily controlled by the amount of flushing achieved during its spring openings. The variability introduced by the quality of openings makes temporal analysis difficult. However, it appears that Sesachacha Pond TN levels have clearly increased over the monitoring period (Figure 14b). The increase is significant (t test, p<0.05) with the initial years 2010-2013 (TN=0.671 mg/L) significantly lower than 2014-2017 (TN=0.933 mg/L), with the groupings determined by the quality of the openings. While the pond is again moving to historic low water quality levels, the high quality openings in 2010-2013 indicate that pond openings can play a primary role in restoring water and habitat quality within the pond (threshold = 0.600 mg/L), although this may have to be done in concert with other nitrogen management alternatives, e.g. shellfish, source reduction, etc. In contrast to Hummock Pond and Sesachacha Pond, Long Pond is open to tidal exchange, although somewhat restricted as seen in its mean salinity (2017 = 14 PSU; mean stations 5 & 6). Madaket Ditch provides a conduit for outflow of nutrient rich water from Long Pond and inflowing low nitrogen water from Madaket Harbor. Early on, the Nantucket Water Quality Monitoring Program reported a decline in TN levels potentially resulting from Town improvements to the landfill in the Long Pond watershed. Initially, it was not clear if the observed decline 2010-2013 would be sustained, continue to decline or return to previous (MEP) levels. It now appears that TN levels have declined and may be stabilizing at a lower level, likely between 0.80 and 0.60 mg/L (Figure 14c). However due to inter-annual variations which may be related to on-going activities at the landfill and/or ecological transitions within the pond itself, it is not yet clear what the “new” steady state TN level will be. However, continued monitoring should clarify this latter point within a few years, unless new nitrogen sources or sinks develop within the watershed. The large estuarine basins of Madaket Harbor and Nantucket Harbor both support high quality habitats consistent with their low TN and chlorophyll-a levels. The nearshore region of Madaket Harbor (stations 1-3) is the recipient for ebbing waters from Long Pond via Madaket Ditch. Temporal analysis indicates that TN levels at these nearshore stations has declined slightly over the monitoring period (Figure 14d). While there is some inter-annual variation in TN levels, the decline is statistically significant. At this point the only explanation available for this observed decline is that the TN load to 33 Madaket Harbor from Long Pond has been decreasing. As more information from the landfill becomes available it might be useful to the Town to re-run the MEP Watershed- Embayment Model for this system as previously mentioned above to verify the expected improvements to Hither Creek (sentinel station) and Madaket Harbor, as well as Long Pond itself. At present, it is important to determine the new steady state TN level in Long Pond, as it appears to be approaching the level set in the MassDEP/USEPA TMDL for this system. Similarly, the main basins of Nantucket Harbor are also showing a possible temporal decline in TN, although the amount is obscured by the inter-annual variability and the very small changes (Figure 14e). At present, the time-series changes cannot be demonstrated statistically and therefore only indicate that analysis should continue. However, it does not appear that TN levels are increasing. It should be noted that only a very small TN reduction was anticipated from the reconstruction of the jetties, but as additional planned sewering is undertaken, it should be possible to detect the TN reduction. As stated above, this temporal analysis is preliminary and is being undertaken to guide future analysis. 34 0.0 5.0 10.0 15.0 20.0 25.0 30.0 35.0 0.000 0.100 0.200 0.300 0.400 0.500 0.600 0.700 0.800 0.900 1.000 0 2 4 6 8 Total Chlorophyll a (ug/L)Total Nitrogen (mg/L)Hummock Pond 2010-2017 TN Total Chlorophyll a Figure 14a. Hummock Pond main basin annual averages for TN and total chlorophyll a from 2010, 2012-2017 (shown as year 0, 2, 3, 4, 5, 6, 7). No significant temporal trends were detected. Does not include the semi-isolated Head of Hummock Pond. y = 0.0474x + 0.6376 R² = 0.60 0.00 0.20 0.40 0.60 0.80 1.00 1.20 0.0 2.0 4.0 6.0 8.0 10.0 12.0 0 2 4 6 8 Total Nitrogen (mg/L)Total Chlorophyll a (ug/L)Sesachacha Pond Sta 1-4: 2010-17 Figure 14b. Sesachacha main basin annual averages for TN and total chlorophyll a from 2010, 2012-2017 (shown as year 0, 2, 3, 4, 5, 6, 7). Total nitrogen appears to have been increasing over the monitoring period as openings have declined. 2010-2013 (TN=0.671 mg/L) is significantly (p<0.05) lower than 2014-2017 (TN=0.933 mg/L). 35 y = -0.0062x3 + 0.0948x2 -0.498x + 1.6902 R² = 0.82 0.00 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00 0.0 5.0 10.0 15.0 20.0 25.0 0 1 2 3 4 5 6 7 8 Total Nitrogen (mg/L)Total Chlorophyll a (ug/L)Long Pond 2010 -2017 Total Chlorophyll a ug/L TN mg/L Figure 14c. Long Pond main basin annual averages for TN and total chlorophyll a from 2010, 2012-2017 (shown as year 0, 2, 3, 4, 5, 6, 7). Total nitrogen has declined over the monitoring period and appears to be stabilizing. TN = -0.0124x + 0.47 R² = 0.42 0.00 0.10 0.20 0.30 0.40 0.50 0.60 0.0 2.0 4.0 6.0 8.0 10.0 12.0 0 2 4 6 8 Total Nitrogen (mg/L)Total Chlorophyll a (ug/L)Madaket Hbr Sta 1-3: 2010 -17 Figure 14d. Nearshore Madaket Harbor main basins annual averages for TN and total chlorophyll a from 2010, 2012-2017 (shown as year 0, 2, 3, 4, 5, 6, 7). Total nitrogen appears to have been declining over the monitoring period. While the trend is significant (p<0.05), the variability makes an accurate determination of average annual decline difficult in this initial analysis. The offshore station is not included. 36 y = -0.0025x + 0.3708 R² = 0.07 0.00 0.05 0.10 0.15 0.20 0.25 0.30 0.35 0.40 0.45 0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 0 2 4 6 8 Total Nitrogen (mg/L)Total Chlorophyll a (ug/L)Nantucket Hbr Sta 1-7: 2010-17 Figure 14e. Nantucket Harbor main basins annual averages for TN and total chlorophyll a from 2010, 2012-2017 (shown as year 0, 2, 3, 4, 5, 6, 7). Total nitrogen appears to have been declining over the monitoring period, but the variability makes determination of the magnitude difficult at this time. The variability and small potential decline can be seen in the low R2. The offshore station is not included. Streams: Stream sampling in 2017 followed sampling completed in 2016 with the addition of one stream sampling location (WPH OUTLET, Figure 6). WPH Outlet was added by the Town of Nantucket as it is thought that a portion of the flow from the up- gradient bogs is discharged to West Polpis Harbor as depicted in Figure 6a. 2016 stream sampling locations were reduced from 6 stream locations to 3 (STA. 4, 4A and 6B), all of which discharge to Polpis Harbor. Stations 4 and 6B represent two distinct surface water inflows to Polpis Harbor with flow passing station 6B entering West Polpis Harbor and flow passing station 4 going to East Polpis Harbor from the up-gradient bogs, with the above mentioned caveat regarding station WPH OUTLET which may be directing a bit of cranberry bog flow to West Polpis Harbor. Station 4A (selected by the Conservation Foundation) is located up-gradient of station 4 and captures nutrient conditions prior to influence from a network of cranberry bogs. TN concentrations at the three discharge points measured in 2017 (stations 6B, WPH OUTLET, 4) were relatively high and consistent (1.107 mg/L, 1.037 mg/L and 1.021 mg/L respectively). By comparison, the TN levels in the 2 streams to Polpis Harbor sampled in 2016 ranged from 0.856 mg/L in Stream 4 to 0.922 mg/L in Stream 6B (Table 3a). In spite of the high TN concentrations in these 2 streams and the TN loads that these streams transport to Polpis Harbor, tidal flushing and dilution with lower concentration Nantucket Harbor waters is sufficient to maintain TN levels in the main 37 body of Nantucket Harbor at relatively low levels (Table 3a,b,c,d,e,f,g; Figure 6, 6a). The 2016 stream sampling sites were a subset of the streams sampled in 2010 with the results coupled with 2017 data and discussed below. It should be noted that the stream stations were not sampled in 2012, 2013 or 2014, however, with increasing interest in lowering TN concentrations in Polpis Harbor, in 2015 it was decided to re-establish sampling of streams discharging to this tributary sub-embayment and continue sampling these sites with the idea that in the future a detailed evaluation of stream related flows and loads to east and west Polpis Harbor would warranted. Average 2017 [2016, 2015, 2014, 2013, 2012, 2010] TN concentrations in East Polpis Harbor, 0.405 [0.400, 0.404, 0.378, 0.401, 0.438, 0.484] mg/L and West Polpis Harbor 0.429 [0.420, 0.422, 0.389, 0.385, 0.431, 0.419] appear to have been very stable from 2017-2012. These basins are fed by the high TN levels in Streams 4, WPH OUTLET and 6B and diffuse groundwater inflows and support TN levels slightly higher than the levels in the main Harbor, but still significantly lower than the levels in the streams (Table 2a, Figure 6, 6a). It should be noted that the two stations in Polpis Harbor (NAN- 5 {Polpis west} and NAN-6 {Polpis east}) do show essentially the same TN concentration compared to levels observed in 2016 and 2015. TN levels remain above the nitrogen threshold for these basins, although total pigment was still relatively low in 2017 and similar to levels measured in 2016. Total pigment at Polpis Station NAN-5 was slightly lower in 2017 compared to 2016 (4.82 ug/L vs. 5.80 ug/L) and levels at NAN-6 were slightly higher in 2017 compared to 2016 (6.51 ug/L vs. 4.61 ug/L). These values are consistent with the nearly equal TN concentrations observed in 2017 and 2016. Chlorophyll levels in 2015 were higher than 2014 possibly reflecting the slightly higher TN and warmer summer conditions in 2015 compared to 2014. Overall, TN concentration in Nantucket Harbor was the same in 2017 (0.353 mg/L) compared to 2016 and slightly lower in 2016 (0.354 mg/L) compared to 2015 (0.381 mg/L) and slightly higher compared to summer 2014 (0.324 mg/L). As such it is important to continue summer water quality monitoring and watershed based nutrient management and to provide a multi-year base for determining TMDL compliance as management actions are being implemented. Evaluation of the streams should be continued keeping stream volumetric flow and stream sampling such that nitrogen loads to Polpis Harbor can be monitored and related to the Polpis Harbor TN levels. Determining the coupling of stream inputs to Harbor TN levels may support development of a nitrogen management alternative for this basins. However, given the complexity of flow from the bogs seemingly split between east Polpis and west Polpis Harbor, a more detailed study of this surfacewater flow systems and its associated loads might be needed to refine any potential management action. Stream sampling in 2015, 2016 and 2017 included both nitrogen concentration and flow measurements and was included in the overall monitoring program to determine linkages, as they may exist, between stream loads and Polpis Harbor TN levels, particularly as related to the MEP TN threshold in Polpis Harbor (NAN-6 is considered the MEP sentinel station, with a TN threshold concentration of 0.355 mg/L for restoration). In 2017, samples were collected from 4 stations (stations 6B, WPH OUTLET, 4, 4A) on two distinct streams flowing into different parts of Polpis Harbor (e.g. east vs. west). This differs slightly from 2016 when samples were collected from a total of 3 stations in 2 streams (ST4, ST4A, ST6B) but in 2015 the same stations (ST4, ST6B) were sampled along with ST3 to gauge TN load discharging to Polpis Harbor. In 2017, station WPH OUTLET was added because it was suspected that a portion of the 38 flow from upgradient cranberry bogs was splitting towards west Polpis Harbor as opposed to passing by station 4 and all entering east Polpis Harbor. In 2016, ST3 was replaced by ST4A (upgradient of ST4) because there was little flow at ST3 in 2015 and no measureable flow in the summer of 2016 (though not checked consistently by the Town in 2016). Sampling at station 4A was continued in 2017, however, there is a possibility that this maybe discontinued in 2018 due to the limited flow passing through that stream sampling location. As in 2016, stream sampling in 2017 showed high TN concentrations at stations 4 and 4A (1.021 mg/L and 0.984 mg/L respectively) and higher than the same stations in 2016. By comparison, stream sampling in 2016 showed high TN concentrations at ST4 and 4A (0.856 mg/L and 0.776 mg/L respectively) but were lower than in 2015 (ST4 in 2015 = 1.060 mg/L), based on data presented in Table 2a,b,c. Interestingly, stream sampling site ST4 and ST6B were sampled once (June) in 2010 and showed TN concentrations of 1.200 and 2.139 mg/L respectively. The 2010 concentrations were consistent with the high concentrations observed in 2015 but in 2016 TN levels at both these stations (4 and 6B) were similar (0.856 mg/L and 0.922 mg/L) and lower than in 2015 or 2010. Similarly, in 2017 TN levels at both these stations (4 and 6B) were essentially the same (1.021 mg/L and 1.107 mg/L respectively). It should be noted that TN concentrations at WPH OUTLET were similar to measured concentrations at station 4, as would be expected (1.037 mg/L vs. 1.021 mg/L) since the flow passing WPH OUTLET is supposedly from the same up- gradient source, the cranberry bogs. The variation in TN levels from year to year may be associated with a combination of changes in long-term groundwater variations as well as cranberry bog management and warrants continued monitoring of stream flow and nutrient concentrations discharging to Polpis Harbor. Management of these flows and nutrient loads may provide a non-infrastructure approach to achieving the MassDEP/USEPA TMDL TN threshold for Polpis Harbor at the sentinel station (NAN-6). By measuring both the nutrient concentrations and the volumetric discharge the nutrient load can be determined. As in the previous year, Town of Nantucket staff measured the volumetric flow of water flowing at each sampling location in parallel with the water quality sample collection during the summer 2017 field season. The Town provided to CSP the critical stream flow values (m3/d) to be coupled with the parallel measurements of total nitrogen concentration data to calculate TN load (kg/day) from these streams to Polpis Harbor in summer 2017. The flow determined for each sampling day was then used to determine load for a representative month. Combining the high TN concentrations with relatively large flows measured in 2017 at ST4, WPH OUTLET and ST6B, it is clear that a large TN load is being transported to Polpis Harbor on a monthly basis, if there is sufficient flow. For the period June- October, the load passing through sampling location 4, WPH OUTLET and 6B was calculated to be 198 kg, 152 kg and 156kg respectively (based on values presented in Table G). It is important to note that given some of the large loads presented for winter and spring sampling dates as opposed to the lower loads during the summer when rainfall is typically much lower than in the winter and spring, a more robust quantification of flows and loads is warranted given the potential influence of these discharges on the sentinel station in Polpis Harbor. Given this first approximation of the TN loads entering Polpis Harbor via streams, it would clearly be worth continuing measuring flow and nitrogen sampling in coming years of monitoring, particularly since flows and loads in 2017 and 2016 appeared higher than in 2015. A perfect comparison is difficult as the sampling periods were not exactly the same in these initial years. 39 Table G. 2017 flows and nitrogen and phosphorus loads determined for two streams at sampling stations 4 and 6B. Station 4A is upgradient of station 4 in the same stream. Date Sample ID Measured TN Load TN Load TP Load TP Load Representative Flow Month (m3/d)(kg/day)(kg/month)(kg/day)(kg/month) 2/8/2017 ST4 343 0.2366 6.63 0.0127 0.36 February 3/27/2017 ST4 969 0.7292 22.60 0.0364 1.13 March 4/27/2017 ST4 2911 1.9522 58.57 0.1272 3.82 April 5/23/2017 ST4 ND ND ND ND ND May 6/12/2017 ST4 1584 1.6539 49.62 0.0930 2.79 June 7/5/2017 ST4 171 0.1499 4.65 0.0060 0.19 July 8/15/2017 ST4 3743 3.2070 99.42 0.0981 3.04 August 9/11/2017 ST4 685 0.7796 23.39 0.0422 1.27 September 10/24/2017 ST4 580 0.6899 21.39 0.0963 2.99 October 2/8/2017 ST4A 70 0.0627 1.75 0.0006 0.02 February 3/27/2017 ST4A 159 0.0915 2.84 0.0005 0.02 March 9/11/2017 ST4A 710 1.0488 31.46 0.0279 0.84 September 2/8/2017 ST6B 159 0.1037 2.90 0.0035 0.10 February 3/27/2017 ST6B 489 0.2556 7.92 0.0087 0.27 March 4/27/2017 ST6B 856 0.5221 15.66 0.0243 0.73 April 5/23/2017 ST6B 1737 3.4664 107.46 0.0551 1.71 May 6/12/2017 ST6B 208 0.4185 12.56 0.0086 0.26 June 7/5/2017 ST6B 1798 2.0030 62.09 0.1830 5.67 July 8/15/2017 ST6B 0 0.0000 0.00 0.0000 0.00 August 9/11/2017 ST6B 1676 1.4075 42.22 0.0645 1.94 September 10/24/2017 ST6B 1121 1.2595 39.05 0.3695 11.45 October 5/23/2017 WPH OUTLET 5811 5.1762 160.46 0.2565 7.95 May 6/12/2017 WPH OUTLET 1182 1.3769 41.31 0.0625 1.88 June 8/15/2017 WPH OUTLET 976 0.7176 22.25 0.0248 0.77 August 9/11/2017 WPH OUTLET 1994 2.2316 66.95 0.1279 3.84 September 10/24/2017 WPH OUTLET 612 0.6896 21.38 0.0947 2.94 October 40 Table H. 2016 flows and nitrogen and phosphorus loads determined for two streams at sampling stations 4 and 6B. Station 4A is upgradient of station 4 in the same stream. 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 Table I. 2015 flows and nitrogen loads determined for three streams. Stations 4 and 6B were also sampled in 2016. Measured TN Load TN Load 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 41 The effect of stream inputs requires further analysis, because while flows and loads from stream sites ST4 and 6B were measurably higher in 2017 compared to 2016 and 2015, TN concentrations at stations Nan-5 and Nan-6 in Polpis Harbor were not significantly different from concentrations measured in 2016. Additionally, TN levels were lower in 2016 compared to 2015. Moreover, in regard to stream sampling location ST4 and ST4A (up-gradient of ST4 but selected by the Conservation Foundation to represent water before influence of the bogs), for the months of February and March in 2017 where there was data for both stations, TN load at ST4A compared to ST4 ranged from 12% to 25% (2016 TN load at ST4A compared to ST4 ranged from 12% to 38% of the measured load at ST4) indicating substantial “pick-up” of groundwater occurs between these stations. Equally important, in 2017 TN load for the period June through October from ST4 accounted for 27% more load when compared to load leaving ST6B (June- October load at ST4 = 198 kg vs. ST6B = 156 kg). Additionally, load from WPH OUTLET which enters west Polpis Harbor along with loads from ST6B is an equally significant input to that portion of the Polpis Harbor system (June-October load at WPH OUTLET = 152 kg vs. ST6B = 156 kg). The WPH OUTLET load maybe greater than that measured at STA6B simply because there was no data for July from the WPH OUTLET location. As previously mentioned in 2016, it would be important to more accurately quantify flows and loads from WPH OUTLET, ST4 and the up-gradient bog system as this surfacewater source may be the main driver of TN levels at Nan-5 and 6 in Polpis Harbor. Given these complexities, a detailed investigation of flow and loads throughout the network of bogs up-gradient of ST4 and WPH OUTLET is warranted to refine management of nutrients entering Polpis Harbor from its associated sub- watershed. Further study would be helpful to determine whether the cranberry bogs will benefit from best management practices to limit their influence in contributing nitrogen to Polpis Harbor. As such, it may be preferable that such an investigation be completed by the bog owner: The Nantucket Conservation Foundation in collaboration with the bog manager who would have detailed information on bog operating practices critical to ensure sample timing and bog management practices are coordinated. Additional estuarine stations (ORS-2,3,4,5,6) were added in 2015 to the sampling stations in Nantucket Harbor and Madaket Harbor (ORS-1) specifically to monitor water quality in the vicinity of potential sites for deployment of oyster aquaculture. A subset of the 2015 stations (ORS-2,4,6) were sampled again in 2016 and 2017. These stations had never been sampled prior to 2015 so it is not possible to compare 2017, 2016 and 2015 results to past years, however, 2017, 2016 and 2015 results for stations ORS- 2,4,6 can serve as the beginning of establishing a baseline for gauging changes in future years. 2017 TN levels at ORS-2,4,6 (0.329 mg/L, 0.414 mg/L, 0.460 mg/L) were very similar to 2016 levels (0.339 mg/L, 0.382 mg/L, 0.472 mg/L) and lower then in 2015 at ORS-2,4,6 (0.338 mg/L, 0.415 mg/L, 0.551 mg/L). Station concentrations are generally consistent with the water quality from nearby long term monitoring stations. In the future a detailed interpretation of the data collected at these stations will be possible once more data becomes available. 42 Table 2a. Summary of Stream Water Quality Parameters (ST4,ST4A,ST6B) and stations associated with potential oyster aquaculture locations (ORS,2,4,6), 2017 Nantucket Sampling Program. STA4A was added in 2016 to further interpret flow and load results from STA4, however, in 2017 there were dates when there was no flow at STA4A. Lab Avg.Avg.Avg.Avg.Avg.Avg.Avg.Avg.Avg.Avg.Avg.Avg.Avg.Avg. Date Location Sample ID Salinity PO4 TP NH4 Nox DIN DON TDN POC PON TON TN Chla Phaeo Total Pig ppt (mg/L)(mg/L)(mg/L)(mg/L)(mg/L)(mg/L)(mg/L)(mg/L)(mg/L)(mg/L)(mg/L)(ug/L)(ug/L)(ug/L) 2/8/2017 NANTUCKET STREAMS ST4 0.10 0.037 0.051 0.007 0.005 0.012 0.629 0.549 0.777 0.050 0.679 0.691 1.35 0.93 2.280 3/27/2017 NANTUCKET STREAMS ST4 0.10 0.038 0.055 0.012 0.009 0.020 0.703 0.620 0.364 0.029 0.732 0.753 1.01 0.14 1.153 4/27/2017 NANTUCKET STREAMS ST4 0.10 0.044 0.064 0.011 0.005 0.016 0.631 0.555 0.282 0.023 0.655 0.671 0.53 0.79 1.325 5/23/2017 NANTUCKET STREAMS ST4 0.10 0.036 0.063 0.007 0.014 0.020 0.967 0.846 0.808 0.046 1.013 1.033 0.77 1.31 2.087 6/12/2017 NANTUCKET STREAMS ST4 0.10 0.059 0.086 0.016 0.014 0.029 0.958 0.846 0.736 0.057 1.015 1.044 1.19 0.99 2.184 7/5/2017 NANTUCKET STREAMS ST4 0.10 0.035 NS 0.011 0.004 0.015 0.806 0.704 0.629 0.039 0.845 0.875 0.63 0.89 1.522 8/15/2017 NANTUCKET STREAMS ST4 0.10 0.026 0.053 0.007 0.002 0.010 0.742 0.644 1.649 0.095 0.837 0.857 3.05 0.03 3.073 9/11/2017 NANTUCKET STREAMS ST4 0.10 0.062 0.085 0.021 0.002 0.023 1.079 0.945 0.569 0.036 1.115 1.138 1.53 0.46 1.987 10/24/2017 NANTUCKET STREAMS ST4 0.10 0.166 0.227 0.007 0.006 0.013 1.142 0.990 0.505 0.035 1.177 1.190 0.02 0.36 0.374 2/8/2017 NANTUCKET STREAMS ST4A 0.10 0.009 0.018 0.011 0.009 0.020 0.851 0.747 0.450 0.028 0.879 0.899 0.09 2.68 2.767 3/27/2017 NANTUCKET STREAMS ST4A 0.10 0.003 0.012 0.011 0.008 0.019 0.514 0.457 0.451 0.043 0.556 0.575 0.24 0.33 0.566 9/11/2017 NANTUCKET STREAMS ST4A 0.10 0.039 0.079 0.025 0.009 0.034 1.387 1.219 0.533 0.056 1.444 1.478 0.10 0.85 0.949 2/8/2017 NANTUCKET STREAMS ST6B 0.10 0.022 0.030 0.010 0.007 0.017 0.603 0.531 0.557 0.032 0.635 0.652 0.39 0.55 0.942 3/27/2017 NANTUCKET STREAMS ST6B 0.10 0.018 0.027 0.019 0.037 0.055 0.444 0.428 0.400 0.023 0.467 0.522 0.26 0.20 0.458 4/27/2017 NANTUCKET STREAMS ST6B 0.00 0.028 0.040 0.013 0.008 0.021 0.553 0.492 0.664 0.036 0.589 0.610 0.50 0.82 1.316 5/23/2017 NANTUCKET STREAMS ST6B 0.00 0.032 0.057 0.013 0.015 0.028 1.930 1.679 0.672 0.037 1.967 1.996 0.55 1.35 1.894 6/12/2017 NANTUCKET STREAMS ST6B 0.00 0.041 0.062 0.016 0.015 0.031 1.927 1.679 1.124 0.054 1.981 2.013 0.65 0.95 1.600 7/5/2017 NANTUCKET STREAMS ST6B 0.00 0.102 NS 0.003 0.005 0.008 0.581 0.505 13.568 0.516 1.097 1.114 0.63 2.03 2.667 8/15/2017 NANTUCKET STREAMS ST6B 0.10 0.025 0.068 0.007 0.003 0.010 0.355 0.313 1.457 0.067 0.422 0.442 14.21 0.03 14.232 9/11/2017 NANTUCKET STREAMS ST6B 0.00 0.039 0.054 0.016 0.003 0.019 0.787 0.691 0.640 0.033 0.821 0.840 0.04 0.38 0.416 10/24/2017 NANTUCKET STREAMS ST6B 0.00 0.330 0.525 0.019 0.004 0.023 1.063 0.931 1.009 0.038 1.101 1.124 0.00 0.90 0.901 5/23/2017 NANTUCKET STREAMS WPH OUTLET 1.00 0.044 0.074 0.006 0.007 0.013 0.823 0.716 0.902 0.055 0.878 0.891 0.30 1.29 1.590 6/12/2017 NANTUCKET STREAMS WPH OUTLET 2.00 0.053 0.102 0.018 0.013 0.031 1.074 0.947 0.908 0.060 1.134 1.165 1.99 0.99 2.975 8/15/2017 NANTUCKET STREAMS WPH OUTLET 0.70 0.025 0.047 0.019 0.004 0.023 0.627 0.557 1.079 0.062 0.689 0.735 0.60 0.03 0.623 9/11/2017 NANTUCKET STREAMS WPH OUTLET 0.10 0.064 0.087 0.020 0.006 0.026 1.052 0.924 0.707 0.041 1.093 1.119 0.20 0.75 0.958 10/24/2017 NANTUCKET STREAMS WPH OUTLET 0.10 0.155 0.216 0.011 0.008 0.019 1.063 0.927 0.793 0.046 1.109 1.127 0.06 0.70 0.762 43 Lab Avg.Avg.Avg.Avg.Avg.Avg.Avg.Avg.Avg.Avg.Avg.Avg.Avg.Avg. Date Location Salinity PO4 TP NH4 Nox DIN DON TDN POC PON TON TN Chla Phaeo Total Pig Sample ID ppt (mg/L)(mg/L)(mg/L)(mg/L)(mg/L)(mg/L)(mg/L)(mg/L)(mg/L)(mg/L)(mg/L)(ug/L)(ug/L)(ug/L) 5/17/2017 Old North Wharf - Oyster ORS2 31.90 0.009 NS 0.016 0.003 0.019 0.213 0.231 0.450 0.083 0.296 0.314 2.08 0.87 2.95 6/14/2017 Old North Wharf - Oyster ORS2 30.30 0.004 NS 0.013 0.001 0.014 0.220 0.234 0.283 0.049 0.269 0.283 3.98 0.75 4.73 7/12/2017 Old North Wharf - Oyster ORS2 NS 0.023 NS 0.035 0.003 0.038 0.206 0.244 NS NS NS NS NS NS NS 8/10/2017 Old North Wharf - Oyster ORS2 31.00 0.014 NS 0.014 0.001 0.015 0.262 0.277 0.296 0.043 0.305 0.334 1.87 0.03 1.89 9/25/2017 Old North Wharf - Oyster ORS2 29.70 0.021 NS 0.063 0.013 0.076 0.242 0.318 0.302 0.052 0.294 0.370 1.59 0.81 2.40 5/17/2017 Shimmo - Oyster ORS4 30.70 0.009 NS 0.014 0.012 0.027 0.387 0.414 0.296 0.049 0.436 0.463 1.02 0.87 1.89 6/14/2017 Shimmo - Oyster ORS4 29.70 0.012 NS 0.022 0.007 0.029 0.284 0.313 0.318 0.059 0.343 0.372 1.55 1.19 2.74 7/12/2017 Shimmo - Oyster ORS4 30.10 0.019 NS 0.035 0.003 0.038 0.257 0.295 0.326 0.054 0.311 0.386 1.57 1.50 3.07 8/10/2017 Shimmo - Oyster ORS4 30.30 0.017 NS 0.014 0.003 0.017 0.462 0.479 0.306 0.051 0.514 0.548 1.02 0.35 1.37 9/25/2017 Shimmo - Oyster ORS4 29.10 0.027 NS 0.047 0.027 0.074 0.225 0.299 0.310 0.050 0.276 0.350 1.30 0.76 2.06 5/17/2017 Polpis - Oyster ORS6 30.20 0.009 NS 0.011 0.000 0.011 0.230 0.241 0.417 0.074 0.304 0.315 1.56 0.86 2.43 6/14/2017 Polpis - Oyster ORS6 30.00 0.009 NS 0.010 0.001 0.011 0.322 0.333 0.306 0.054 0.376 0.387 1.68 1.07 2.75 7/12/2017 Polpis - Oyster ORS6 30.20 0.021 NS 0.046 0.006 0.052 0.393 0.445 0.542 0.101 0.494 0.598 3.33 0.90 4.23 8/10/2017 Polpis - Oyster ORS6 30.10 0.020 NS 0.026 0.002 0.028 0.307 0.335 0.344 0.061 0.368 0.424 0.38 0.34 0.73 9/25/2017 Polpis - Oyster ORS6 28.70 0.027 NS 0.069 0.011 0.080 0.271 0.351 0.529 0.079 0.350 0.430 1.82 1.52 3.35 44 Table 2b. 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 45 Table 2c. 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 46 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- 2017) using the summer monitoring results. The Index scores were calculated in 2 ways, one which included the low dissolved oxygen for each year in the index ("with DO", Table 8) and one which excluded the oxygen metric ("without DO", Table 9). The reason for this dual approach is that in some estuaries, such as those on Nantucket, there are only periodic depletions in bottom water dissolved oxygen, generally related to meteorological events acting on nutrient enriched basins. While these short-term depletions have important ecological consequences, they are difficult to capture in programs that sample 4 or 5 dates per summer. In these cases, inclusion of the oxygen can bias the Index upwards (i.e. higher quality) because of the greater probability of capturing high versus low oxygen events (i.e. missing periodic low oxygen events). This bias was found in the previous analysis of the 2010 dataset, as well as for other estuaries in s.e. Massachusetts. However, this is not always the case and there was no substantive difference between the "with DO" and "without DO" Index scores based on the 2013 and 2014 data and again in 2016 and 2017, 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). Further analysis of the with DO and without DO index values for all stations and monitoring years indicates that there is very little difference in the determined index value between the methods (RPD <10%). The exception was in Miacomet Pond and Head of Hummock Pond which have significant DO depletions in some years and therefore higher variability between the methods (RDP up to 20%). Given that inclusion of oxygen data did not generally change the bay health rank the with DO index is generally used, but both approaches are developed each year and presented herein. For the present analysis the standard Index (with DO) was used for assessment and the Health Status was determined for each site based on the data collected during the sampling events. The ranges of Index scores that fall within a particular Health Status determination are given at the bottom of both Tables 7 and 8 with the Index values and description for each monitoring station. Figures 20-24 show the distribution of Health Status throughout each estuary based on each of the 7 years of monitoring (2010, 2012- 2017). 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 47 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: Color Health Status Blue High Quality Blue/Yellow High-Moderate Yellow Moderate Yellow/Red Moderate/Fair Red Fair/Poor The integrated water quality scores, as represented by the Index were generally consistent among all 7 years of monitoring. Although change at some sites was observed, change was gradual and large inter-annual changes were typically related to major management actions. This relative stability is typical as nutrient related health does not generally change rapidly unless a significant alteration has occurred to the watershed nitrogen loading or to tidal flushing of a basin (e.g. Hummock Pond, Long Pond). However, 3 systems do appear to show a potential shift in nitrogen related health over the past 7 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 2017 continued to support a high level of nutrient related water quality. It has been the more enclosed basins of Hither Creek and Long Pond with their reduced tidal flushing that have had nitrogen impairment problems. Water quality generally changes gradually, unless there has been a major change in loading or flushing. Within the Madaket Harbor/Long Pond watershed there has been a significant change in the nitrogen sourced at the Town Landfill. The Landfill has recently been undergoing management actions that reduce nitrogen loading to the groundwater, hence to upper Long Pond. It appears that the long-term gradual reduction in TN levels within the upper portions of this complex estuary is consistent with a lowering of watershed nitrogen loading. Over the 7 years of monitoring, Hither Creek (Station 1), which receives discharge from Long Pond via Madaket Ditch, has consistently supported the poorest “health” status within the Madaket Estuary (Table 8, 9, Figure 20). Hither Creek is clearly nitrogen enriched and showing continuing impairment based on a variety of parameters. However, over the past 7 years the Index indicates that this basin has improved slightly each year, going from fair-poor water quality and improving in a step-wise manner to moderate water quality since 2014. The exception was 2017 where TN levels rose, but stayed within the range that has developed over the past 4-5 years, this variability is expected to be reduced in coming years as the system reaches a new equilibrium with the new lower landfill TN loading rate. The main basin of Madaket Harbor is showing relatively high water quality in each year but also shows a possible improvement from 2010 to 2012 and has been generally stable at high water quality in more recent samplings. It appears that Station 2, near the outlet to Hither Creek can receive low quality waters on the ebb tide from Hither Creek 48 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 7 year positive trend in health index is at least partially the result of the reduced loading from the landfill to upper Long Pond and an improvement in the ebbing waters through Madaket Ditch. This trend is consistent with the upper basin feeding Madaket Ditch. In 2014-2017 the previously observed gradient in water quality metrics between the 2 Long Pond stations is only periodically detectable, lessening concern over a potential tidal restriction. While a further analysis of the mechanism underlying this periodic gradient would be useful, it is not needed at this time, tracking the phenomenon through the on-going monitoring program should be sufficient. If the improvement in Hither Creek becomes stabilized at the lower end of its range (0.8 – 0.6 mg/L), it is possible that the TMDL for Madaket Harbor may require somewhat less nitrogen load reduction, making the success of other nitrogen management actions (other than associated with the landfill and any needed septic system work in Madaket) more certain. However, at this point it is likely that additional nitrogen management will be required to meet the TMDL in Hither Creek, although it appears the reduced load discharging from Madaket Ditch has resulted in somewhat lower TN levels already. 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 20). Unlike Madaket Harbor which is marine, Long Pond is a brackish water system resulting from mixing of groundwater inflows and salt water entering through its restricted tidal channel. Long Pond’s Bay Health scores for both stations (5 & 6) in the 7 years of monitoring (2010, 2012-2017) 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, 2016 and 2017 were almost half that of historical and 2010 measurements although they still show significant inter-annual variations. While continued monitoring will determine the final level of improvement, it does appear that the reduction in N loading is occurring with beneficial effects. However, even if TN levels stabilize at 2016 levels, the TN is still slightly higher than needed for restoration. Although improved in the past 3 years, the basin still supports reduced water 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 2012-2017 compared to 2010 and in the MEP threshold analysis (see analysis and 49 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 coming monitoring seasons should provide the needed information to determine if the system will stabilize at these lower levels and allow determination if additional nitrogen source reduction is needed to meet the target in the MassDEP/USEPA TMDL. 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 21). Wauwinet basin (station 3) had the highest average total nitrogen values for the Harbor System in 2013 (0.415 mg/L) and 2015 (0.436 mg/L) consistent with its designation as the surrogate for the sentinel station for the main basin and its documented past eelgrass loss. It should be noted that in summer 2016, SMAST 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 2017 saw a slightly lower TN level at station NAN-2A (0.368 mg/L). Summers 2017 & 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 and 2017 again higher levels, clearly these blooms need to be tracked. However, other activities associated with the Harbor (additional sewer hookups, jetty improvement and oyster aquaculture) should result in even lower TN and chlorophyll levels and reduce the likelihood of large phytoplankton blooms in the future. A similar pattern was seen in the enclosed sub-basins of Polpis Harbor (East and West) as in the main basins of Nantucket Harbor. Polpis Harbor basins which after showing moderate impairment in 2010 and 2012 have been showing only low to moderate impairment in recent years, suggesting some improvement over historic conditions. As in Wauwinet, Polpis Harbor showed 2017 & 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 and linkages to stream nitrogen discharges. Polpis Harbor did not show a phytoplankton bloom in 2015 and supported only moderate-low phytoplankton biomass in 2015,2016 and 2017 (average <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, but approaching, its TMDL threshold, as is also the case for Polpis Harbor. Equally important, although variable, it appears that slight positive changes have been occurring in recent years. 50 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. However, with limited openings in 2014-2017, TN has risen and has returned to near historic levels, ~0.9 mg/L, associated with significantly impaired conditions. It appears that these changes relate to the quality of the pre-summer opening. Given the 2010-2013 period when robust openings occurred, it appears that a solid opening program has the capability to improve the water quality metrics pond-wide to levels near the TMDL nitrogen threshold. Based upon the Index alone, changes in water quality in Sesachacha Pond over the 2010-2013 period were stabilized at moderate impairment of this estuary, with more recent monitoring 2015-2017 seeing a trend toward poor water quality conditions (Figure 22) as TN levels have risen. Additional higher level assessment of Sesachacha Pond initiated based on the 2010 monitoring results was conducted and confirmed that the pond was improving by 2013, but was impaired in 2014 consistent with the monitoring results. The 2015-2017 data underscores the reversal of improvement with phytoplankton biomass (as chlorophyll) averaging >10 ug/L at all stations over the summer of 2017 and 2015 and 6-10 ug/L in 2016, consistent with nitrogen enrichment. The high chlorophyll values are consistent with the high TN values in 2014-2017. 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 51 watershed nutrient inputs have resulted in moderate to poor nutrient related water quality throughout the pond, with poor water quality conditions the present norm (2005- 2007, 2010, 2012, 2013, 2014, 2015). Unfortunately, in 2016 the pond appears to have had lower water quality in its upper and mid reaches than in previous years, although the lower basin did not show this inter-annual variation. Similarly, in 2017 water quality declined further throughout most of the estuary, including the lower basin. This resulted from the poor spring 2017 opening which is reflected in the very low salinities throughout summer 2017 (3.5 PSU). There is generally a small gradient in water quality with moderate to poor conditions near the ocean and poor conditions in the uppermost basins, but this collapsed to generally poor water quality throughout the system in 2017 (Figure 23). 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 2017 & 2016 showed levels ~15 ug/L. This basin appears to have been artificially connected to the adjacent estuary and is the recipient of much of the freshwater inflow. It is one of the most highly eutrophic basins within the Town of Nantucket. Due to the restricted tidal exchange even the lower basin of Hummock Pond supports moderate to high average chlorophyll levels ~10 ug/L (2010, 2012, 2015). All of the metrics are consistent with a nutrient impaired basin in all years. It should be noted that the lower third of the Hummock Pond Estuary is currently supporting impaired benthic animal habitat even though conditions are the "best" in the overall impaired system. Based upon the monitoring results it is clear that the nutrient related health of Hummock Pond is significantly related to the success of its periodic openings. As a result, the Town and Nantucket Land Council undertook an analysis to refine the opening protocol and gauge its effectiveness. The April 2013 opening was the first “experimental” opening and it appeared to result in significant loss of TN and inflow of salt water. The individual metrics and the Health Index for summer 2014 and 2015 appear to support that tidal flushing was improved as nutrient related health was highest in 2014 and 2015 of the years monitored. It also appears that the continued successful inlet openings from April 2014 into 2015 have resulted in additional improvements in water quality from 2014 to 2015, with 2015 showing the lowest TN levels in records back to 2005, although it is still above its threshold value to support high quality habitat. Unfortunately, this pattern was not seen in the 2017 & 2016 water quality data, which showed further decline in the upper and mid reaches, and even the lower basin. This opening program and associated monitoring around the openings and in the summer will be used to set metrics for a “successful” opening, to produce a simplified assessment protocol for opening success and to document and further refine the opening protocol for the Town’s on-going program. To date this joint effort has shown the potential for significant benefits to Hummock Pond water quality and associated natural resources at low cost to the Town. Miacomet Pond Miacomet Pond is a closed coastal salt pond that is rarely (over a decade ago) opened to the ocean to flush out nutrients and organic matter on the ebb tide and receive low nutrient saline waters on the flood tide. As a result of the lack of tidal flow and continuous groundwater inputs, the pond is presently freshwater, with salinity levels in each of the past 6 years of monitoring of <0.5 ppt, reaching a low of 0.1 ppt, 2015-2017. The present non-tidal state and extent of watershed nutrient inputs has resulted in a 52 decline in nutrient related water quality throughout the pond for both nitrogen and phosphorus, with poor water quality and habitat impairment the present norm (Figure 24). This can be seen, for example, in the high chlorophyll levels (2010: 12-50 ug/L); 2012: 10-20 ug/L; 2013: 20-26 ug/L; 2014: 23-70 ug/L; 2015: 38-53 ug/L) several times greater than the levels found in the high quality basins of Nantucket and Madaket Harbors with 2017 and 2016 also high (mean = ~14 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 more typical levels in 2016 and 2017. 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 over-wash in the future due to climate change related storm intensification and sea level rise, it may be necessary for management to create both a nitrogen and a phosphorus budget for this system and to conduct short-term incubations to determine which nutrient is controlling pond health under present and varying salinity conditions. None-the-less, phosphorus should be a part of pond management, with phosphorus limitation to phytoplankton growth throughout Miacomet Pond in 2017 and 2016, although only for the middle and lower pond in 2015. It is also important to note that orthophosphate concentrations are quite low in the main basin (MP-1, MP-2) generally <0.2 uM, such that adding phosphorus to this basin in mid-summer would likely stimulate phytoplankton growth. In contrast, the uppermost reach generally supports 2x-3x higher phosphate levels. It is likely that regions of the pond may be sensitive to both nitrogen and phosphorus, such that overall both nutrients need to be monitored and considered for management of Miacomet Pond, although phosphorus management is clearly needed at this time. Another challenge in managing Miacomet Pond is that it will be difficult for the Pond to maintain itself as a purely freshwater system as storm over-wash and rising sea level (as well as increasing storm intensity and frequency related to climate change) will tend to periodically cause seawater intrusion into its lower basin. An analysis of future conditions for Miacomet Pond as sea level rises may be in order in the near future, as remediation is considered. But at present the system is a highly nutrient impaired aquatic system with poor water quality. It would be prudent for the Town to continue the development of a management plan that takes into account not only the nutrient related impairment of Miacomet Pond, but also accommodates the likely shifting between fresh and salt water over the long term. Recommendations for Future Monitoring (2018) (1) As mentioned in previous years summaries of estuarine water quality across Nantucket, due to the critical importance of dissolved oxygen to the ecological health of an estuarine basin, additional data should be collected using high frequency automated sensors when the low frequency sampling of the monitoring program suggests that a problem may exist in a specific basin. At this point, Polpis Harbor and Wauwinet basin in Nantucket Harbor should be considered for this analysis at some time in the future (e.g. summer 2018) as well as Hummock Pond and Miacomet Pond. It may also be timely to complete a higher level nutrient limitation assessment of Miacomet Pond (if one 53 hasn't already been completed) as that large “salt pond” has been transitioning to a freshwater ecosystem and has been showing consistently poor water quality and low trophic status indicative of an impaired habitat. However, procedural steps should also be implemented to strengthen the oxygen data base from the on-going monitoring program. In addition, Long Pond appears to be maintaining a lowering of its nitrogen levels over the past 3 years (even though 2017 TN levels are slightly higher than 2016), since the MEP full assessment of ecological health. At present, it appears that the Town activities at the Landfill have lowered the annual nitrogen input from this source lowering TN levels in Long Pond to 0.6 – 0.8 mg/L. However, it is not known how long it will take for the full reduction to occur or what the new TN load from the landfill will be. 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 and will hopefully be reflected in the results of the recently completed (November 2017) benthic infaunal survey. 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. This could potentially be achieved by re-running the MEP water quality model with updated landfill loads based on the remediation work that has occurred to date. The monitoring results from 2012 - 2017 appear to show a significant reduction in TN over historical conditions and 2010, however, there is still significant inter-annual variability as seen in the 2014- 2017 results. As previously mentioned, 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, while the TN levels in 2017 are a little higher, (Long6 nearly the same 2017 to 2016, Long5 higher 2017 to 2016), the levels as still well below the 2010-2014 average TN. Considering, the TN levels in 2016 showed 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}), it would be appropriate to re-run the MEP model with new landfill loads to ascertain if the model predictions align with water quality observations. At present, TN levels remain the lowest on record. The landfill analysis would allow prediction of how low TN levels should decline and should help guide the timing of an ecological assessment focusing on if TMDL compliance has been achieved. 2017 infaunal survey results should be compared to 2003 results obtained under the MEP to determine if species have significantly in line with observed lowering of nutrient concentrations 2015-2017 (2) Results from monitoring streams discharging to Nantucket Harbor (specifically Polpis Harbor) for which sampling was conducted only in 2015, 2016 and 2017 indicated 54 that the nitrogen load from these streams can be significant relative to TN levels within Polpis Harbor, but that flow is highly seasonal due to lower stream flow volumes in summer. With increasing interest in lowering TN concentrations in Polpis Harbor to meet the MEP established TN threshold, it is appropriate to extend stream sampling into the 2018 sampling season given the high concentrations of total nitrogen observed in 2017, 2016 and 2015 that are discharging to this tributary sub-embayment. Moreover, given the complexity of the flow leaving the cranberry bogs up-gradient of station 4 and the apparent split of the flow between east and west Polpis Harbor, a detailed flow and load investigation should be undertaken. This is particularly important as the load entering west Polpis Harbor past station WPF OUTLET appeared to be nearly equal to the load entering the same portion of the system past station 6B (however sources of load to both discharge points are different). 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. Moreover, given the seasonal variations, more than one streamflow measurement and sampling is warranted in order to more accurately characterize the flow and load for a given month. 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 2017 and 2016 compared to 2015 and it may be possible to develop nitrogen reduction alternatives to lower these stream discharges. The stream monitoring coupled to the estuarine monitoring will allow a determination of the linkage of stream discharge to TN levels in Polpis Harbor. Moreover, in regard to stream sampling location ST4 and ST4A, TN load at ST4A compared to ST4 in 2017 ranged from ~12% to 25% (2016, ~12% to 38%) of the measured load at ST4, clearly indicating a load difference with associated concentrations being measurably higher at station 4A (1.478 mg/L) compared to station 4 (1.021 mg/L). In 2016 the average TN concentrations were fairly similar (0.856 versus 0.776 mg/L). It is clear that there is significant “pick-up” of flow and load to the stream occurring between the upper and lower station, which dominates the stream discharge to the Harbor. The source of this nitrogen should be investigated. In 2017 TN load for the period June through October from ST4 accounted for 27% more load when compared to load leaving ST6B (June- October load at ST4 = 198 kg vs ST6B = 156 kg). Additionally, load from WPH OUTLET which enters west Polpis Harbor along with loads from ST6B is an equally significant and possibly greater input to that portion of the Polpis Harbor system (June- October load at WPH OUTLET = 152 kg vs ST6B = 156). The WPH OUTLET load maybe greater than that measured at STA6B simply because there was no data for July from the WPH OUTLET location. The initial data from 2016 indicated that TN load from ST4 accounts for 61% to 70% of the combined load from streams ST4 and ST6B. Given the 2017 and the 2016 results, it would be important to determine the watershed areas contributing flow and load to ST4, ST6B and WPH OUTLET and to a lesser extent from the upgradient bog system relative to reducing loads to Polpis Harbor. A more detailed investigation is warranted in collaboration with the bog owner. (3) Miacomet continues to show poor trophic conditions, high TN concentrations (though slightly lower in 2017 at stations MP-1 and MP-2) through its basins (stations 1, 2, and 3 in 2017: 0.641, 0.584, 0.909 mg/L, 2016: 0.772, 0.669, 0.783 mg/L, respectively). Although TN levels were slightly lower in 2017 at the middle and lower 55 stations and lower in 2016 than in 2015, 2017 levels are still indicative of a highly enriched condition, as also indicated by the high total pigment concentrations (CHLA + pheophytin) in 2017 (10-20 ug/L) and 2016. In light of yet another year of poor water quality in Miacomet Pond, nitrogen and phosphorus budgets should be developed for Miacomet Pond and a quantitative analysis of N versus P as the driving nutrient of eutrophication (if this has not been completed to date). Assessing the degree to which Miacomet Pond is N or P limited and if the limitation tends more to one or the other constituent seasonally will be critical to developing an effective management plan for this freshwater system. This information can be used to directly support development of management options for improving the health of the pond. 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 2018. 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 as well as completing controlled biotests (bottle tests, mesocosm experiments) with different levels of P and N amendments to the natural phytoplankton community. (4) Pond Openings and Linkage to Water Quality. Hummock Pond appears to have its nutrient related health significantly controlled by the success of its periodic openings. As a result, the Town and Nantucket Land Council undertook an analysis of openings in 2013-2014 to refine the opening protocol and gauge its effectiveness. Critical elements of the protocol were described in a technical memorandum developed by the Coastal Systems Program which summarized two openings that were monitored to gauge effectiveness. The opening protocol developed from this detailed work should continue to be rigorously implemented as monitoring clearly shows that if specific conditions are taken into consideration during a given opening, the ensuing opening tends to be effective and have a clear positive impact on water quality. To date Hummock Pond water quality has been shown to significantly improve under the revised opening protocol by the Town. However, poor openings in 2017 have negated those improvements. Even so, the monitoring indicates that both Sesachacha and Hummock Ponds respond rapidly to changes in the level of annual flushing. It appears that only ~3 years of good flushing conditions can significantly improve pond water and habitat quality. It also appears that pond openings may have to be coupled with other nitrogen management alternatives to provide sufficient and long-lasting restoration. Monitoring of the pond opening should be continued to evaluate the need for a mid- summer opening (as was recommended by the MEP for the Sesachacha Pond system) in this system and to improve the present protocol and to set metrics for evaluating a “successful” opening in real time. Summer openings are hindered by restrictions due to piping plover nesting, so it will be important to address this issue as possible over the coming year. As previously stressed, monitoring openings should include wind and tidal conditions during a given opening, pond water level before during and after the opening, water quality before opening and after closure, size of opening {depth and width} and number of days that tidal flows (in and out) occurred. It should be noted that timing and construction of a proper pond opening is a difficult task to accomplish successfully, especially through a large barrier beach like that separating Sesachacha Pond from the ocean waters. The concept is to first document what has worked and what has not to help make the efforts by the Town more beneficial. Future openings in 2018 should 56 continue to be monitored, as for Hummock Pond, to build a database of the details of an effective opening in both Sesachacha Pond (and Hummock Pond). The Ponds Opening Protocol should continue to be refined, with the goal of making future openings more beneficial to the associated pond’s water quality and producing simplified approaches to reduce the effort required for a successful opening. If it is determined that effective openings can not be achieved for either closed pond but in particular Sesachacha Pond, due to the dynamic nature of the barrier beaches being breached, then the town will have to focus on reducing load to the ponds from the watershed or consider in situ approaches for improving water quality. Oyster aquaculture as appropriate is being investigated by towns on Cape Cod. Acknowledgements This work is in collaboration with the Town of Nantucket through its Natural Resources Department and the Marine Department. Special thanks go to Kaitlyn Shaw, Town of Nantucket Water Resources Specialist and the Monitoring Program Coordinator, Assistant Biologist Leah Cabral and to Jeff Carlson, Director - Natural Resources Department, for the extra efforts that they have provided to ensure sampling success and the maintenance of a high quality monitoring program. In addition, the Nantucket Land Council (Cormac Collier) provided support for assessment of Hummock Pond openings and the development of the new opening protocol, with additional support from Land Council staff. It is through the dedication of these groups and the efforts of other environmental stewards in the Town of Nantucket that Nantucket’s estuaries are being protected and in some cases already moving toward restoration. 57 Table 3a. Summary of Water Quality Parameters, 2017 Nantucket Sampling Program. Values are Station Averages of all sampling events, June-September for sampling sites. Station NAN2A represent an MEP sentinel location for monitoring in Nantucket Harbor. NAN-2A is in a new station that was first sampled in 2016 and is in a different location than NAN-2. It should be noted that in 2017, TP was only evaluated in the stream sites, Sesachacha Pond (pre and post opening, Hummock Pond (pre and post opening) and Miacomet Pond because of the expected low salinity values in those closed ponds and the possibility that the Miacomet system maybe phosphorous limited rather than nitrogen limited. Further study should investigate the possibility of P-limitation and TP paired with salinity should continue to be monitored during the summer 2018 field season. 20% Low 20% Low (2017)Secchi Secchi Field Field Avg.Avg.Avg.Avg.Avg.Avg.Avg.Avg.Avg.Avg.Avg.Avg.Chla/T-Pig Avg. average Depth DO DO Salinity PO4 NH4 Nox DIN DON TDN POC PON TON TN Chla Phaeo Ratio Total Pig Embayment Sample ID (meters)% of WC Sat Sat (ppt)(mg/L)(mg/L)(mg/L)(mg/L)(mg/L)(mg/L)(mg/L)(mg/L)(mg/L)(mg/L)(ug/L)(ug/L)(ug/L) (mg/L)(% sat) HUMMOCK POND HUM7 1.81 48%4.67 51%2.11 0.134 0.095 0.004 0.098 0.392 0.490 1.551 0.254 0.646 0.789 11.470 2.438 0.825 13.908 HUMMOCK POND HUM8 0.53 38%6.86 75%2.68 0.123 0.017 0.014 0.031 0.647 0.678 2.788 0.512 1.159 1.200 33.279 11.694 0.740 44.974 HUMMOCK POND HUM5 0.66 32%6.99 77%3.39 0.131 0.039 0.005 0.044 0.577 0.621 2.134 0.382 0.959 1.024 23.904 4.068 0.855 27.972 HUMMOCK POND HUM3 0.83 42%8.36 92%4.10 0.091 0.014 0.004 0.018 0.540 0.558 2.069 0.414 0.954 0.980 22.450 5.163 0.813 27.613 HUMMOCK POND HUM1 0.94 38%7.02 78%4.40 0.079 0.090 0.007 0.096 0.598 0.695 1.719 0.317 0.915 1.078 21.228 4.847 0.814 26.075 LONG POND LONG6 0.85 84%6.51 79%14.61 0.016 0.066 0.009 0.076 0.467 0.543 1.130 0.166 0.634 0.712 9.467 1.452 0.867 10.919 LONG POND LONG5 0.71 67%6.54 78%13.28 0.030 0.005 0.006 0.010 0.480 0.491 2.135 0.375 0.855 0.867 23.565 2.628 0.900 26.192 MADAKET HARBOR MH1 1.47 72%4.91 64%25.78 0.016 0.018 0.011 0.030 0.361 0.391 0.838 0.165 0.527 0.570 9.937 1.833 0.844 11.769 MADAKET HARBOR MH2 1.68 100%6.24 83%29.96 0.014 0.015 0.003 0.018 0.279 0.297 0.452 0.080 0.359 0.386 5.666 1.210 0.824 6.877 MADAKET HARBOR MH3 2.20 94%6.05 77%30.83 0.013 0.021 0.002 0.022 0.236 0.258 0.409 0.069 0.304 0.341 1.600 0.976 0.621 2.576 MADAKET HARBOR MH4 2.83 58%6.15 80%30.90 0.016 0.021 0.001 0.022 0.193 0.215 0.414 0.073 0.266 0.306 3.189 0.842 0.791 4.030 MIACOMET POND MP3 1.35 84%5.25 59%0.10 0.050 0.044 0.027 0.071 0.414 0.485 2.496 0.386 0.800 0.909 11.287 7.352 0.606 18.638 MIACOMET POND MP1 1.63 87%2.86 33%0.24 0.004 0.004 0.002 0.006 0.461 0.467 1.140 0.170 0.633 0.641 10.636 3.784 0.738 14.420 MIACOMET POND MP2 2.23 74%3.08 32%0.33 0.003 0.003 0.002 0.005 0.439 0.445 0.990 0.138 0.577 0.584 7.273 2.002 0.784 9.275 NANTUCKET HARBOR NAN1 3.34 77%5.77 77%30.69 0.014 0.009 0.004 0.013 0.251 0.264 0.283 0.050 0.301 0.317 2.327 0.411 0.850 2.739 NANTUCKET HARBOR NAN2 3.04 63%5.69 77%30.68 0.016 0.014 0.003 0.017 0.227 0.243 0.309 0.054 0.280 0.302 2.406 0.742 0.764 3.148 NANTUCKET HARBOR NAN2A 2.44 43%5.66 77%30.80 0.018 0.030 0.004 0.033 0.249 0.283 0.490 0.086 0.335 0.377 4.412 1.062 0.806 5.474 NANTUCKET HARBOR NAN3 2.30 40%5.93 81%30.84 0.018 0.024 0.003 0.028 0.248 0.276 0.500 0.084 0.332 0.366 5.788 1.014 0.851 6.803 NANTUCKET HARBOR NAN4 2.56 53%6.15 82%30.77 0.014 0.007 0.002 0.010 0.211 0.221 0.353 0.064 0.275 0.288 3.822 0.545 0.875 4.367 NANTUCKET HARBOR NAN5 2.07 82%5.44 74%28.88 0.018 0.021 0.004 0.025 0.283 0.308 0.738 0.112 0.395 0.429 3.828 0.994 0.794 4.821 NANTUCKET HARBOR NAN6 2.18 80%5.60 77%30.34 0.015 0.019 0.003 0.022 0.264 0.286 0.766 0.112 0.376 0.405 5.400 1.112 0.829 6.512 NANTUCKET HARBOR NAN7 1.78 81%5.78 78%30.59 0.016 0.016 0.004 0.019 0.227 0.246 0.463 0.080 0.307 0.333 3.285 0.852 0.794 4.137 NANTUCKET HARBOR NAN8N 1.52 100%5.12 68%30.51 0.015 0.010 0.003 0.013 0.217 0.230 0.348 0.059 0.276 0.293 2.361 0.548 0.812 2.908 Nantucket Hrb. Stream Site ST4 0.18 83%3.11 31%0.08 0.070 0.012 0.006 0.018 0.945 0.963 0.701 0.053 0.998 1.021 1.284 0.544 0.702 1.828 Nantucket Hrb. Stream Site ST4A 0.25 63%1.21 12%0.10 0.039 0.025 0.009 0.034 1.387 1.422 0.457 0.056 1.444 1.478 0.102 0.847 0.107 0.949 Nantucket Hrb. Stream Site ST6 0.20 53%5.75 57%0.02 0.107 0.012 0.006 0.018 0.943 0.961 3.051 0.142 1.084 1.107 3.107 0.857 0.784 3.963 Nantucket Hrb. Stream Site WPH OUTLET 0.13 82%6.90 66%0.25 0.074 0.017 0.008 0.025 0.954 0.979 0.747 0.052 1.006 1.037 0.713 0.616 0.536 1.329 SESACHACHA POND SESA3 0.81 28%7.21 86%11.33 0.236 0.004 0.003 0.006 0.502 0.508 2.459 0.309 0.811 0.819 8.173 1.486 0.846 9.659 SESACHACHA POND SESA2 0.93 21%4.55 52%11.30 0.259 0.004 0.002 0.006 0.526 0.532 2.831 0.358 0.884 0.891 8.724 1.528 0.851 10.252 SESACHACHA POND SESA4 0.93 28%8.28 94%11.33 0.242 0.004 0.002 0.007 0.545 0.552 2.551 0.312 0.857 0.865 7.959 1.285 0.861 9.244 SESACHACHA POND SESA1 1.02 24%5.42 61%11.34 0.268 0.004 0.002 0.006 0.594 0.600 2.753 0.357 0.951 0.960 11.271 2.066 0.845 13.337 OLD NORTH WHARF - Oyster ORS2 1.21 100%5.14 69%30.33 0.016 0.031 0.005 0.036 0.233 0.268 0.294 0.048 0.289 0.329 2.477 0.529 0.824 3.006 SHIMMO Oyster ORS4 1.16 100%3.39 46%29.80 0.019 0.030 0.010 0.039 0.307 0.347 0.315 0.053 0.361 0.414 1.362 0.947 0.590 2.309 POLPIS Oyster ORS6B 0.93 100%3.70 49%29.75 0.019 0.038 0.005 0.043 0.323 0.366 0.431 0.074 0.397 0.460 1.804 0.960 0.653 2.764 58 Table 3b. 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 59 Table 3c. 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 60 Table 3d. 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 61 Table 3e. 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 62 Table 3f. 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 63 Table 3g. 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 64 Figure 15. Comparison of nitrogen species (mg/L) in Nantucket Harbor in summers, 2010-2014 avg. (upper left, not including 2011); 2015 (upper right); 2016 (bottom left); 2017 (bottom right). Total nitrogen is the sum of the inorganic and organic fractions (top line in each graph). All figures are to same scale. 65 Figure 15 cont'd. Comparison of nitrogen species (mg/L) in Hummock Pond in summers, 2010-2014 avg. (upper left, not including 2011); 2015 (upper right); 2016 (bottom left); 2017 (bottom right). Total nitrogen is the sum of the inorganic and organic fractions (top line in each graph). All figures are to same scale. 66 Figure 15 cont'd. Comparison of nitrogen species (mg/L) in Sesachacha Pond in summers, 2010-2014 avg. (upper left, not including 2011); 2015 (upper right); 2016 (bottom left); 2017 (bottom right). Total nitrogen is the sum of the inorganic and organic fractions (top line in each graph). 67 Figure 15 cont'd. Comparison of nitrogen species (mg/L) in Madaket Harbor in summers, 2010-2014 avg. (upper left, not including 2011); 2015 (upper right); 2016 (bottom left); 2017 (bottom right). Total nitrogen is the sum of the inorganic and organic fractions (top line in each graph). All figures are to same scale. 68 Figure 15 cont'd. Comparison of nitrogen species (mg/L) in Long Pond (Madaket Harbor System) in summers, 2010-2014 avg. (upper left, not including 2011); 2015 (upper right); 2016 (bottom left); 2017 (bottom right). Total nitrogen is the sum of the inorganic and organic fractions (top line in each graph). All figures are to same scale. 69 Figure 15 cont'd. Comparison of nitrogen species (mg/L) in Miacomet in summers, 2010-2014 avg. (upper left, not including 2011); 2015 (upper right); 2016 (bottom left); 2017 (bottom right). Total nitrogen is the sum of the inorganic and organic fractions (top line in each graph). All figures are to same scale. 70 Figure 16a. Summer 2017 TN concentrations compared to 2015, 2016 and average of 2010-2014 not including 2011. Figure 16b. Summer 2017 TN concentrations compared to summer 2016 results for both mid harbor station NAN2 and sentinel station NAN2A. Sampling at NAN2A was initiated in summer 2016. 71 Figure 16 cont'd. Summer 2017 TN concentrations compared to 2015, 2016 and average of 2010-2014 not including 2011. Figure 16 cont'd. Summer 2017 TN concentrations compared to 2015, 2016 and average of 2010-2014 not including 2011. 72 Figure 16 cont'd. Summer 2017 TN concentrations in Madaket Harbor compared to 2015, 2016 and average of 2010-2014 not including 2011. Figure 16 cont'd. Summer 2017 TN concentrations compared to 2015, 2016 and average of 2010-2014 not including 2011. 73 Figure 16 cont'd. Summer 2017 TN concentrations compared to 2015, 2016 and average of 2010-2014 not including 2011. 74 Figure 17. Estuarine water quality monitoring station locations in the Nantucket Harbor estuary system. Station labels correspond to those provided in Table 3 below. Red diamonds indicate locations of MEP monitoring stations. Blue diamonds are locations of Town sampling. Station 8 sampled in 2010, station 8N sampled in 2011, 2012, 2013, 2014, 2015, 2016, 2017. 75 Table 4. Comparison of MEP mean TN with Town data (values mg/L) from Nantucket Harbor. MEP data collected in the summers of 1988 - 1990 and 1992 - 1994 by the Woods Hole Oceanographic Institution, and between 1992 and 2005 by the Town of Nantucket Marine Department and by the Nantucket Marine and Coastal Resources Department in summers 2010, 2012, 2013, 2014, 2015, 2017 and 2017. 5 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) 2017 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 0.366 Head of the Harbor - Lwr 2A 0.339 0.070 NA NS NS NS NS NS NS 0.415 NS 0.377 Pocomo Head 3 0.335 0.081 NA NS NS NS NS NS NS NS Quaise Basin 3A+Town 2 0.336 0.112 2 0.297 0.364 0.345 0.314 0.374 0.314 0.302 East Polpis Harbor 4+Town 6 0.362 0.105 6 0.438 0.484 0.401 0.378 0.404 0.371 0.405 West Polpis Harbor 4A+Town 5 0.388 0.119 5 0.431 0.419 0.385 0.389 0.422 0.420 0.429 Abrams Point 5 0.335 0.060 NA NS NS NS NS NS NS NS Monomoy 6 0.297 0.086 NA NS NS NS NS NS NS NS Mooring Area 7+Town 1, 1A 0.326 0.106 1, 7 0.332, 0.377 0.335, 0.379 0.323, 0.323 0.294, 0.284 0.39, 0.33 0.304, 0.319 0.317 Nantucket Sound OS+Town 4 0.239 0.041 4 0.283 0.3445 0.3171 0.277 0.297 0.283 0.288 76 Figure 18. 2005 aerial photo showing MEP monitoring station location in Sesachacha Pond that was used in the water quality analysis for the Massachusetts Estuaries Project. Station SES corresponds to SESA-1 in Tables 2a,b and Station 1 in Figure 3. 77 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) 2017 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) 0.960 (0.884) Table 5. Comparison of MEP mean values of TN with Town TN data (all values are mg/L) from Sesachacha Pond. MEP data were collected in the summers of 1992 through 2005. Town data were collected in the summers of 2010, 2012, 2013 and 2014 by the Town of Nantucket Marine and Coastal Resources Department. Values in 2010, 2012, 2013, 2014, 2015, 2016 and 2017 represent the average at Station 1, with the average of stations 1-4 in ( ). 78 Figure 19. Estuarine water quality monitoring station locations in the Madaket Harbor and Long Pond Systems. 79 Table 6. Comparison of MEP mean values of TN with Town TN data (all values are mg/L) from Madaket Harbor and Long Pond. MEP data were collected by SMAST in the summers of 2002 through 2004. Town data were collected in the summers of 2010, 2012, 2013, 2014, 2015, 2016 and 2017 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) 2017 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 0.306 Madaket Harbor MEP M2 0.395 0.083 Madaket Harbor Town 2 0.436 0.444 0.323 0.347 0.418 0.338 0.386 Madaket Harbor MEP M3 0.415 0.090 Madaket Harbor Town 3 0.324 .356 0.314 0.376 0.324 0.260 0.341 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 0.570 Long Pond MEP LOPO1 1.058 0.404 Long Pond MEP LOPO2+Town 5 0.971 0.369 1.385 1.013 0.709 1.481 0.697 0.649 0.867 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 0.712 North Head Long P. MEP LOPO5 0.954 0.271 80 Hummock Pond and Miacomet Pond Station ID's 2017 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) TN (mg/L) Mean Mean Mean Mean Mean Mean Mean Mean S.D. HUM1 1.078 0.594 0.539 0.651 0.769 0.666 0.616 0.751** 0.374 HUM3 0.980 0.654 0.622 0.643 0.827 0.863 0.589 0.630** 0.388 HUM5 1.024 0.868 0.558 0.653 0.881 0.871 0.766 ND ND HUM7 0.789 0.673 0.621 0.873 1.170 1.301 1.786 1.283** 0.969 HUM8 1.200 1.194 0.576 0.755 1.064 0.944 0.983 ND ND MP1 0.641 0.772 1.297 0.864 0.792 0.828 0.854 0.842* 0.191 MP2 0.584 0.669 1.318 0.784 1.036 0.880 0.811 0.855* 0.213 MP3 0.909 0.783 0.992 1.297 1.058 0.950 1.093 0.280* 0 *2005 data only **2007 data only Table 7. Comparison of TN concentrations collected in 2005 (Miacomet Pond) and 2007 (Hummock Pond) by Nantucket Marine and Coastal Resources Department with Town TN data collected at both sites the summer of 2010, 2012, 2013, 2014, 2015, 2016 and 2017. All values are mg/L. 81 2017 Low20%2017 EMBAYMENT Secchi Oxsat DIN TON T-Pig EUTRO Health Status SCORE SCORE SCORE SCORE SCORE Index HUM1 27.7 83.1 16.3 0.0 0.0 25.4 Fair-Poor HUM3 19.8 100.0 89.1 0.0 0.0 41.8 Moderate HUM5 5.6 80.3 50.3 0.0 0.0 27.2 Fair-Poor HUM7 68.7 30.3 15.4 0.0 0.0 22.9 Fair-Poor HUM8 0.0 78.1 65.5 0.0 0.0 28.7 Fair-Poor LONG5 10.7 81.9 100.0 0.0 0.0 38.5 Moderate-Fair LONG6 21.6 83.9 26.8 0.0 0.0 26.5 Fair-Poor MH1 55.5 57.9 67.6 17.1 0.0 39.6 Moderate-Fair MH2 63.8 89.5 88.2 67.5 31.1 68.0 High-Moderate MH3 80.7 81.0 79.5 89.1 100.0 86.1 High MH4 96.4 85.1 79.4 100.0 75.5 87.3 High MP1 61.9 0.0 100.0 0.0 0.0 32.4 Moderate-Fair MP2 81.4 0.0 100.0 5.2 6.2 38.6 Moderate-Fair MP3 50.4 48.4 29.6 0.0 0.0 25.7 Fair-Poor NAN1 100.0 80.6 100.0 90.6 100.0 94.2 High NAN2 100.0 80.6 92.0 99.8 96.0 93.7 High NAN2A 87.2 81.4 62.3 76.5 50.1 71.5 High NAN3 83.6 87.0 70.7 77.6 32.0 70.2 High NAN4 90.2 87.8 100.0 100.0 68.8 89.4 High NAN5 76.9 76.3 75.6 54.9 60.6 68.8 High NAN6 80.1 80.3 80.3 61.5 35.6 67.6 High-Moderate NAN7 67.7 81.7 86.0 87.9 73.3 79.3 High NAN8N 57.7 66.3 100.0 100.0 100.0 84.8 High SESA1 32.9 51.7 100.0 0.0 0.0 36.9 Moderate-Fair SESA2 26.9 33.3 100.0 0.0 0.0 32.0 Moderate-Fair SESA3 18.4 94.0 100.0 0.0 2.9 43.1 Moderate SESA4 27.0 100.0 100.0 0.0 6.5 46.7 Moderate Table 8a. 2017 Trophic Health Index Scores and status for water quality monitoring stations in Nantucket estuaries based upon open water embayment (not salt marsh) habitat quality scales. Index calculated with Dissolved Oxygen data (described in Howes et. al., 1999 at www.savebuzzardsbay.org). 82 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 8b. 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). 83 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 8c. 2015 Trophic Health Index Scores and status for water quality monitoring stations in Nantucket estuaries based upon open water embayment (not salt marsh) habitat quality scales. Index calculated with Dissolved Oxygen data (described in Howes et. al., 1999 at www.savebuzzardsbay.org). 84 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 8d. 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). 85 Table 8e. 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 86 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 8f. 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). 87 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 8g. 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). 88 2017 Low20%2017 EMBAYMENT Secchi Oxsat DIN TON T-Pig EUTRO Health Status SCORE SCORE SCORE SCORE SCORE Index HUM1 27.7 83.1 16.3 0.0 0.0 11.0 Fair-Poor HUM3 19.8 100.0 89.1 0.0 0.0 27.2 Fair-Poor HUM5 5.6 80.3 50.3 0.0 0.0 14.0 Fair-Poor HUM7 68.7 30.3 15.4 0.0 0.0 21.0 Fair-Poor HUM8 0.0 78.1 65.5 0.0 0.0 16.4 Fair-Poor LONG5 10.7 81.9 100.0 0.0 0.0 27.7 Fair-Poor LONG6 21.6 83.9 26.8 0.0 0.0 12.1 Fair-Poor MH1 55.5 57.9 67.6 17.1 0.0 35.1 Moderate-Fair MH2 63.8 89.5 88.2 67.5 31.1 62.7 High-Moderate MH3 80.7 81.0 79.5 89.1 100.0 87.3 High MH4 96.4 85.1 79.4 100.0 75.5 87.8 High MP1 61.9 0.0 100.0 0.0 0.0 40.5 Moderate MP2 81.4 0.0 100.0 5.2 6.2 48.2 Moderate MP3 50.4 48.4 29.6 0.0 0.0 20.0 Fair-Poor NAN1 100.0 80.6 100.0 90.6 100.0 97.7 High NAN2 100.0 80.6 92.0 99.8 96.0 96.9 High NAN2A 87.2 81.4 62.3 76.5 50.1 69.0 High NAN3 83.6 87.0 70.7 77.6 32.0 66.0 High-Moderate NAN4 90.2 87.8 100.0 100.0 68.8 89.8 High NAN5 76.9 76.3 75.6 54.9 60.6 67.0 High-Moderate NAN6 80.1 80.3 80.3 61.5 35.6 64.4 High-Moderate NAN7 67.7 81.7 86.0 87.9 73.3 78.7 High NAN8N 57.7 66.3 100.0 100.0 100.0 89.4 High SESA1 32.9 51.7 100.0 0.0 0.0 33.2 Moderate-Fair SESA2 26.9 33.3 100.0 0.0 0.0 31.7 Moderate-Fair SESA3 18.4 94.0 100.0 0.0 2.9 30.3 Moderate-Fair SESA4 27.0 100.0 100.0 0.0 6.5 33.4 Moderate Table 9a. 2017 Trophic Health Index Scores and status for water quality monitoring stations in Nantucket estuaries based upon open water embayment (not salt marsh) habitat quality scales. Index calculated without Dissolved Oxygen data (described in Howes et. al., 1999 at www.savebuzzardsbay.org). 89 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 9b. 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). 90 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 9c. 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). 91 Table 9d. 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 92 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 9e. 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). 93 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 9f. 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). 94 Figure 20. Madaket Harbor Eutrophication Index 2010 (top triangle) and 2017 (bottom triangle). Index was calculated with dissolved oxygen. Colors indicate High (Blue), Moderate (Yellow), Fair/Poor (Red) nutrient related water quality. 95 Figure 21. Nantucket Harbor Eutrophication Index 2010 (top triangle) and 2017 (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. 96 Figure 22. Sesachacha Pond Eutrophication Index 2010 (top triangle) and 2017 (bottom triangle). Index was calculated with dissolved oxygen. Colors indicate High (Blue), Moderate (Yellow), Fair/Poor (Red) nutrient related water quality. 97 Figure 23. Hummock Pond Eutrophication Index 2010 (top triangle) and 2017 (bottom triangle). Index was calculated with dissolved oxygen. Colors indicate High (Blue), Moderate (Yellow), Fair/Poor (Red) nutrient related water quality. 98 Figure 24. Miacomet Pond Eutrophication Index 2010 (top triangle) and 2017 (bottom triangle). Index was calculated with dissolved oxygen. Colors indicate High (Blue), Moderate (Yellow), Fair/Poor (Red) nutrient related water quality.