Loading...
Nantucket_WQ_Tech_Memo_2015_FINAL 1 Technical Memorandum FINAL Water Quality Monitoring and Assessment of the Nantucket Island-Wide Estuaries and Salt Ponds Update 2015 To: Town of Nantucket Marine and Natural Resources Department 2 Bathing Beach Road Nantucket, MA 02554 Rosemary Blacquier Woodard & Curran From: Brian Howes Ph.D. and Roland Samimy Ph.D. Coastal Systems Program School of Marine Science and Technology (SMAST) University of Massachusetts-Dartmouth 706 South Rodney French Blvd. New Bedford, MA 02744 January 7, 2016 2 The Technical Memorandum on the 2015 Nantucket Water Quality Monitoring Program is organized consistent with previous SMAST water quality monitoring summaries (2010, 2012, 2013, and 2014) for direct comparison to data from the previous years of monitoring. However, the 2015 summary does not include an overview of the program or the summary of the sampling approach as neither of those two sections have changed from previous years and it is included by reference.. The 2015 summary is focused specifically on the following: 1. Results of Sampling: Summary of Water Quality Results Nantucket Harbor Madaket Harbor Long Pond Hummock Pond Miacomet Pond Sesachacha Pond Polpis Harbor Streams Oyster Aquaculture Sites 2. Trophic State: Water Quality/Eutrophication Status 3. Recommendations for Future Monitoring As in previous years, the 2015 water quality monitoring of Nantucket's fresh and saltwater systems was focused on summer-time conditions, as the warmer months typically have the lowest water quality conditions, which are the target of resource management. As in previous years (2010, 2012-2014), the approach utilized for the collection and analysis of 2015 water samples from each of the estuaries of Nantucket remains the same. This consistency is intended to maximize the value of the results by making the data perfectly cross comparable to water quality monitoring data collected across the Island of Nantucket from previous years and more broadly throughout the region (Cape Cod, Martha's Vineyard). In this manner, inter-ecosystem comparisons can be made to better assess system health/impairment and function and formulate appropriate nutrient management strategies. This allows individual towns such as Nantucket to directly benefit from lessons learned throughout the wider region. As in past years, UMD-SMAST Coastal Systems Program (CSP) scientists focused primarily on the analysis of samples collected from the field effort and data analysis and program coordination with the Nantucket Natural Resources Department who’s primary focus was on coordination of field efforts, field sampling and data collection on physical parameters and water quality improvement efforts. The goals of the monitoring program remain unchanged from previous years, primarily to: 1. determine the present (2015) ecological health of each of the main salt ponds and estuaries within the Town of Nantucket, 3 2. gauge (as historical data allows) the decline or recovery of various salt ponds and embayments over the long-term (also part of TMDL compliance), and 3. provide the foundation (and context) for detailed quantitative measures to derive and assess potential alternatives for nutrient and resource management, as appropriate. This latter point (3) is critical for restoration planning should a system be found to be impaired or trending toward impairment and is also is required to develop cost-effective targeted solutions. As was the case in 2010, 2012, 2013, and 2014 sampling efforts, 2015 sampling took place during the summer/early fall months (May-September). Samples were collected from 6 estuarine systems (Figures 1, 2, 3, 4 and 5) on multiple dates (“events”) following the schedule presented in Table 1a (2015), Table 1b (2014), Table 1c (2013), Table 1d (2012), and Table 1e (2010). Samples collected in 2015 were obtained from the same sampling station locations and the same depths as in previous years to maximize cross comparability and to gauge temporal changes. It should be noted that the Town of Nantucket did undertake water quality monitoring in 2011, however, those samples were analyzed by a lab other than the Coastal Systems Analytical Facility at the UMASS School for Marine Science and Technology. The 2011 water quality data is presented in tabular form in Appendix A in Annual Technical Memoranda (2012, 2013) and are not being reproduced again herein. The physical parameters measured in the estuaries during the 2015 sampling season included: total depth, Secchi depth (light penetration), temperature, conductivity/salinity (YSI meter), general weather (rain, cloudiness, etc), wind force and direction, dissolved oxygen levels and observations of moorings, birds, shell fishing and unusual events (fish kills, algal blooms, etc). Laboratory analyses of estuarine waters included: salinity, nitrate + nitrite, ammonium, dissolved organic nitrogen, particulate organic carbon and nitrogen, chlorophyll-a and pheophytin-a and orthophosphate. Similar to the summer of 2014, the water quality monitoring undertaken in 2015 was focused mostly on estuarine stations with an additional 3 stream locations. In 2015, 32 field duplicates were taken as part of the field sampling protocol for QA analysis. Data were compiled and reviewed by the laboratory for accuracy and evaluated to discern any possible artifacts caused by improper sampling technique, physical disturbance, etc. In addition, some samples were rerun to confirm prior results. The Town of Nantucket has been working for decades to protect and more recently restore its estuaries and their aquatic resources. At present, activities to lower nitrogen enrichment and its negative impacts to water quality are underway associated with Nantucket Harbor (jetties and sewers), Long Pond (landfill), Sesachacha Pond (openings), Hummock Pond (refined opening protocol). All estuaries should also benefit from the recent fertilizer application by-law. As a result, it is anticipated that the monitoring data will begin reflecting these activities. As noted below, summer 2015 appears to have sustained high water quality for most Nantucket Harbor stations though some did show a possible slight decrease in water quality. Hummock Pond water quality in the summer of 2015 showed improvement, most likely due to newly implemented opening protocol resulting in significantly more effective openings and continuing trend 4 toward improved conditions in Long Pond and decline in Miacomet Pond seen in the chlorophyll a pigments, nitrogen and eutrophication index (see below). This analysis revealed that the significant improvement in Sesachacha Pond seen previously has diminished and the Pond has declined in nitrogen related water quality over the past 2 years (2014, 2015) possibly due to the inlet openings. If so, this recent decline should be readily reversible. Table 1a. Sampling Schedule for 2015 Nantucket Water Quality Monitoring Program Month Nantucket Harbor Madaket Harbor Long Pond Sesachacha Pond Miacomet Pond Hummock Pond Polpis Streams Oyster Sites Jan Feb Mar April May May 7 May 12 May 11 May 11 May 12, 27 June June 9, 22 June 8 June 17 June 15 June 15 June 17 June 8 June 9 July July 8, 20 July 6 July 13 July 15 July 15 July 13 July 6 July 6 August Aug 4,19 Aug 5 Aug 17 Aug 10 Aug 10 Aug 12 Aug 3, 31 Aug 3 September Sept 1 Sept 3 Sept 14 Sept 10 Sept 10 Sept 9 Sept 2 October November December Total Events 8 4 5 5 5 6 4 4 5 Table 1b. Sampling Schedule for 2014 Nantucket Water Quality Monitoring Program Note: * The September 15 sampling of Nantucket Harbor only involved one station (NAN-4). Table 1c. Sampling Schedule for 2013 Nantucket Water Quality Monitoring Program Month Nantucket Harbor Madaket Harbor Long Pond Sesachacha Pond Miacomet Pond Hummock Pond Jan Feb Mar April May May 6 May 14 May 20 May 14 May 7, 19 June June 4, 17 June 19 June 11 June 12 June11 June 10 July July 1, 17 July 2 July 23 July 30 July 30 July 23 August Aug 4, 14 Aug 18 Aug 21 Aug 19 Aug 19 Aug 21 September Sept 2, 15* Sept 15 Sept 4 Sept 4 Sept 18 Sept 18 October November December Total Events 8 4 5 5 5 6 Month Nantucket Harbor Madaket Harbor Long Pond Sesachacha Pond Miacomet Pond Hummock Pond Jan Feb Mar April May May 28 May 22 May 22 May 21 June June 13, 25 June 12 June 4,26 June 5 June 5 June 6 July July 17, 30 July 16 July 10 July 9 July 9 July 2 August Aug 13, 28 Aug 12 Aug 21 Aug 21 Aug 6 Aug 14 September Sept 9 Sept 10 Sept 24 Sept 19 Sept 24 Sept 18 October November December Total Events 7 5 5 5 5 5 6 Table 1d. Sampling Schedule for 2012 Nantucket Water Quality Monitoring Program Table 1e. Sampling Schedule for 2010 Nantucket Water Quality Monitoring Program Month Nantucket Harbor Madaket Harbor Long Pond Sesachacha Pond Miacomet Pond Hummock Pond Jan Feb Mar April May May 29 June June 7, 28 June 12 June 25 June 20 June 20 June 27 July July 9, 26 July 11 July 24 July 19 July 19 July 31 August Aug 7, 22 Aug 8 Aug 21 Aug 23 Aug 23 Aug 24 September Sept 6 Sept 7 Sept 25 Sept 25 Sept 27 Sept 26 October November December Total Events 8 4 4 4 4 4 Month Nantucket Harbor Madaket Harbor Long Pond Sesachacha Pond Miacomet Pond Hummock Pond Streams Jan Feb Mar April May May 18 May 20 May 19 May 26 May 26 May 25 June June 2, 17 June 3, 15 June 17 June 24 June 24 June 29 June 28 July July 1, 15, 30 July 16, 27 July 29 July 26 July 26 July 28 August Aug. 13 Aug. 12, 30 Aug. 11 Aug. 26 Aug. 26 Aug. 27 September Sept. 1, 14 Sept. 13 Sept. 15 Sept. 23 Sept. 23 Sept. 28 October Oct. 21 November December Totals 10 8 5 5 5 5 1 7 Figure 1. Madaket Harbor and Long Pond sampling stations 2010, 2012, 2013, 2014, and 2015. 8 Figure 2. Nantucket Harbor sampling stations 2015. Station NAN-8 (the cut) was only sampled in 2010 and location changed in 2011 - 2015. Nantucket Harbor and Polpis Harbor each have nitrogen thresholds in the MassDEP/USEPA TMDL for this system. 9 Figure 3. Sesachacha Pond sampling stations 2010, 2012, 2013, 2014, 2015. 10 Figure 4. Hummock Pond sampling stations 2010, 2012, 2013, 2014, 2015. Station 7 is in Head of Hummock, a kettle pond connected by an artificial channel to the estuary and a configuration that maintains a salinity gradient from Station 7 to Station 8. 11 Figure 5. Miacomet Pond sampling stations 2010, 2012, 2013, 2014, and 2015. Station 3 Station 1 Station 2 Station 3 Station 1 Station 2 12 Figure 6. Polpis Harbor Stream Sampling locations (ST-3,4,6B) 2015. Water samples from mid depth in water exiting culverts. 13 Figure 7a. Oyster Aquaculture Sampling locations Nantucket Harbor (ORS-2,3,4,5,6) and Madaket Harbor (ORS-1) 2015. Sites are associated with possible oyster aquaculture areas. Figure 7b. Oyster Aquaculture Sampling location Madaket Harbor (ORS-1) 2015. Site is associated with possible oyster aquaculture areas. 14 Summary of 2015 Water Quality Results for Nantucket Sampling While there were some localized areas of interest (Hummock Pond {+}, Miacomet Pond {-}, Long Pond {+}1, see below), the overall trends in water quality observed in 2015 follow and expand the pattern observed in 2010, 2012, 2013, 2014. Water samples collected from May through September in the estuarine systems indicate that organic nitrogen (dissolved + particulate) still dominates the Total Nitrogen pool (96% in 2015 alone), while bio-available nutrients in the form of nitrite and nitrate (NOx) and ammonium (NH4) account for only 4% of Total Nitrogen pool in 2015 (Table 2a,b,c,d,e Figure 14). The observed distribution of the nitrogen fractions comprising total nitrogen are typical for estuarine systems throughout New England, where nitrogen is the nutrient responsible for eutrophication and therefore the nutrient critical for management. The predominance of organic nitrogen in the Total Nitrogen (TN) pool in these systems would indicate that they are effectively converting the bioavailable inorganic forms of nitrogen into organic forms (e.g. phytoplankton). Where tidal flushing is effective, much of this particulate matter along with dissolved nutrients is washed out of the system resulting in good water clarity as evidenced by the greater Secchi depth readings in the main basins of Nantucket Harbor and Madaket Harbor in 2015 (Table 2a), as noted in prior years as well (Table 2b,c,d,e). Consistent with the water clarity, corresponding chlorophyll-a pigment concentrations were lowest (2-4 ug/L) in these well flushed systems (Table 2a,b,c,d,e, Figure 8,9). The level of variation is common and underscores the need for multi-year monitoring to establish trends. Figure 8. Average Chlorophyll-a (CHLA) concentrations by station in the well flushed Nantucket Harbor system during the summer 2015 sampling season. Stations Nan-5 1 {+} indicates improved conditions in 2015; {-} indicates declining conditions in 2015. 15 and 6 are in Polpis Harbor the rest relate to the main basin. Note that 2015 levels were about average within the upper basins and relatively constant throughout the Harbor at a level consistent with low-moderate nitrogen enrichment. Figure 9. Average Chlorophyll-a (CHLA) concentrations by station in the well flushed Madaket Harbor system during the summer 2015 sampling season. Stations MH-2,3,4 are in the main open basin, MH-1 is the MEP sentinel station in Hither Creek. The 2010 blooms have not been as prevalent in recent years but 2015 total pigment levels were slightly higher than in 2014, similar to the lower reaches of Nantucket Harbor. While Nantucket Harbor and Madaket Harbor are both well flushed basins, they tended to have slightly higher phytoplankton biomass (chlorophyll-a) in 2015 compared to 2014. This was most striking in Nantucket Harbor where average chlorophyll-a at station 3 was high compared to prior years. In Madaket Harbor the levels were also higher than all years but 2010. This is consistent with the lower water clarity observed in 2015 (Nantucket Harbor station 3 secchi depth 2014 = 3.1 m, 2015 = 1.45 m, Madaket Harbor MH-2 secchi 2.5 meters in 2014, 2.2 in 2015) as turbidity is primarily the result of organic particulates, e.g. phytoplankton. The parallel measurements of total nitrogen (TN) are generally consistent with the chlorophyll-a results, showing higher TN levels with higher chlorophyll-a levels (see below). This is particularly apparent in Nantucket Harbor (station 3) and provides additional evidence that nitrogen is the eutrophying nutrient in these systems. Where tidal flushing is more restricted in Long, Hummock, Miacomet and Sesachacha Ponds, the moderate levels of water clarity were consistent with the chlorophyll-a concentrations that have a higher (2x-3x) average (compared to Nantucket and Madaket Harbors), 5.7 ug/L (max. 11.37 ug/L), 4.6 ug/L (max. 16.6 ug/L), 37.96 ug/L (max. 158.6 ug/L) and 6.74 ug/L (max. 10.74 ug/L), respectively (Table 2a, Figures 10, 11,12,13). These general patterns were also observed in the monitoring results of the prior year (2014, 2.6 ug/L, 4.4 ug/L, 4.2 ug/L and 3.0 ug/L). However, it should be noted that the 16 chlorophyll-a levels in Long Pond, Hummock Pond, Miacomet Pond and Sesachacha Pond all appear to be higher when compared to 2014 average values. In Sesachacha Pond chlorophyll-a levels have risen slightly in 2015 compared to 2014 (maybe due to a less effective opening compared to the prior years of 2012, 2013 and 2014). Additionally, total pigment values (chlorophyll-a + pheophytin) were significantly higher in Miacomet Pond in 2015 compared to 2014 (45.9 ug/L vs. 11.1 ug/L). While generally all the sampling dates for Miacomet Pond showed elevated levels for total pigment in 2015, consistent with other estuaries, one date had exceptionally high values at all stations indicating that sampling likely occurred during a strong bloom event. The multi-year results clearly show that 2010 was a poor water quality year as was also seen in the open basins, e.g. Madaket Harbor. Over the past 4 years, chlorophyll-a levels in Long Pond, Hummock Pond, Miacomet Pond and Sesachacha Pond have dropped compared to historic levels and 2010 but do show variation (e.g. all ponds higher in 2015 compared to 2014). However, Sesachacha Pond showed much improved water quality compared to its long term status during the MEP assessment that indicated chlorophyll-a levels generally >20 ug/L, frequently >60 ug/L and blooms as high as 100 ug/L. It appears that Sesachacha Pond quality is tightly linked to the success of its periodic openings, which significantly improved conditions in 2012 and 2013, but has recently showed declines in 2014 and 2015. This was clearly seen in 2014 as well as 2015 though in 2015 TN levels appeared higher than in 2014 with an associated increase in total pigment levels (potentially related to a less effective opening in 2015 compared to 2014). The temporal data indicate that Sesachacha Pond can be significantly restored by improved pond openings and that recent openings need to be re-examined relative to the recent increase in nitrogen enrichment and associated water quality metrics (chlorophyll, dissolved oxygen). After a significant drop in chlorophyll-a in 2013 (versus 2010, 2012) Long Pond has maintained its phytoplankton levels at a high/moderate level 2013-2015. This decline was noted previously and is possibly a result of activities at the landfill leading to declining nitrogen inputs. However, Long Pond continues to be eutrophic and impaired. In contrast, Miacomet Pond which is not open to tidal flows and has become very fresh (avg. salinity 0.10 ppt), showed a large increase in chlorophyll-a levels in 2015 and showed the highest levels since the monitoring program began and the highest of all Nantucket’s estuaries. Miacomet Pond is clearly supporting eutrophic conditions for both fresh and salt water (>35 ug/L total pigment). Moreover the phytoplankton bloom was pond-wide and persisted throughout the sampling period. Hummock Pond showed significantly lower total chlorophyll-a levels in summer 2015 than prior years (2010,2012,2013) although slightly higher compared to 2014. The 2014 results were the lowest levels measured over the 2010-2015 monitoring period and while 2015 was slightly higher than 2014, chlorophyll levels in 2015 were still moderate- high as a metric of eutrophication. While two years (2014 and 2015) only represent the beginning of a restoration trend, the lower levels in those two years is consistent with an improved opening protocol developed in 2014 for the Hummock Pond openings. The Town and the Nantucket Land Council entered into a project to refine the opening protocol for Hummock Pond to maximize the amount of tidal flushing achieved by the openings. The April 2014 opening of Hummock Pond was moderately successful followed by a more effective opening in October 2014 which lowered TN levels in the pond and raised its salinity. It is possible that the combination of the good opening and the meteorological conditions that appear to have supported higher water quality in most 17 of the estuaries in summer 2014 was the cause of the relatively low total chlorophyll-a and TN in Hummock Pond in 2014. Total chlorophyll-a was the lowest at each monitoring station in 2014 when compared to prior years. In April 2015, Hummock Pond was opened and water levels and water quality were monitored before and after the opening. The April 2015 opening did appear to be a more effective opening compared to the October 2014 opening thereby contributing to the enhanced water quality observed during the summer 2015. Average TN levels in the summer of 2015 were moderately lower than in summer 2014 (0.583 mg/L and 0.715 mg/L respectively) though average total pigment in 2015 was slightly higher than in 2014 (9.68 ug/L and 7.08 ug/L respectively). It is possible that the slightly higher total pigment values observed in 2015 despite slightly lower TN values is the result of the warmer conditions experienced during the summer of 2015. Also, it is clear that the pond has not reached equilibrium with its new hydrodynamic conditions, such that further improvements are anticipated if the new opening protocol is continued. The opening protocol will be further refined as more data is gathered from future openings and the water quality monitoring will allow evaluation of this revised management tool. min max avg System CHLA CHLA CHLA (ug/L)(ug/L)(ug/L) Miacomet Pond 2.80 204.83 41.26 Sesachacha Pond 3.08 11.23 6.79 Long Pond 2.56 11.37 5.44 Hummock Pond 1.00 19.71 4.50 min max avg System Total Pig Total Pig Total Pig (ug/L)(ug/L)(ug/L) Miacomet Pond 9.55 204.86 48.71 Sesachacha Pond 6.56 18.79 11.10 Long Pond 4.40 19.54 9.30 Hummock Pond 2.92 43.41 9.24 Figure 10. Average Chlorophyll-a (CHLA) concentrations by station in the Long Pond portion of the Madaket Harbor system during the summer 2015 sampling season compared to 2010, 2012, 2013, and 2014. 18 Figure 11. Average Chlorophyll-a (CHLA) concentrations by station in the seasonally opened Hummock Pond system during the summer 2015 sampling season compared to 2010, 2012, 2013, and 2014. Figure 12. Average Chlorophyll-a (CHLA) concentrations by station in the Miacomet Pond system during the summer 2014 sampling season compared to 2010, 2012, 2013, and 2014 Miacomet Pond is not opened to the Atlantic Ocean. 19 Figure 13. Average Chlorophyll-a (CHLA) concentrations by station in the seasonally opened Sesachacha Pond system during the summer 2015 sampling season compared to 2010, 2012, 2013, and 2014. Average Total Nitrogen values in Hummock Pond were lower in 2015 even though total pigment appeared slightly higher than in 2014. Total nitrogen averaged 0.583 mg/L in 2015 whereas in prior years [2014, 2013, 2012, 2010] average TN values where [0.715, 0.900, 0.923, 0.944] mg/L respectively. This temporal trend is consistent with the timing of improved flushing observed in 2014 and 2015 openings, as is the decline from 2014 to 2015 which is expected from a system in transition. In contrast, Miacomet Pond which had no restoration activities or openings showed higher TN levels in 2015 compared to the previous 4 years of monitoring: 1.202 mg/L compared to [0.982, 0.962, 0.919, 0.886] mg/L respectively. These high levels of TN are consistent with small estuaries that only receive tidal water through periodic openings (Hummock Pond) or overwash during storm events (Miacomet Pond) and are poorly flushed. The effect of flushing is clearly seen by comparing TN and pigment levels in Nantucket’s well flushed estuaries (Nantucket and Madaket Harbors) to these “closed” poorly flushed estuaries. Total Nitrogen values appear to be temporally variable in both Long Pond 0.656-0.697 [1.14, 0.795, 0.94,1.75] mg/L and in Sesachacha Pond 0.904 [0.922, 0.669, 0.704, 0.639] mg/L. Like Hummock and Miacomet Ponds, Long Pond and Sesachacha Ponds are also poorly flushed. In the case of Sesachacha Pond, the TN levels also appear to be related to the success of the periodic openings. The similar TN levels in 2015 as compared to 2014 likely relate to similar opening characteristics and are higher than the prior 2 years which had better openings. It is worth noting that the high historic levels and 2010 levels were under less robust opening conditions, prior to the Town’s new awareness of the importance openings as a pond management tool. It should be noted that TN levels in 2015 (and 2014) remain significantly lower than during the MEP assessment and suggest that achieving the TMDL may be possible by refined openings, 20 saving infrastructure costs. Average TN levels in all 4 ponds are significantly higher than average values in the “offshore” stations NAN 4 and MH4 which average 0.297 [0.277, 0.317, 0.344, 0.302] and 0.328 [0.254, 0.278, 0.297, 0.285] mg/L, respectively (Tables 2a, 2b, 2c, 2d, 2e, Figures 1, 2). It should be noted that the average offshore TN concentration for station MH4 is 0.295 mg/L if the 8/5/2015 sampling date (TN concentration = 0.427 mg/L) is not included in the calculation. It is possible that sample data for that one sampling date is aberrant, which is supported by statistical analysis of the complete data set (2010-2015). Long Pond showed significantly lower TN levels (~40%) in 2012 versus 2010. Levels at Station 5 declined from 2012 to 2013 and held steady or improved in 2013, however there was an increase in average TN levels from 2013 to 2014 at station 5 (1.48 mg/L in 2014 vs. ~0.70 mg/L in 2013). TN concentrations at station 5 declined again in 2015 to 0.656 mg/L from 1.48 mg/L in 2014. This variation in TN levels at station 5 needs to be tracked closely by the monitoring program, as MEP modeling suggests that conditions will improve as the landfill process continues. Station 6 continued to show a decrease in TN concentrations. Station 6 TN concentrations in 2015 dropped to 0.697 mg/L from 0.788 mg/L in 2014. Based on the lower TN concentrations observed in 2015, it is possible that the increase in TN levels at station 5 from 2013 to 2014 represented a natural inter-annual variation. While it is unusual for one station to increase and not the adjacent station, in this case it may be the result of poor horizontal mixing in Long Pond due to a changes in tidal action through Madaket Ditch. Although it has been observed previously, mixing even if through only dispersion should not allow the large difference in TN levels. Continued monitoring of station 5 is warranted. The long-term lowering of the TN levels, particularly at station 6, appears to follow Town activities at the landfill, as 2015, 2014 and 2013 TN levels follow a downward trend and chlorophyll-a levels in Long Pond are significantly lower than in 2010 and 2012 and generally similar to what was measured in 2013 and 2014. The monitoring program will be assessing potential causes of the large temporal variations in the lower basin of Long Pond (Station 5). As in all previous years, in Sesachacha Pond, there is no noticeable nutrient or chlorophyll gradient among any of the 4 Stations (Figure 13 and 14, Tables 2a,b,c,d,e) because of the closed nature of the pond and the shape of its basin, it's mixing is more like a freshwater lake than an estuary. However, it should be noted that while TN and chlorophyll-a concentrations in Sesachacha Pond where generally higher in 2014 compared to 2013, TN levels in 2015 remained high and very similar to 2014 (0.904 mg/L and 0.922 mg/L respectively). Total pigment in 2015 was higher than what was observed in 2014 (11.07 ug/L and 6.37 ug/L respectively), however, the higher pigment levels in 2015 were generally observed across all the estuaries of Nantucket indicating the higher levels likely meteorologically related. It should be noted that the average temperature May-September 2015 (22.6 degrees Celsius) was highest when compared to 2010-2014 (22.5, 19.8, 22.3, 19.6, 19.3 degrees Celsius respectively). That there was a noticeable increase from 2013 to 2014 and consistency between 2014 and 2015 is good reason to continue regular monitoring of the system, particularly to determine changes in the effectiveness of annual pond openings that are the likely driver for increased or decreased water quality in a given year. However, TN levels are now above the nitrogen threshold in the TMDL, and the 2014 and 2015 increase is a cause for concern, particularly after a few years of much lower TN levels (~0.6 mg/L). 21 Consistent with previous years monitoring results, Madaket Harbor shows a clear nitrogen gradient (and associated metrics) from Station 1 in Hither Creek (which receives discharge from Long Pond via Madaket Ditch), and is relatively poorly flushed, out to Station 2 in the Harbor, with further decreases out to the off-shore Station 4 (Figure 9 and 14, Table 2a). Similarly, in Nantucket Harbor, there is a very small nutrient gradient from Wauwinet at the Head of the Harbor and the more enclosed Polpis stations out to the entrance at Stations 8 and 4. There is also a chlorophyll gradient with the highest concentrations at the 2 Polpis Stations (5 and 6) and Wauwinet basin, decreasing in the main Harbor and out to the off-shore Station 4. Average 2015 [2014, 2013, 2012, 2010] TN level in Madaket Harbor (Stations 1-3, not including Station 4, offshore) was 0.422 [0.390, 0.404, 0.485, 0.462] mg/L, compared to the off-shore Station 4 0.328 [0.254, 0.278, 0.297, 0.285] mg/L. As mentioned above, the best estimate of the offshore TN concentration for station MH4 is 0.295 mg/L. Average TN in Nantucket Harbor (all Stations except Station 4, offshore) were quite low averaging 0.381 mg/L compared to 2010, 2012, 2013, 2014, with the offshore boundary station 4 averaging only 0.297 mg/L in 2015 (Tables 2a, 2b). It should be noted that the 2010 value includes station NAN-8 (the cut) whereas the 2015, 2014, 2013 and 2012 value includes station NAN-8N which was relocated into the Town Basin within the Harbor (refer to Figure 2 for station location). TN concentrations in the 6 streams adjacent to Nantucket Harbor in 2010 ranged from 0.565 mg/L in Stream 8 to 2.139 mg/L in Stream 6B (Table 2e). In spite of the high TN concentrations in these 6 streams and the TN loads that these streams contribute to the Harbor, tidal flushing and dilution with lower concentration Harbor waters seems to be an effective mechanism to keep TN levels in the main body of the Harbor relatively low (Table 2a,b,c,d; Figure 2). A subset of streams sampled in 2010 where sampled again in 2015 and the results are discussed below. It should be noted that the stream stations were not sampled in 2012, 2013 or 2014, however, with increasing interest in lowering TN concentrations in Polpis Harbor, it was warranted to periodically sample streams discharging to this tributary sub- embayment. TN concentrations in East Polpis Harbor, 0.404 [0.378, 0.401, 0.438, 0.484] mg/L and West Polpis Harbor 0.422 [0.389, 0.385, 0.431, 0.419] , which are fed by the high TN levels in Streams 4, 6B and 6C, are somewhat higher than the levels in the main Harbor, but still significantly lower than the levels in the streams themselves (Table 2, Figure 2). It should be noted that these two stations in Polpis Harbor (NAN-5 {Polpis west} and NAN-6 {Polpis east}) do show an increased TN concentration compared to levels observed in 2014. TN levels remain above the nitrogen threshold for these basins, although total chlorophyll-a was still relatively low in 2015. Total pigment at Stations NAN-5 and NAN-6 were slightly higher in 2015 compared to 2014 reflecting the slightly higher TN in that year and warm summer conditions in 2015. Overall, TN concentrations in Nantucket Harbor were slightly higher in 2015 (0.381 mg/L) compared to summer 2014 (0.324 mg/L). As such it is important to continue summer water quality monitoring and watershed based nutrient management. However a full evaluation of the streams would be to add stream volumetric flow to the stream sampling such that nitrogen load to the harbor could be monitored, as load is associated with the harbor TN levels. Relative to the 2015, 2014, 2013, 2012 and 2010 data sets, results indicate that within Long, Hummock and Miacomet ponds, there is a general gradient of nutrient (N and inorganic P) and chlorophyll concentrations from high levels in the upper, more enclosed 22 and poorly flushed reaches of the estuaries to lower concentrations closer to the outlets where flushing is more effective (Figure 14), although the gradient appears to be a bit flatter in 2015 for both Hummock Pond and Long Pond. Based on average TN values in Hummock Pond, water quality in 2015 appears improved over prior years, but not enough to meet the nitrogen threshold needed for restoration. In Miacomet Pond, while average TN values in 2014 were generally similar to 2013 (0.982 mg/L vs. 0.962 mg/L), TN values in 2015 were even higher (1.202 mg/L) and chlorophyll-a levels were also significantly higher than in 2014 and 2013. These are very high TN levels for this basin. However, Miacomet Pond in 2015 as in 2014 likely had phytoplankton production (e.g. chlorophyll-a) also controlled by phosphorus levels, as the salinity has declined to ~0.1 ppt, due to the extended time since this basin was opened to the tides. As TP and PO4 samples were collected in parallel with the nitrogen fractions in the 2015 surveys of Miacomet Pond, it was possible to assess nitrogen versus phosphorus significant to eutrophication from the N to P ratios as well as Carbon to Nitrogen (C/N) ratios. These field ratios are compared to the idealized Redfield Ratios (C:N:P, 106:16:1) to get a first approximation of the degree to which N or P maybe structuring the pond. Interestingly, C/N ratios remain relative consistent from the head to the lowest basin of the pond closest to the ocean (MP3 - MP1 - MP2, C/N ratio 6.5, 6.8, 6.5 respectively, Redfield C/N ratio is 6.62). This supports the contention that phytoplankton comprise almost all of the particulate matter in the pond. The nutrient data showed significant variation between the pond basins, with N/P ratios lower at the head and increasing to the middle and lower portions (MP3 - MP1 - MP2, N/P ratio 16.9, 36.9, 34.4 respectively, Redfield N/P ratio is 16). Ratios significantly greater than 16 indicate that phosphorus additions likely result in increased eutrophication and that Phosphorus should be a focus of pond management. This is the case in the middle and lower pond. The upper pond appears to be sensitive to both nitrogen and phosphorus, such that overall both nutrient need to be monitored and considered for management of Miacomet Pond. More specifically, use of Redfield ratio information in freshwater is greatly enhanced when nutrient ratios are examined together with controlled biotests (bottle tests, mesocosms) with different levels of P and N amendments to natural phytoplankton community. These types of biotests were employed by the Coastal Systems Program for an assessment of Oyster Pond in Falmouth specifically to better determine the degree of N or P limitation in that coastal salt pond for nutrient management purposes. Comparison of algal biotest results and chemical nutrient concentrations in lakes has suggested that a mass N:P ratio above 17-20 indicates P limitation, a ratio below 10 indicates N limitation and values between 10 and 17 indicate that either of the nutrients may be limiting." (Petri Ekholm, Finnish Environment Institute, 2008). That there is a clear difference between the N/P ratios in the upper part of the pond versus the lower part of the pond and considering the N/P ratio at the uppermost station is ~16 and the lower station is significantly >16 (see table below) suggests that the upper portion of Miacomet could be either N limited or P limited while the middle and lower portions of the system are likely P limited. A more detailed examination of N and P cycling is warranted to ascertain which is playing a bigger role in the nutrient cycling of the pond system as a whole. At present, this pond appears to be shifting from a eutrophic brackish water system to a eutrophic freshwater ecosystem and should potentially be managed as such, taking into consideration which nutrient is dominant (N vs. P). However, management must include that periodic overwash from storms could upset the ecological balance of this system if it were managed purely as a freshwater system. 23 Station Id N/P PC/PN DIN/DIP TN/TP organic particulate inorganic total MP-3 16.9 6.5 10.2 16.1 MP-1 36.9 6.8 10.3 34.3 MP-2 34.4 6.5 13.1 32.3 Unlike previous sampling years (2012, 2013, 2014), stream sampling and flow measurement was added to the 2015 monitoring program in Nantucket Harbor, particularly due to the interest in achieving the MEP TN threshold in Polpis Harbor (NAN-6 is considered the MEP sentinel station and with a TN threshold concentration of 0.355 mg/L for restoration). Samples collected from 3 stream stations (ST3, ST4, ST6B) discharging to Polpis Harbor showed high TN concentrations (1.218, 1.060, 1.10 mg/L respectively, based on data presented in Table 2). It should be noted that the average TN concentration for station ST3 is 1.038 mg/L if the 8/31/2015 sampling date (TN concentration = 0.499 mg/L) is included in the calculation. It is possible that sample data for that one sampling date is abnormally low compared to the results from the three other sampling dates at that station (0.939-1.554 mg/L). As such, the 8/31/2015 sample result was not utilized to calculate summer average TN concentration for station 3. Interestingly, stream sampling site ST4 and ST6B were sampled once (June) in 2010 and showed TN concentrations of 1.200 and 2.139 mg/L respectively. The 2010 concentrations are consistent with the high concentrations observed in 2015 and as such, warrants continued monitoring of stream nutrient concentrations and stream flow discharging to Polpis Harbor specifically. Management of these flows and nutrient loads may help to achieve the MEP TN threshold for Polpis Harbor at the sentinel station (NAN-6). In addition to nutrient sampling, the Town of Nantucket staff measured the velocity of water flowing at each sampling location at the time water quality samples were being collected during the summer 2015 field season. While the CSP scientists are unaware of how the velocity and cross-sectional measurements were made, the town provided the critical stream flow values (m3/d) to be coupled with the parallel measurements of total nitrogen concentration data to calculate TN load from these streams to Polipis Harbor in summer 2015. The flow determined for each sampling day was then used to determine load for a representative month. The flows and loads are provided below: 24 Measured TN Load TN Load Representative Sample ID Date Flow Month (m3/d)(kg/day)(kg/month) ST3 6/8/2015 365 0.424 12.7 June ST3 7/6/2015 248 0.385 11.9 July ST3 8/3/2015 127 0.119 3.7 August ST3 8/31/2015 40 0.020 0.6 September ST4 6/8/2015 2040 2.020 60.6 June ST4 7/6/2015 1771 1.739 53.9 July ST4 8/3/2015 0 0.000 0.0 August ST4 8/31/2015 208 0.213 6.4 September ST6B 6/8/2015 696 0.586 17.6 June ST6B 7/6/2015 805 1.450 44.9 July ST6B 8/3/2015 187 0.151 4.7 August ST6B 8/31/2015 87 0.082 2.5 September Combining the high TN concentrations with relatively large flows measured at ST4 and ST6B, it becomes clear that a relatively large TN load can be introduced to Polpis Harbor from the stream sites on a monthly basis. It is important to note that the large loads presented would actually be the lowest loads of the year as precipitation during the summer is typically much lower than in the winter and spring. Given this first approximation of the TN loads entering Polpis Harbor via streams, it would clearly be worth continuing measuring flow and nitrogen sampling in coming years of monitoring. Additional estuarine stations (ORS-2,3,4,5,6) were added to the sampling stations in Nantucket Harbor and Madaket Harbor (ORS-1) specifically to monitor water quality in the vicinity of potential sites for oyster aquaculture. These stations have never previously been sampled so it is not possible to compare 2015 results to past years water quality, however, 2015 results can serve as the beginning of establishing a baseline for gauging changes in future years. Station concentrations are generally consistent with the water quality from nearby long term monitoring stations. In the future a detailed interpretation of the data collected at these stations will be possible once more data becomes available. Three stations sampled (ORS-1,5,6) are in addition to the stations identified prior to the summer 2015 sampling (e.g. Madaket, DucksHolm, Polpis). Additional analysis will be useful as additional data/information becomes available. As noted about past years monitoring results, in reviewing the multi-year monitoring dissolved oxygen data, it does not appear that there is sufficient temporal sampling in any one year to capture the critical minimum oxygen levels. Therefore, while assessment of the oxygen levels in each estuary was performed, it will be necessary to conduct a multi-year composite analysis once sufficient data has been collected. It is also possible to strengthen the dissolved oxygen data base in specific estuarine basins as each years monitoring results are assessed through the deployment of continuously recording DO sensors. However this should only be performed on an “as needed basis” rather than as part of the long-term monitoring program. We have made some recommendations which we have noted at the end of the discussion section. 25 Table 2. Summary of Stream Water Quality Parameters (ST3,ST4,ST6B) and stations associated with potential oyster aquaculture locations (ORS1,2,3,4,5,6), 2015 Nantucket Sampling Program. Avg.Avg.Avg.Avg.Avg.Avg.Avg.Avg.Avg.Avg.Avg.Avg.Avg. Sample ID Date Embayment PO4 NH4 Nox DIN DON TDN POC PON TON TN Chla Phaeo Total Pig (mg/L)(mg/L)(mg/L)(mg/L)(mg/L)(mg/L)(mg/L)(mg/L)(mg/L)(mg/L)(ug/L)(ug/L)(ug/L) ST3 6/8/2015 ND 0.011 0.012 0.056 0.068 0.369 0.437 9.117 0.724 1.093 1.160 2.334 4.934 7.267 ST3 7/6/2015 STREAMS TO POLPIS 0.012 0.007 0.052 0.059 0.369 0.429 19.465 1.126 1.495 1.554 0.884 2.088 2.971 ST3 8/3/2015 STREAMS TO POLPIS 0.021 0.004 0.049 0.052 0.330 0.382 10.349 0.557 0.886 0.939 0.025 0.757 0.782 ST3 8/31/2015 STREAMS TO POLPIS 0.010 0.010 0.050 0.059 0.229 0.289 4.055 0.211 0.440 0.499 0.476 5.067 5.543 ST4 6/8/2015 ND 0.037 0.010 0.001 0.011 0.942 0.953 0.539 0.037 0.979 0.990 0.612 1.536 2.148 ST4 7/6/2015 STREAMS TO POLPIS 0.044 0.010 0.000 0.010 0.935 0.945 0.454 0.037 0.972 0.982 0.261 0.652 0.913 ST4 8/3/2015 STREAMS TO POLPIS 0.168 0.026 0.002 0.028 0.975 1.003 4.852 0.243 1.218 1.246 0.109 0.482 0.591 ST4 8/31/2015 STREAMS TO POLPIS 0.077 0.020 0.001 0.021 0.905 0.926 1.596 0.098 1.003 1.024 1.104 1.266 2.370 ST6B 6/8/2015 STREAMS TO POLPIS 0.024 0.011 0.000 0.011 0.649 0.660 3.694 0.182 0.831 0.842 1.310 2.059 3.369 ST6B 7/6/2015 STREAMS TO POLPIS 0.166 0.007 0.001 0.007 0.790 0.797 22.908 1.003 1.793 1.801 0.329 0.745 1.074 ST6B 8/3/2015 STREAMS TO POLPIS 0.012 0.014 0.001 0.015 0.322 0.337 11.321 0.469 0.791 0.806 0.200 0.519 0.719 ST6B 8/31/2015 STREAMS TO POLPIS 0.026 0.077 0.014 0.091 0.411 0.502 9.627 0.443 0.854 0.945 3.178 7.018 10.196 Avg.Avg.Avg.Avg.Avg.Avg.Avg.Avg.Avg.Avg.Avg.Avg.Avg. Sample ID Date Embayment PO4 NH4 Nox DIN DON TDN POC PON TON TN Chla Phaeo Total Pig (mg/L)(mg/L)(mg/L)(mg/L)(mg/L)(mg/L)(mg/L)(mg/L)(mg/L)(mg/L)(ug/L)(ug/L)(ug/L) ORS1 6/9/2015 MADAKET 0.037 0.015 0.005 0.020 0.287 0.307 0.849 0.119 0.406 0.426 3.376 4.160 7.536 ORS1 7/6/2015 MADAKET HITHER CREEK 0.025 0.000 0.014 0.014 0.373 0.388 1.072 0.231 0.604 0.618 6.118 4.891 11.009 ORS2 6/9/2015 OLD NORTH WHARF 0.014 0.019 0.000 0.019 0.200 0.219 0.563 0.090 0.290 0.309 2.855 2.202 5.057 ORS2 7/6/2015 OLD NORTH WHARF 0.016 0.004 0.007 0.011 0.287 0.298 0.532 0.086 0.373 0.384 1.733 1.453 3.186 ORS2 8/3/2015 OLD NORTH WHARF 0.019 0.017 0.011 0.028 0.254 0.282 0.350 0.059 0.313 0.341 0.661 1.806 2.467 ORS2 9/2/2014 OLD NORTH WHARF 0.026 0.020 0.001 0.021 0.225 0.246 0.407 0.072 0.297 0.318 1.523 1.940 3.463 ORS3 6/9/2015 MONOMOY CREEKS 0.024 0.014 0.036 0.050 0.294 0.344 0.473 0.077 0.371 0.421 1.563 2.419 3.983 ORS3 7/6/2015 MONOMOY CREEKS 0.028 0.029 0.047 0.076 0.429 0.504 0.522 0.082 0.511 0.587 1.212 1.491 2.703 ORS4 8/3/2015 PIMENYS POINT 0.012 0.015 0.002 0.016 0.369 0.385 0.373 0.064 0.433 0.449 0.909 1.193 2.102 ORS4 9/2/2014 SHIMMO 0.026 0.056 0.003 0.059 0.214 0.273 0.596 0.109 0.323 0.382 2.712 2.476 5.188 ORS5 8/3/2015 DUCKS HOLM 0.009 0.012 0.003 0.015 0.460 0.475 0.351 0.063 0.522 0.537 0.904 0.849 1.753 ORS5 9/2/2014 DUCKS HOLM 0.014 0.013 0.000 0.013 0.302 0.315 0.493 0.089 0.391 0.404 1.237 2.264 3.501 ORS6 8/3/2015 POLPIS 0.020 0.013 0.000 0.013 0.533 0.546 0.683 0.112 0.645 0.658 1.589 2.614 4.204 ORS6 9/2/2014 POLPIS 0.035 0.050 0.000 0.050 0.299 0.349 0.561 0.094 0.393 0.443 1.451 2.696 4.147 26 Trophic State of the Estuaries of Nantucket Island The Trophic State of an estuary is a quantitative indicator of its nutrient related ecological health and is based on concentrations of inorganic and organic Nitrogen, water clarity (Secchi Depth), lowest measured concentrations of Dissolved Oxygen (average of lowest 20% of measurements), and Chlorophyll-a pigments (surrogate for phytoplankton biomass/blooms). Trophic health scales generally range from Oligotrophic (healthy-low nutrient) to Mesotrophic (showing signs of deterioration of health due to nutrient enrichment) to Eutrophic (habitats impaired and degraded, high nutrient and organic matter). The Trophic Health Index Score used here is a standard numerical scale based on criteria for open water embayments and uses the above mentioned measured parameters to create a habitat quality scale (Howes et al. 1999, http://www.savebuzzardsbay.org). For the estuaries within the Town of Nantucket, a trophic index score was calculated for each sampling location for each year (2010, 2012, 2013, 2014 and 2015) using the summer monitoring data. The Index scores were calculated in 2 ways, one which included the low dissolved oxygen for each year in the index ("with DO", Table 7) and one which excluded the oxygen metric ("without DO", Table 8). The reason for this dual approach is that in some estuaries, such as those on Nantucket, there are only periodic depletions in bottom water dissolved oxygen, generally related to meteorological events acting on nutrient enriched basins. While these short-term depletions have important ecological consequences, they are difficult to capture in programs that sample 4 or 5 dates per summer. In these cases, inclusion of the oxygen can bias the Index upwards (i.e. higher quality) because of the greater probability of capturing high versus low oxygen events. This bias was found in the previous analysis of the 2010 dataset, as well as for other estuaries in s.e. Massachusetts. However, this is not always the case and there was no substantive difference between the "with DO" and "without DO" Index scores based on the 2013 and 2014 data, although the analysis is presented for informational purposes herein (Tables 7a,b and 8a,b). It should be noted that to the extent the bias exists in a given year, it relates only to the oxygen data, the other water quality parameters do not change as rapidly as dissolved oxygen and therefore the sampling program adequately captures accurate concentrations of nutrient related metrics (DO changes by the hour). Given that inclusion of oxygen data did not generally change the bay health rank, it did yield a change in the numerical value. For the present analysis the standard Index was used for assessment and the Health Status was determined for each site based on the data collected during the sampling events. The ranges of Index scores that fall within a particular Health Status determination are given at the bottom of both Tables 7 and 8 with the Index values and description for each monitoring station. Figures 18-22 show the distribution of Health Status throughout each estuary based on each of the 5 years of monitoring (2010, 2012, 2013, 2014, 2015). Numerical results are color coded for ease of interpretation. The colors of each triangle represent the Bay Health Index status of each site and follow the designation scheme below: 27 Color Health Status Blue High Quality Blue/Yellow High-Moderate Yellow Moderate Yellow/Red Moderate/Fair Red Fair/Poor The integrated water quality scores, as represented by the Index were generally consistent between all 5 years of monitoring, although change at some sites was observed. This relative stability is typical as nutrient related health does not generally change rapidly unless a significant alteration has occurred to the watershed nitrogen loading or to tidal flushing of a basin (e.g. Hummock Pond). However, 2 systems do appear to show a potential shift in nitrogen related health over the past 5 years, Hither Creek and lower Hummock Pond (see below). Based upon the results it is possible to assess the nutrient related health of the basins within each of the 5 estuarine systems within the Nantucket Water Quality Monitoring Program. The following assessments rely mainly on the Index "with DO" scores as it appears to accurately represent current conditions: Madaket Harbor Madaket Harbor main basin is supporting a high level of nutrient related water quality. It has been the more enclosed basins of Hither Creek and Long Pond with their reduced tidal flushing that have nitrogen impairment problems. Water quality generally changes gradually, unless there has been a major change in loading or flushing. Within the Madaket Harbor/Long Pond watershed there has been a significant change in the nitrogen sourced at the Town Landfill. The Landfill has recently been undergoing management actions that reduce nitrogen loading to the groundwater, hence to upper Long Pond. It appears that the long-term gradual improvement within the upper portions of this complex estuary is consistent with a lowering of nitrogen loading. Over the 5 years of monitoring, Hither Creek (Station 1), which receives discharge from Long Pond via Madaket Ditch, has consistently supported the poorest “health” status within the Madaket Estuary (Table 7, 8, Figure 18). Hither Creek is clearly nitrogen enriched and showing continuing impairment based on a variety of parameters. However, over the past 5 years the Index indicates that this basin has improved slightly each year, going from fair-poor water quality and improving in a step-wise manner to moderate water quality in 2014 and 2015. The main basin of Madaket Harbor is showing relatively high water quality in each year but also shows a possible improvement from 2010 to 2012 and has been stable at high water quality in more recent samplings. It appears that Station 2, near the outlet to Hither Creek is receiving low quality waters on the ebb tide from Hither Creek and that can modify water quality at this nearshore location. The inter-annual difference at this site likely stems from the degree that the poor water quality plume from Hither Creek was sufficient to shift its status in previous years. In contrast, the offshore sites (3 & 4) support high quality waters resulting from low nitrogen inputs and very high rates of water exchange. The 5 year positive trend in health index is at least partially the result of the reduced loading from the landfill to upper Long Pond and an improvement in the ebbing waters through Madaket Ditch. This trend 28 is consistent with the upper basin feeding Madaket Ditch, although the lower Long Pond Station (#5) has varied from year to year without a clear trend. The cause of this inter- annual variation and the mechanism for the large difference between the 2 Long Pond stations in needs further analysis. If the improvement in Hither Creek continues, it is possible that the TMDL for Madaket Harbor may be met, and may reduce some of the need for other nitrogen management actions. However, it will not be sufficient to meet the TMDL for Long Pond (see below). Long Pond Long Pond is a large tributary basin to Madaket Harbor, which receives tidal flow through the artificial connection of Madaket Ditch. Given the structure of the basin and its watershed, Long Pond operates semi-independently from Madaket Harbor (Figure 18). Unlike Madaket Harbor which is marine, Long Pond is a brackish water system resulting from groundwater inflows and its restricted tidal exchange. Long Pond’s Bay Health scores for both stations (5 & 6) in the 4 years of monitoring (2010, 2012, 2013, 2014) clearly indicate poor nutrient related water quality. It is nearly certain that the water quality of Hither Creek is partially dependent on the nitrogen load from Long Pond via Madaket Ditch during the ebb tide. However, the Town’s management of the Landfill, which should reduce the nitrogen load from this source is temporally consistent with improvements in the water quality Index for Long Pond and the lower TN levels. TN levels in 2015 were almost half that of historical/2010-11 measurements. While continued monitoring will determine the level of improvement, it does appear that there a reduction in N loading may be occurring with beneficial effects. However, even if TN levels stabilize at 2015 levels, the TN is still high and results in poor clarity, algal blooms and nutrient related stress to aquatic resources. It should be noted that the lack of major change in the Health Index for Long Pond results in part from the relative coarseness of the Index, where sometimes large index score changes are required to change the Index value. The analysis of key metrics (Chlorophyll-a, water clarity-Secchi and total nitrogen) individually do show improving water quality at stations 5 and 6 in 2012, 2013,2014 and 2015 compared to 2010 and in the MEP threshold analysis (see analysis and figures above). The issue is that presently there has not been a large enough shift to bring metrics above Health Index thresholds to change the rating significantly. Results from the 2016 should help to determine the level of improvement expected in coming years. Nantucket Harbor Nantucket Harbor with Madaket Harbor are presently supporting the highest water quality of Nantucket's estuaries. The main basin of Nantucket Harbor is supporting high quality waters, with only a periodic small level of decline in the uppermost basin, Wauwinet basin (Figure 19). Wauwinet basin (station 3) had the highest average total nitrogen values for the Harbor System in 2013 (0.415 mg/L) and 2015 (0.436 mg/L) consistent with its designation as the surrogate for the sentinel station for the main basin and its documented past eelgrass loss. It should be noted that in summer 2016, SMAST station 2A (the official MEP sentinel station for which the nitrogen threshold was established, refer to Figure 15) will be added to the monitoring along with station 3 in order to meet TMDL compliance monitoring criteria. Summer 2015 showed similar water quality in this basin as 2010 and 2012, contrasting with the 2014 results which showed improved chlorophyll-a and TN levels versus prior years. The main driver of the 2015 water quality was a phytoplankton bloom in the upper Harbor, which was relatively large for Nantucket Harbor but only moderate for more enriched estuaries in the region. It is 29 unclear if this will become more commonplace in the future and should be monitored. However, other activities associated with the Harbor (additional sewer hookups, jetty improvement and oyster aquaculture) may offset any underlying trend. A similar pattern was seen in the enclosed sub-basins of Polpis Harbor (East and West) which continue showing moderate impairment and moderate nitrogen enrichment, although appear to have improved over historic conditions. As in Wauwinet, Polpis Harbor showed TN levels similar to 2010 and 2012 which were higher than 2013 and 2014. This variation makes continued monitoring essential to clarify any trends in water quality. However, unlike Wauwinet, Polpis did not show a phytoplankton bloom and supported only moderate-low phytoplankton biomass in 2015 (~4 ug/L) and appears to have attained moderate-high water quality status. While the overall Nantucket Harbor System is generally supporting high quality waters, the variability in the index in Wauwinet and Polpis should be monitored to ascertain the long-term health of these basins and that efforts to restore these basins by the Town continue to move forward to meet the MassDEP TMDL for this system. Overall, Nantucket Harbor appears to be relatively stable from year to year and even with high index scores the higher level metrics support the contention that it is still above its TMDL threshold, as also for Polpis Harbor. Sesachacha Pond Sesachacha Pond is a closed coastal salt pond that has its water quality managed by periodically breaching the barrier beach to open the basin to tidal exchange with the adjacent Atlantic Ocean waters. This management action serves to flush out nutrients and organic matter on the ebb tides and receive saline waters on the flood tides. Sesachacha Pond was evaluated under the Massachusetts Estuaries Project and a nitrogen threshold (0.60 mg/L) was established for restoration of this system. Additionally, the MEP analysis recommended an additional mid-summertime opening as part of the pond management strategy to enhance flushing of the pond and improve water quality to reach the threshold. The water quality monitoring program in 2010, 2012 and 2013 showed that the pond nitrogen levels were converging on the 0.60 mg/L total nitrogen threshold established by the MEP. Total nitrogen (TN) levels dropped significantly from historical levels of 1.20 mg/L to ~0.68 mg/L in 2010 and 2012 and 0.67 mg/L in 2013, with associated improvements in the levels of water clarity and chlorophyll-a. The monitoring data suggest that the pond may still be reaching a new balance, as the limited 3 years of data (2010, 2012 and 2013) show virtually the same TN concentrations in each year. In contrast the 2014 and 2015 results showed a partial return to historic levels of TN, ~0.9 mg/L, which may relate to the quality of the pre- summer opening. Given the prior 3 years, it appears that a solid opening program has the capability to improve the water quality metrics pond-wide to levels near the TMDL nitrogen threshold. Using the Index alone, changes in water quality in Sesachacha Pond over the 2010-2013 period were stabilizing at moderate level of estuarine health, with the past 2 seasons seeing a significant trend toward poor water quality conditions (Figure 20). Additional higher level assessment of Sesachacha Pond initiated by the 2010 monitoring results has been conducted which confirms that the pond was improving by 2013, but was impaired in 2014 consistent with the monitoring results. The 2015 data underscores the reversal of improvement with phytoplankton biomass (as chlorophyll) averaging >10 ug/L at all stations over the summer, indicative of a significant nitrogen enrichment. The high chlorophyll values are consistent with the high TN values in 2014 and 2015. It appears that like other periodically opened ponds, the quality of the opening (amount of water exchanged) controls the level of water quality in the following months. Fortunately, the data indicate that attaining pond openings of the 30 quality of 2012 and 2013 (done under Town supervision) in the future may be sufficient to attain the TMDL for this system. A closer examination of the opening protocol and the linkage to resultant water quality is needed for management of this system. Hummock Pond Hummock Pond is a closed coastal salt pond that is only periodically opened to the ocean to flush out nutrients and organic matter on the ebb tide and receive saline waters on the flood tide. Creating sustained openings that are sufficient to allow exchange of tidal waters for more than 4-5 days has been difficult for this system due to its location on the coast and the large amount of sand migration in the coastal zone which can rapidly reseal the inlet. Hummock Pond is opened at a sufficient frequency to sustain salinity levels in the 4-8 ppt range, with only small inter-annual differences (2012 slightly higher than 2010). The pond supports a small but clear salinity gradient from Station 1 nearest the ocean to Station 7 in the uppermost basin (Head of Hummock). The present non-tidal state and watershed nutrient inputs have resulted in moderate to poor nutrient related water quality throughout the pond, with poor water quality conditions the present norm (2005- 2007, 2010, 2012, 2013, 2014, 2015). There is a small gradient in water quality with moderate to poor conditions near the ocean and poor conditions in the uppermost basins (Figure 21). This gradient stems from the periodic openings and over-wash events. The uppermost basin, Station 7, is approaching fresh/brackish conditions and is currently supporting mainly freshwater plant and animal habitats. This basin is particularly eutrophic with phytoplankton blooms exceeding 70 ug/L (offshore waters are ~2 ug/L). This basin appears to have been artificially connected to the adjacent estuary and is the recipient of much of the freshwater inflow. It is one of the most highly eutrophic basins within the Town of Nantucket. Due to the restricted tidal exchange even the lower basin of Hummock Pond supports moderate to high average chlorophyll levels ~10 ug/L (2010, 2012, 2015). All of the metrics are consistent with a nutrient impaired basin in all years. It should be noted that the lower third of the Hummock Pond Estuary is currently supporting impaired benthic animal habitat even though conditions are the "best" in the overall impaired system. Given previous studies of Hummock Pond it appeared that its nutrient related health was significantly related to the success of its periodic openings. As a result, the Town and Nantucket Land Council undertook an analysis to refine the opening protocol and gauge its effectiveness. The April 2013 opening was the first “experimental” opening and it appeared to result in significant loss of TN and inflow of salt water. The individual metrics and the Health Index for summer 2014 and 2015 appear to support that tidal flushing was improved as nutrient related health was highest in 2014 and 2015 of the years monitored. It also appears that the continued successful inlet openings from April 2014 into 2015 have resulted in additional improvements in water quality from 2014 to 2015, with 2015 showing the lowest TN levels in records back to 2005, although it is still above its threshold value to support high quality habitat. This opening program and associated monitoring around the openings and in the summer should be continued to set metrics for a “successful” opening, to produce a simplified assessment protocol for opening success and to document and further refine the opening protocol for the Town’s on-going program. To date this joint effort has resulted in significant benefits to Hummock Pond water quality and associated natural resources at low cost to the Town. 31 Miacomet Pond Miacomet Pond is a closed coastal salt pond that is seldom (once in the past ten years) opened to the ocean to flush out nutrients and organic matter on the ebb tide and receive saline waters on the flood tide. As a result of the lack of tidal flow and groundwater inputs the pond is presently freshwater, with salinity levels in each of the 4 years of monitoring of <0.6 ppt, reaching a low of 0.1 ppt in 2015. The present non-tidal state and watershed nutrient inputs has resulted in a decline in nutrient related water quality throughout the pond for both nitrogen and phosphorus, with poor water quality conditions the present norm (Figure 22). This can be seen, for example, in the high chlorophyll levels (2010: 12-50 ug/L); 2012: 10-20 ug/L; 2013: 20-26 ug/L; 2014: 23-70 ug/L) several times the levels found in the high quality basins of Nantucket and Madaket Harbors with 2015 continuing the trend (38-53 ug/L) and supporting the highest chlorophyll a levels throughout the pond of the years measured (as opposed to at a single station). All of the metrics are consistent with a nutrient impaired basin. However, as the freshening of this basin has continued, it likely will have to be managed as a transitional freshwater system and will need to be reassessed as such. As salt ponds freshen and become fresh ponds the nutrient causing eutrophication can shift to phosphorus from nitrogen or become both nitrogen and phosphorus (seasonally varying nutrient limitation). Since Miacomet Pond may have storm overwash in the future, it may be necessary for management to create both a nitrogen and a phosphorus budget for this system and to conduct short-term incubations to determine which nutrient is controlling pond health under present and varying salinity conditions. It will be difficult for Miacomet Pond to maintain itself as a purely freshwater system as storm overwash and rising sea level will tend to periodically cause seawater intrusion into its lower basin. An analysis of future conditions for Miacomet Pond as sea level rises may be in order in the near future, as remediation is considered. But at present the system is a highly nutrient impaired aquatic system with poor water quality. Recommendations for Future Monitoring As mentioned in previous years summaries of estuarine water quality across Nantucket, due to the critical importance of dissolved oxygen to the ecological health of an estuarine basin, additional data should be collected using high frequency automated sensors when the low frequency sampling of the monitoring program suggests that a problem may exist in a specific basin. At this point, Polpis Harbor and Wauwinet basin in Nantucket Harbor should be considered for this analysis at some time in the future (e.g. summer 2016). It may also be timely to complete a higher level assessment of Miacomet Pond as that large salt pond has been showing consistently poor water quality and low trophic status indicative of an impaired habitat and is becoming a freshwater basin. However, procedural steps should also be implemented to strengthen the oxygen data base from the on-going monitoring program. Approaches to address these 2 issues are: 1) Deploying in situ oxygen meters (sondes) on the bottom of specific estuaries at several strategic locations for the summer months when periodic hypoxic or anoxic events in bottom waters can occur. 32 2) Long Pond is approaching the time when a detailed analysis of nitrogen entering from the land fill should be conducted, particularly how the land fill remediation is projected to improve water quality in the adjacent estuary. The monitoring results from 2012 - 2015 appear to show a significant reduction in TN over historical conditions and 2010. The TN pattern in 2014 suggested that there may be a restriction to mixing between station 5 and 6 which should be investigated and if possible managed. Additionally, the TN data in 2015 showed a continuing decrease in TN levels with a significant drop from 2014 at both stations in the pond (station 5 {1.481 dropped to 0.697}, station 6 {0.788 dropped to 0.656}). Additionally, it should be noted that the stream stations discharging to Nantucket Harbor (specifically Polpis Harbor) which were not sampled in 2012, 2013 or 2014 were sampled in 2015. With increasing interest in lowering TN concentrations in Polpis Harbor to meet the MEP established TN threshold, it is appropriate to extend stream sampling into the 2016 sampling season given the high concentrations of total nitrogen observed in 2015 that are discharging to this tributary sub-embayment. The utility of these data would be greatly enhanced if sampling was paired with flow measurements to allow determination of both the concentration of stream water and the nitrogen load discharged to the Harbor from each streams watershed and to gage the degree to which the loads these streams contribute to the TN concentration at the sentinel station in Polpis Harbor. While concentrations are high at stations 3, 4 and 6b (1.218, 1.060, 1.184 mg/L respectively) loads may be moderate depending on the flow rate at each stream sampling point. Miacomet continues to show poor and worsening trophic conditions, high TN concentrations at stations 1, 2, and 3 (1.297, 1.318, 0.992 respectively) and extremely high total pigment (CHLA + pheophytin) in 2015. In light of yet another year of decreasing water quality in Miacomet Pond, nitrogen and phosphorus budgets should be developed for Miacomet Pond and a quantitative analysis of N versus P as the driving nutrient of eutrophication. This information will support management actions for managing the pond in its variable salinity state. Hummock Pond appears to have its nutrient related health significantly controlled by the success of its periodic openings. As a result, the Town and Nantucket Land Council undertook an analysis of openings in 2013-2014 to refine the opening protocol and gauge its effectiveness. Critical elements of the protocol were described in a technical memorandum developed by the Coastal Systems Program which summarized two openings that were monitored to gauge effectiveness. The opening protocol should be formalized and rigorously implemented as monitoring clearly showed that if specific conditions are taken into consideration during a given opening, the ensuing opening will tend to be effective thereby having a clear positive impact on water quality in Hummock Pond and indeed Hummock Pond water quality has significantly improved under the revised opening protocol by the Town. Management should continue to focus on how to create the most efficient openings, and evaluate the need for a mid-summer opening in this system. The new opening program and associated monitoring around the openings and in the summer should be continued to set metrics for a “successful” opening and document and further refine the opening protocol for the Town’s on-going program. Additionally, it is critical to carefully document conditions during a given opening (pond water levels before during and after the opening, water quality, wind direction, wave conditions {size and direction}, tidal state {spring vs. neap}, size of opening {depth and width} and duration of opening) in order to continue building up a quantitative basis for 33 refining openings and maximizing the improvement of water quality in Hummock Pond. Similarly, the opening protocol should be implemented for openings of Sesachacha Pond as monitoring has indicated that water quality improved in Sesachacha Pond (2010-2013) compared to historical MEP mean (1992-2005) and that is most likely directly related to the effectiveness of openings as loads into the pond are low and not necessarily decreasing. However, this trend toward restoration has reversed with TN levels in 2014 and 2015 (0.919 and 0.918 mg/L respectively) rising compared to levels in 2010,12,13 (0.684, 0.678, 0.714 mg/L respectively). Details of the openings in 2014 and 2015 should be compiled and compared to the openings completed in 2010, 2012 and 2013 in order to ascertain the difference between openings and future openings in 2016 should be monitored to continue building up the database of what constitutes an effective opening in both Sesachacha Pond and Hummock Pond. The data base will serve to strengthen and refine the Ponds Opening Protocol. Acknowledgements This work is in collaboration with the Town of Nantucket through its Natural Resources Department and the Marine Department. Special thanks go to Kaitlyn Shaw, Town of Nantucket Water Resources Specialist and the Monitoring Program Coordinator and to Jeff Carlson (Director - Natural Resources Department) for the extra efforts that they have provided to ensure sampling success and the maintenance of a high quality monitoring program. In addition, the Nantucket Land Council (Cormac Collier) provided support for assessment of Hummock Pond openings and the development of the new opening protocol, with additional support from Land Council staff. It is through the dedication of these groups and the efforts of Nantucket that Nantucket’s estuaries are being protected and in some cases already moving toward restoration. 34 Table 2a. Summary of Water Quality Parameters, 2015 Nantucket Sampling Program. Values are Station Averages of all sampling events, May-September for sampling sites. It should be noted that TP was only evaluated in Miacomet Pond because of the expected low salinity values in that closed pond and the possibility that the system maybe phosphorous limited rather than nitrogen limited. Further study should investigate the possibility and TP paired with salinity should continue to be monitored during the summer 2016 field season. 2015 Seccchi Secchi 20% Low 20% Low Sample ID Depth Depth as Field DO DO Sat Salinity PO4 TP NH4 Nox DIN DON TDN POC PON TON TN Total Pig (meters)% of WC (mg/L)(%)ppt (mg/L)(mg/L)(mg/L)(mg/L)(mg/L)(mg/L)(mg/L)(mg/L)(mg/L)(mg/L)(mg/L)(ug/L) HUM1 1.50 48%7.13 83%7.43 0.009 --0.004 0.003 0.007 0.350 0.357 1.097 0.182 0.532 0.539 10.50 HUM3 1.50 61%6.82 75%7.11 0.012 --0.005 0.006 0.011 0.402 0.413 1.236 0.209 0.610 0.622 9.41 HUM5 1.00 57%6.87 79%5.45 0.019 --0.005 0.003 0.008 0.359 0.366 1.206 0.192 0.550 0.558 8.58 HUM7 1.30 49%5.65 87%3.33 0.101 --0.089 0.030 0.119 0.349 0.468 0.996 0.154 0.502 0.621 7.07 HUM8 0.70 90%7.13 95%3.90 0.059 --0.005 0.011 0.016 0.366 0.381 1.230 0.195 0.560 0.576 12.82 LONG5 0.70 86%6.60 85%16.02 0.020 --0.012 0.004 0.016 0.378 0.395 2.025 0.302 0.681 0.697 8.95 LONG6 0.60 76%5.78 73%16.01 0.025 --0.006 0.002 0.008 0.369 0.377 1.619 0.280 0.649 0.656 10.78 MH1 1.80 77%4.88 68%29.28 0.021 --0.019 0.006 0.025 0.379 0.404 0.652 0.120 0.499 0.524 4.82 MH2 1.78 100%5.56 78%31.76 0.010 --0.012 0.030 0.042 0.289 0.331 0.482 0.088 0.376 0.418 3.07 MH3 2.40 97%6.57 90%32.00 0.010 --0.005 0.001 0.006 0.236 0.242 0.461 0.082 0.318 0.324 3.00 MH4 2.90 63%6.70 91%32.13 0.015 --0.006 0.002 0.008 0.269 0.277 0.301 0.051 0.321 0.328 2.54 MP1 0.90 50%6.94 83%0.10 0.008 0.084 0.025 0.013 0.038 0.592 0.630 3.870 0.666 1.259 1.297 46.52 MP2 0.70 32%6.10 82%0.11 0.009 0.090 0.042 0.011 0.053 0.593 0.646 3.726 0.671 1.264 1.318 53.40 MP3 1.40 54%7.91 91%0.10 0.017 0.136 0.021 0.057 0.077 0.396 0.473 2.878 0.518 0.914 0.992 37.91 NAN1 ND 62%6.29 88%32.13 0.024 --0.010 0.002 0.012 0.246 0.258 0.437 0.072 0.318 0.330 3.84 NAN2 2.65 49%5.95 85%32.25 0.019 --0.018 0.001 0.019 0.272 0.291 0.474 0.084 0.355 0.374 4.33 NAN3 1.45 27%5.89 86%32.37 0.026 --0.022 0.002 0.024 0.278 0.302 0.716 0.134 0.412 0.436 7.16 NAN4 3.80 65%6.58 91%32.14 0.019 --0.010 0.001 0.011 0.219 0.230 0.357 0.066 0.286 0.297 3.58 NAN5 1.65 85%5.32 76%31.92 0.021 --0.018 0.001 0.019 0.296 0.316 0.578 0.107 0.403 0.422 3.86 NAN6 1.95 73%5.64 81%31.94 0.019 --0.014 0.001 0.015 0.282 0.297 0.555 0.107 0.389 0.404 4.39 NAN7 1.45 76%6.20 86%32.00 0.019 --0.013 0.002 0.015 0.270 0.285 0.628 0.105 0.375 0.390 3.68 NAN8N 1.00 96%5.65 81%31.97 0.016 --0.007 0.002 0.009 0.227 0.236 0.435 0.077 0.304 0.313 3.08 SESA1 0.60 20%7.06 88%11.26 0.202 --0.006 0.003 0.008 0.479 0.487 3.193 0.431 0.910 0.918 11.45 SESA2 0.60 14%6.55 82%11.27 0.202 --0.003 0.002 0.005 0.448 0.454 3.100 0.417 0.865 0.870 10.39 SESA3 0.60 20%6.73 89%11.27 0.211 --0.003 0.002 0.006 0.476 0.481 3.146 0.429 0.904 0.910 11.33 SESA4 0.60 20%6.62 87%11.27 0.210 --0.003 0.003 0.007 0.507 0.514 3.028 0.405 0.912 0.919 11.10 35 Table 2b. Summary of Water Quality Parameters, 2014 Nantucket Sampling Program. Values are Station Averages of all sampling events, May-September for sampling sites. Seccchi Secchi Depth Depth as 20% Low 20% Low Salinity PO4 NH4 Nox DIN DON TDN POC PON TON TN Total Pig Sample ID (meters)% of WC DO (mg/L)Sat (%)ppt (mg/L)(mg/L)(mg/L)(mg/L)(mg/L)(mg/L)(mg/L)(mg/L)(mg/L)(mg/L)(ug/L) HUM1 1.37 56%8.41 73%6.12 0.012 0.029 0.004 0.033 0.428 0.461 1.230 0.191 0.618 0.651 5.480 HUM3 1.05 61%8.35 75%5.72 0.012 0.023 0.006 0.029 0.402 0.431 1.329 0.212 0.614 0.643 5.262 HUM5 1.08 58%8.38 73%4.75 0.014 0.014 0.003 0.017 0.401 0.418 9.925 0.235 0.636 0.653 6.534 HUM7 0.94 41%8.44 77%2.65 0.047 0.054 0.020 0.071 0.444 0.515 2.400 0.358 0.801 0.873 11.875 HUM8 0.79 35%8.36 69%3.62 0.030 0.014 0.003 0.017 0.526 0.543 1.417 0.212 0.738 0.755 6.240 LONG5 0.75 75%7.62 53%14.12 0.032 0.080 0.012 0.092 0.975 1.066 2.354 0.415 1.390 1.481 8.988 LONG6 0.73 75%7.69 69%15.06 0.014 0.040 0.011 0.051 0.420 0.472 1.841 0.316 0.737 0.788 7.342 MH1 1.74 86%7.14 69%28.03 0.019 0.046 0.010 0.057 0.270 0.326 0.616 0.119 0.389 0.445 3.431 MH2 2.50 100%7.14 68%31.01 0.010 0.024 0.002 0.026 0.243 0.269 0.433 0.079 0.321 0.347 1.674 MH3 2.26 91%7.24 68%31.40 0.011 0.023 0.001 0.024 0.217 0.241 0.891 0.135 0.352 0.376 2.701 MH4 2.66 57%7.38 75%31.53 0.012 0.016 0.007 0.020 0.174 0.194 0.340 0.059 0.233 0.254 1.489 MP1 1.38 85%8.41 63%0.13 0.018 0.050 0.003 0.053 0.522 0.575 1.967 0.289 0.811 0.864 9.932 MP2 1.87 63%8.51 71%0.12 0.009 0.035 0.002 0.036 0.568 0.604 1.170 0.180 0.748 0.784 5.326 MP3 0.87 65%8.46 58%0.10 0.049 0.038 0.038 0.077 0.594 0.671 4.437 0.626 1.220 1.297 18.068 NAN1 3.35 64%7.23 77%31.36 0.015 0.017 0.002 0.019 0.201 0.220 0.380 0.063 0.265 0.284 1.311 NAN2 3.06 52%7.17 73%31.42 0.017 0.021 0.003 0.024 0.210 0.234 0.493 0.080 0.290 0.314 1.977 NAN3 3.10 51%6.98 75%31.42 0.016 0.020 0.001 0.020 0.225 0.245 0.631 0.100 0.325 0.345 3.125 NAN4 3.00 56%7.27 81%31.49 0.017 0.017 0.001 0.018 0.180 0.198 0.439 0.079 0.259 0.277 1.659 NAN5 2.13 90%7.10 69%30.99 0.016 0.016 0.003 0.019 0.248 0.267 0.756 0.122 0.370 0.389 3.223 NAN6 2.38 85%7.09 70%31.08 0.016 0.013 0.002 0.015 0.258 0.272 0.626 0.105 0.363 0.378 2.963 NAN7 1.79 80%7.26 73%31.23 0.020 0.022 0.001 0.023 0.168 0.190 0.656 0.104 0.271 0.294 2.691 NAN8N 2.09 99%7.16 74%31.29 0.016 0.015 0.002 0.017 0.188 0.205 0.356 0.062 0.250 0.267 1.267 SESA1 1.17 24%7.87 74%12.26 0.105 0.033 0.007 0.040 0.590 0.630 1.794 0.288 0.878 0.919 7.112 SESA2 1.23 24%7.86 70%12.23 0.111 0.038 0.010 0.049 0.531 0.579 2.154 0.352 0.883 0.931 7.116 SESA3 1.19 32%7.86 75%12.23 0.106 0.030 0.009 0.039 0.603 0.642 1.871 0.296 0.899 0.938 5.852 SESA4 1.22 32%7.83 72%12.25 0.108 0.030 0.009 0.039 0.572 0.611 1.808 0.290 0.862 0.902 5.407 36 Table 2c. Summary of Water Quality Parameters, 2013 Nantucket Sampling Program. Values are Station Averages of all sampling events, May-October for estuarine and harbor sites. 2013 Secchi Secchi 20% Low 20% Low Station Depth Depth Depth DO DO Salinity PO4 NH4 N0x DIN DON PON TON TN T-Pig I.D.m m %WC mg/L %Sat ppt mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L ug/L HUM-1 2.6 1.0 0.4 5.86 63%0.9 0.029 0.030 0.018 0.047 0.554 0.169 0.722 0.769 8.2 HUM-3 2.4 1.0 0.4 5.20 56%0.8 0.034 0.075 0.016 0.091 0.571 0.165 0.736 0.827 7.2 HUM-5 2.2 0.6 0.3 4.20 45%0.5 0.073 0.063 0.026 0.088 0.575 0.217 0.793 0.881 8.3 HUM-7 3.5 0.6 0.2 4.08 44%0.5 0.061 0.077 0.012 0.089 0.408 0.674 1.081 1.170 16.9 HUM-8 2.2 0.6 0.3 3.32 36%0.4 0.079 0.042 0.018 0.061 0.672 0.331 1.004 1.064 7.9 LONG-5 1.1 0.7 0.7 5.87 75%11.9 0.009 0.015 0.008 0.022 0.358 0.328 0.686 0.709 8.1 LONG-6 1.0 0.7 0.7 3.82 49%12.7 0.005 0.017 0.008 0.025 0.561 0.294 0.855 0.880 9.9 MH1 2.2 1.7 0.8 4.36 61%25.7 0.019 0.047 0.019 0.065 0.374 0.134 0.508 0.573 4.2 MH2 1.9 1.8 1.0 5.25 74%30.6 0.012 0.021 0.004 0.025 0.215 0.083 0.298 0.323 1.8 MH3 2.0 2.0 1.0 5.25 74%31.0 0.011 0.014 0.005 0.019 0.209 0.087 0.295 0.314 2.2 MH4 4.5 3.0 0.7 5.82 82%31.3 0.013 0.015 0.007 0.023 0.194 0.062 0.256 0.278 1.7 MP1 1.9 1.0 0.6 5.46 66%0.2 0.009 0.015 0.006 0.020 0.481 0.290 0.771 0.792 19.5 MP2 3.1 1.2 0.4 4.22 51%0.3 0.014 0.029 0.022 0.051 0.429 0.555 0.985 1.036 20.2 MP3 1.6 0.9 0.6 5.20 63%0.1 0.049 0.036 0.104 0.143 0.378 0.540 0.917 1.058 26.2 NAN1 5.5 3.2 0.6 5.10 74%31.2 0.014 0.015 0.003 0.018 0.182 0.062 0.244 0.262 2.6 NAN2 6.0 2.9 0.5 4.80 70%31.1 0.014 0.019 0.006 0.024 0.231 0.090 0.321 0.345 3.7 NAN3 6.2 2.6 0.4 3.48 50%30.9 0.019 0.016 0.004 0.020 0.241 0.154 0.395 0.415 6.4 NAN4 4.9 3.1 0.6 5.66 82%31.3 0.016 0.017 0.004 0.021 0.226 0.070 0.295 0.317 2.9 NAN5 2.3 1.9 0.8 3.90 57%30.1 0.018 0.012 0.005 0.017 0.208 0.159 0.368 0.385 5.6 NAN6 2.7 2.0 0.8 3.26 47%30.5 0.016 0.023 0.004 0.026 0.221 0.153 0.374 0.401 5.9 NAN7 2.5 1.9 0.8 5.02 73%31.1 0.013 0.013 0.004 0.017 0.183 0.122 0.305 0.323 4.6 NAN8 3.2 2.1 0.9 4.96 72%31.1 0.013 0.028 0.004 0.032 0.189 0.084 0.272 0.304 2.9 SES 1 4.9 2.1 0.4 5.83 79%17.1 0.044 0.045 0.011 0.055 0.533 0.125 0.658 0.714 4.7 SES 2 4.3 2.4 0.6 5.2 71%17.0 0.043 0.025 0.008 0.034 0.477 0.110 0.587 0.621 4.1 SES 3 4.5 2.5 0.6 5.6 75%17.0 0.046 0.031 0.011 0.042 0.512 0.109 0.621 0.663 3.8 SES 4 3.9 2.6 0.7 5.6 76%17.0 0.040 0.034 0.013 0.046 0.518 0.111 0.630 0.677 3.8 37 Table 2d. Summary of Water Quality Parameters, 2012 Nantucket Sampling Program. Values are Station Averages of all sampling events, May-October for estuarine and harbor sites. Stream sites were sampled once in June (see Table 1b). Secchi Secchi 20% Low 20% Low Station Depth Depth DO DO Salinity PO4 NH4 N0x DIN DON PON TON TN T-Pig I.D.m %WC mg/L %Sat ppt mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L ug/L HUM-1 1.0 44%6.27 79%7.6 0.020 0.044 0.006 0.050 0.439 0.178 0.616 0.666 8.7 HUM-3 1.2 58%6.20 79%7.0 0.029 0.039 0.003 0.042 0.573 0.249 0.822 0.863 8.3 HUM-5 0.8 44%6.56 82%6.3 0.030 0.043 0.004 0.047 0.540 0.283 0.824 0.871 12.7 HUM-7 0.7 21%5.76 70%4.8 0.011 0.085 0.031 0.117 0.546 0.638 1.184 1.301 27.2 HUM-8 0.6 53%6.51 81%6.0 0.030 0.054 0.005 0.058 0.534 0.352 0.885 0.944 17.5 LONG-5 0.6 58%5.49 71%16.8 0.067 0.063 0.007 0.069 0.441 0.503 0.944 1.013 18.3 LONG-6 0.5 51%5.13 67%18.6 0.027 0.049 0.008 0.057 0.437 0.373 0.810 0.867 7.7 MH1 1.7 70%6.88 98%26.8 0.026 0.115 0.015 0.131 0.332 0.192 0.525 0.655 9.6 MH2 2.3 100%8.16 115%30.9 0.015 0.078 0.010 0.088 0.272 0.084 0.356 0.444 1.8 MH3 2.4 100%7.55 104%31.6 0.018 0.063 0.011 0.074 0.217 0.065 0.282 0.356 1.8 MH4 3.7 90%8.35 119%31.6 0.019 0.032 0.009 0.041 0.189 0.068 0.257 0.297 2.0 MP1 1.5 97%7.14 79%0.3 0.007 0.057 0.004 0.061 0.546 0.221 0.767 0.828 10.8 MP2 1.5 67%7.24 80%0.4 0.005 0.070 0.012 0.082 0.509 0.290 0.799 0.880 20.3 MP3 1.0 81%7.64 92%0.1 0.045 0.109 0.011 0.120 0.381 0.450 0.830 0.950 18.3 NAN1 3.5 73%5.22 74%31.6 0.020 0.045 0.011 0.056 0.210 0.070 0.279 0.335 3.8 NAN2 2.9 62%5.91 85%31.6 0.022 0.057 0.009 0.066 0.213 0.091 0.304 0.364 3.7 NAN3 2.4 40%5.86 87%31.8 0.027 0.035 0.008 0.044 0.261 0.117 0.371 0.411 4.0 NAN4 2.9 63%6.29 90%31.6 0.017 0.031 0.007 0.038 0.212 0.094 0.306 0.344 3.6 NAN5 1.7 76%5.96 83%31.5 0.019 0.046 0.007 0.053 0.233 0.133 0.366 0.419 14.9 NAN6 2.1 76%5.50 77%31.5 0.019 0.042 0.006 0.048 0.289 0.147 0.436 0.484 6.3 NAN7 2.0 80%6.10 86%31.5 0.021 0.049 0.008 0.057 0.217 0.105 0.323 0.379 4.2 NAN8 1.9 100%5.20 74%31.5 0.017 0.050 0.006 0.057 0.225 0.090 0.315 0.371 3.6 SES 1 2.3 51%5.49 77%24.7 0.064 0.042 0.010 0.051 0.497 0.130 0.627 0.678 5.8 SES 2 2.5 52%""24.7 0.065 0.087 0.014 0.101 0.405 0.120 0.525 0.627 5.1 SES 3 2.8 87%""24.7 0.063 0.053 0.007 0.060 0.417 0.107 0.524 0.584 4.2 SES 4 2.7 77%""24.8 0.062 0.060 0.010 0.070 0.456 0.142 0.599 0.668 4.5 38 Table 2e. Summary of Water Quality Parameters, 2010 Nantucket Sampling Program. Values are Station Averages of all sampling events, May-October for estuarine and harbor sites. Stream sites were sampled once in June (see Table 1a). Station ID Secchi Depth (m) Secchi Depth as % WC 20% Low D.O. (mg/L) 20% Low % Sat Salinity ppt PO4 mg/L NH4 mg/L NOX mg/L DIN mg/L DON mg/L PON mg/L TON mg/L TN mg/L Total Pig (ug/L) HUM1 1.4 54.4% 4.81 56.0% 7.3 0.013 0.021 0.002 0.023 0.425 0.168 0.592 0.616 12.30 HUM3 1.3 61.5% 4.99 59.8% 6.4 0.012 0.022 0.003 0.025 0.380 0.184 0.564 0.589 11.04 HUM5 0.9 44.2% 4.65 56.1% 5.3 0.015 0.020 0.003 0.023 0.430 0.313 0.743 0.766 27.03 HUM7 0.9 23.4% 3.89 45.0% 4.0 0.284 0.070 0.069 0.139 0.628 1.020 1.647 1.786 67.66 HUM8 0.7 51.0% 4.80 56.5% 4.4 0.025 0.031 0.008 0.039 0.584 0.360 0.944 0.983 33.02 LONG5 0.6 48.5% 4.77 62.9% 16.0 0.071 0.009 0.002 0.011 0.480 0.894 1.374 1.385 18.08 LONG6 0.6 48.8% 4.76 62.9% 15.9 0.028 0.022 0.003 0.026 0.567 1.452 2.019 2.044 24.21 MH1 1.6 67.1% 3.00 40.1% 26.8 0.024 0.045 0.005 0.050 0.316 0.260 0.576 0.626 14.20 MH2 1.9 93.9% 3.52 47.9% 29.7 0.014 0.024 0.003 0.027 0.264 0.145 0.409 0.436 9.37 MH3 2.3 100.0% 4.39 55.5% 30.8 0.011 0.024 0.002 0.026 0.213 0.084 0.297 0.324 6.14 MH4 3.8 58.3% 4.27 55.6% 31.1 0.015 0.024 0.002 0.026 0.190 0.069 0.259 0.285 4.21 MP1 1.5 86.3% 5.43 54.0% 0.7 0.003 0.030 0.002 0.032 0.557 0.265 0.822 0.854 16.29 MP2 1.9 58.5% 5.70 62.8% 0.6 0.002 0.044 0.002 0.046 0.554 0.210 0.764 0.811 11.50 MP3 1.3 83.1% 4.93 56.6% 0.1 0.031 0.048 0.056 0.104 0.499 0.490 0.990 1.093 51.52 NAN1 4.5 84.8% 3.57 48.2% 31.0 0.016 0.027 0.003 0.030 0.218 0.084 0.302 0.332 4.00 NAN2 3.4 62.8% 3.45 47.4% 31.0 0.018 0.016 0.003 0.019 0.201 0.077 0.278 0.297 5.36 NAN3 2.8 49.2% 3.72 52.4% 30.9 0.022 0.027 0.003 0.030 0.251 0.111 0.362 0.392 7.58 NAN4 3.7 84.5% 3.89 52.2% 29.8 0.015 0.027 0.002 0.029 0.203 0.070 0.273 0.283 4.15 NAN5 2.0 98.0% 3.18 44.3% 30.4 0.017 0.027 0.007 0.034 0.248 0.149 0.397 0.431 11.31 NAN6 2.2 88.7% 3.26 45.7% 30.5 0.016 0.024 0.004 0.028 0.277 0.133 0.410 0.438 10.31 NAN7 2.1 92.5% 3.60 49.8% 30.9 0.016 0.023 0.003 0.026 0.244 0.106 0.351 0.377 7.35 NAN8 2.4 100.8% 3.65 50.0% 31.1 0.018 0.031 0.002 0.033 0.204 0.076 0.280 0.313 3.93 SESA1 1.6 32.9% 4.82 56.4% 11.9 0.051 0.018 0.003 0.021 0.441 0.222 0.663 0.684 8.00 SESA2 1.4 28.6% 4.83 56.4% 11.9 0.045 0.024 0.003 0.027 0.469 0.219 0.688 0.715 7.19 SESA3 1.5 36.6% 4.83 56.2% 11.9 0.049 0.021 0.006 0.028 0.449 0.223 0.672 0.700 7.61 SESA4 1.5 38.7% 4.83 56.4% 11.9 0.046 0.024 0.003 0.027 0.470 0.221 0.691 0.718 6.73 82 WAUWINET ND ND ND ND 18.2 0.071 0.122 0.004 0.126 0.611 0.108 0.719 0.845 40.70 STREAM1 ND ND ND ND 0.3 0.077 0.081 0.021 0.102 1.419 0.258 1.677 1.779 2.64 STREAM4 ND ND ND ND <0.1 0.163 0.039 0.008 0.048 1.092 0.061 1.153 1.200 1.18 STREAM6B ND ND ND ND <0.1 0.006 0.059 0.004 0.064 1.701 0.374 2.076 2.139 16.37 STREAM6C ND ND ND ND <0.1 0.132 0.097 0.003 0.100 0.375 0.156 0.532 0.632 7.41 STREAM8 ND ND ND ND 3.3 0.015 0.045 0.005 0.050 0.398 0.118 0.516 0.565 5.29 Secchi as % of WC is the % of the water column above the secchi depth, values of 100% means that the Secchi was at or below the bottom. Lowest 20% of D.O. records for a site over the project period. HUM = Hummock Pond, Long = Long Pond, MH = Madaket Harbor, MP = Miacomet Pond, NAN = Nantucket Harbor, SESA = Sesachacha Pond 39 Figure 14. Comparison of nitrogen species (mg/L) in Nantucket Harbor in summers, 2010-2013 avg. (upper left); 2014 (upper right); 2015 (bottom) Total nitrogen is the sum of the inorganic and organic fractions (top line in each graph). All figures are to same scale. 40 Figure 14 cont'd. Comparison of nitrogen species (mg/L) in Hummock Pond in summers, 2010-2013 avg. (upper left); 2014 (upper right); 2015 (bottom). Total nitrogen is the sum of the inorganic and organic fractions (top line in each graph). All figures are to same scale. 41 Figure 14 cont'd. Comparison of nitrogen species (mg/L) in Sesachacha Pond in summers, 2010-2013 avg. (upper left); 2014 (upper right); 2015 (bottom). Total nitrogen is the sum of the inorganic and organic fractions (top line in each graph). 42 Figure 14 cont'd. Comparison of nitrogen species (mg/L) in Madaket Harbor in summers, 2010-2013 avg. (upper left); 2014 (upper right); 2015 (bottom). Total nitrogen is the sum of the inorganic and organic fractions (top line in each graph). All figures are to same scale. 43 Figure 14 cont'd. Comparison of nitrogen species (mg/L) in Long Pond (Madaket Harbor System) in summers, 2010-2013 avg. (upper left); 2014 (upper right); 2015 (bottom) Total nitrogen is the sum of the inorganic and organic fractions (top line in each graph). All figures are to same scale. 44 Figure 14 cont'd. Comparison of nitrogen species (mg/L) in Miacomet in summers, 2010-2013 avg. (upper left); 2014 (upper right); 2015 (bottom). Total nitrogen is the sum of the inorganic and organic fractions (top line in each graph). All figures are to same scale. 45 Figure 15. Estuarine water quality monitoring station locations in the Nantucket Harbor estuary system. Station labels correspond to those provided in Table 3 below. Red diamonds indicate locations of MEP monitoring stations. Blue diamonds are locations of Town sampling. Station 8 sampled in 2010, station 8N sampled in 2011 and 2012. 46 Table 3. Comparison of MEP mean TN with Town data (values mg/L) from Nantucket Harbor. MEP data collected in the summers of 1988 - 1990 and 1992 - 1994 by the Woods Hole Oceanographic Institution, and between 1992 and 2005 by the Town of Nantucket Marine Department and by the Nantucket Marine and Coastal Resources Department in summers 2010, 2012, 2013 and 2014. 2 It is almost certain that this does not represent the TN level in the inflow to Nantucket Harbor on the flood tide, but rather the 2012 data is influenced by mixing with TN enriched out-flowing waters. An attempt to control for this issue was implemented in the 2013 monitoring program. Sub-Embayment Monitoring Station Historical MEP Mean TN (mg/L) s.d. 2010 Town ID 2010 Mean TN (mg/L) 2012 Mean TN (mg/L) 2013 Mean TN (mg/L) 2014 Mean TN (mg/L) 2015 Mean TN (mg/L) Head of the Harbor - Upper 2 0.408 0.188 NA NS NS NS Head of the Harbor - Mid Town 3 0.401 0.115 3 0.392 0.411 0.415 0.345 0.436 Head of the Harbor - Lower 2A 0.339 0.070 NA NS NS NS NS NS Pocomo Head 3 0.335 0.081 NA NS NS NS NS NS Quaise Basin 3A+Town 2 0.336 0.112 2 0.297 0.364 0.345 0.314 0.374 East Polpis Harbor 4+Town 6 0.362 0.105 6 0.438 0.484 0.401 0.378 0.404 West Polpis Harbor 4A+Town 5 0.388 0.119 5 0.431 0.419 0.385 0.389 0.422 Abrams Point 5 0.335 0.060 NA NS NS NS NS NS Monomoy 6 0.297 0.086 NA NS NS NS NS NS Mooring Area 7+Town 1, 1A 0.326 0.106 1, 7 0.332, 0.377 0.335, 0.379 0.323, 0.323 0.294, 0.284 0.39, 0.33 Nantucket Sound OS+Town 4 0.239 0.041 4 0.283 0.3442 0.3171 0.277 0.297 47 Figure 16. 2005 aerial photo showing MEP monitoring station location in Sesachacha Pond that was used in the water quality analysis for the Massachusetts Estuaries Project. Station SES corresponds to SESA-1 in Tables 2a,b and Station 1 in Figure 3. 48 Sampling Station Location Historical MEP Mean TN (mg/L) s.d. 2010 Mean TN (mg/L) 2012 Mean TN (mg/L) 2013 Mean TN (mg/L) 2014 Mean TN (mg/L) 2015 Mean TN (mg/L) Sesachacha Pond 1.197 0.078 0.684 (0.704) 0.678 (0.639) 0.714 (0.669) 0.919 (0.922) 0.918 (0.904) Table 4. Comparison of MEP mean values of TN with Town TN data (all values are mg/L) from Sesachacha Pond. MEP data were collected in the summers of 1992 through 2005. Town data were collected in the summers of 2010, 2012, 2013 and 2014 by the Town of Nantucket Marine and Coastal Resources Department. Values in 2010, 2012, 2013 and 2014 represent the average at Station 1, with the average of stations 1-4 in ( ). 49 Figure 17. Estuarine water quality monitoring station locations in the Madaket Harbor and Long Pond Systems. 50 Table 5. Comparison of MEP mean values of TN with Town TN data (all values are mg/L) from Madaket Harbor and Long Pond. MEP data were collected by SMAST in the summers of 2002 through 2004. Town data were collected in the summers of 2010, 2012, 2013 and 2014 by the Town of Nantucket Marine and Coastal Resources Department. Sub-Embayment Monitoring Station Historical MEP Mean TN (mg/L) s.d. 2010 Mean TN (mg/L) 2012 Mean TN (mg/L) 2013 Mean TN (mg/L) 2014 Mean TN (mg/L) 2015 Mean TN (mg/L) Madaket Harbor MEP M1 0.336 0.098 Madaket Harbor Town 4 0.285 0.297 0.278 0.254 0.328 Madaket Harbor MEP M2 0.395 0.083 Madaket Harbor Town 2 0.436 0.444 0.323 0.347 0.418 Madaket Harbor MEP M3 0.415 0.090 Madaket Harbor Town 3 0.324 .356 0.314 0.376 0.324 Hither Creek MEP M4 0.581 0.193 Hither Creek MEP M5 0.780 0.178 Madaket Harbor MEP M6 0.347 0.067 Madaket Harbor MEP M10 0.422 0.127 Hither Creek MEP M11+Town 1 0.620 0.215 0.626 0.655 0.573 0.445 0.524 Long Pond MEP LOPO1 1.058 0.404 Long Pond MEP LOPO2+Town 5 0.971 0.369 1.385 1.013 0.709 1.481 0.697 Long Pond MEP LOPO3 0.924 0.234 Long Pond MEP LOPO4+Town 6 0.894 0.278 2.044 0.867 0.880 0.788 0.656 North Head Long P. MEP LOPO5 0.954 0.271 51 Hummock Pond and Miacomet Pond Station ID's 2015 2014 2013 2012 2010 2005/2007 TN (mg/L) TN (mg/L) TN (mg/L) TN (mg/L) TN (mg/L) TN (mg/L) Mean Mean Mean Mean Mean Mean S.D. HUM1 0.539 0.651 0.769 0.666 0.616 0.751** 0.374 HUM3 0.622 0.643 0.827 0.863 0.589 0.630** 0.388 HUM5 0.558 0.653 0.881 0.871 0.766 ND ND HUM7 0.621 0.873 1.170 1.301 1.786 1.283** 0.969 HUM8 0.576 0.755 1.064 0.944 0.983 ND ND MP1 1.297 0.864 0.792 0.828 0.854 0.842* 0.191 MP2 1.318 0.784 1.036 0.880 0.811 0.855* 0.213 MP3 0.992 1.297 1.058 0.950 1.093 0.280* 0 *2005 data only **2007 data only Table 6. Comparison of TN concentrations collected in 2005 (Miacomet Pond) and 2007 (Hummock Pond) by Nantucket Marine and Coastal Resources Department with Town TN data collected at both sites the summer of 2010, 2012, 2013, 2014 and 2015. All values are mg/L. 52 Low20%2015 Secchi Oxsat DIN TON T-Pig EUTRO Health Status EMBAYMENT SCORE SCORE SCORE SCORE SCORE Index HUM1 37.7 81.3 100.0 15.7 0.0 46.9 moderate HUM3 37.2 73.6 100.0 0.0 5.1 43.2 moderate HUM5 34.3 79.2 100.0 11.3 12.8 47.5 moderate HUM7 62.7 81.4 7.1 23.3 28.7 40.6 moderate HUM8 35.7 67.8 94.8 8.9 0.0 41.5 moderate LONG5 22.0 82.4 93.1 0.0 9.2 41.4 moderate LONG6 16.7 70.4 100.0 0.0 0.0 37.4 moderate/fair MH1 63.3 51.7 74.5 24.2 60.6 54.9 moderate MH2 81.4 72.2 52.4 61.2 98.1 73.1 High MH3 80.0 89.5 100.0 83.3 99.9 90.5 High MH4 99.0 98.5 100.0 82.2 100.0 95.9 Highe MP1 19.0 75.1 56.6 0.0 0.0 30.1 Fair-Poor MP2 17.9 79.8 42.1 0.0 0.0 28.0 Fair-Poor MP3 24.5 95.0 25.8 0.0 0.0 29.1 Fair-Poor NAN1 97.1 96.4 100.0 83.5 79.5 91.3 High NAN2 92.0 89.1 86.6 68.7 69.6 81.2 High NAN3 60.1 93.7 77.1 49.3 14.7 61.6 Moderate NAN4 100.0 94.3 100.0 97.4 85.2 95.4 High NAN5 67.6 79.2 85.7 52.2 79.2 72.8 High NAN6 74.8 84.8 97.5 56.9 68.4 76.5 High NAN7 68.7 91.8 96.4 61.7 83.1 80.4 High NAN8N 79.7 83.5 100.0 89.3 97.8 90.1 High ORS1 100.0 26.4 91.5 22.6 6.3 49.3 Moderate ORS2 48.0 49.5 85.2 83.1 86.2 70.4 High ORS3 0.0 33.8 34.6 40.4 91.0 40.0 Moderate ORS4 0.0 35.0 57.4 60.6 83.8 47.4 Moderate ORS5 21.6 56.5 99.9 35.8 100.0 62.8 High-Moderate ORS6 0.0 53.3 64.6 19.0 72.5 41.9 Moderate SESA1 25.5 88.1 100.0 0.0 0.0 42.7 Moderate SESA2 9.6 88.5 100.0 0.0 0.0 39.6 Moderate SESA3 9.6 98.4 100.0 0.0 0.0 41.6 Moderate SESA4 7.8 93.5 100.0 0.0 0.0 40.3 Moderate High Quality = >69; High-Moderate = 61-69; Moderate = 39-61; Moderate-Fair = 31-39; Fair-Poor = <31 Table 7. 2015 Trophic Health Index Scores and status for water quality monitoring stations in Nantucket estuaries based upon open water embayment (not salt marsh) habitat quality scales. Index calculated with Dissolved Oxygen data (described in Howes et. al., 1999 at www.savebuzzardsbay.org). 53 Low20%2014 Secchi Oxsat DIN TON T-Pig EUTRO Health Status EMBAYMENT SCORE SCORE SCORE SCORE SCORE Index HUM1 51.3 74.7 62.7 0.0 50.0 47.7 Moderate HUM3 34.8 78.3 68.2 0.0 53.3 46.9 Moderate HUM5 36.5 73.8 91.7 0.0 35.3 47.5 Moderate HUM7 28.1 81.0 29.3 0.0 0.0 27.7 Fair-Poor HUM8 17.1 66.6 91.7 0.0 39.2 42.9 Moderate LONG5 13.4 34.4 18.4 0.0 8.9 15.0 Fair-Poor LONG6 11.8 67.6 43.7 0.0 25.7 29.7 Fair-Poor MH1 66.1 67.6 39.4 56.9 88.8 63.7 High-Moderate MH2 88.7 65.1 72.7 82.0 100.0 81.7 High MH3 82.5 65.1 76.7 69.8 100.0 78.8 High MH4 92.6 77.8 83.8 100.0 100.0 90.8 High MP1 51.8 55.8 42.2 0.0 0.6 30.1 Moderate-Fair MP2 70.6 70.1 58.6 0.0 52.3 50.3 Moderate MP3 23.1 46.0 26.1 0.0 0.0 19.0 Fair-Poor NAN1 100.0 81.3 86.9 100.0 100.0 93.7 High NAN2 100.0 73.4 76.2 95.3 100.0 89.0 High NAN3 100.0 77.5 83.7 80.6 96.6 87.7 High NAN4 100.0 87.6 89.5 100.0 100.0 95.4 High NAN5 78.8 68.0 87.6 63.3 94.0 78.4 High NAN6 85.6 69.4 97.5 65.9 100.0 83.7 High NAN7 67.9 74.0 79.1 100.0 100.0 84.2 High NAN8N 77.6 75.7 91.2 100.0 100.0 88.9 High SESA1 41.5 75.9 54.0 0.0 28.3 39.9 Moderate SESA2 44.6 69.8 46.0 0.0 28.3 37.7 Moderate-Fair SESA3 42.5 76.8 56.0 0.0 44.5 44.0 Moderate SESA4 44.3 73.3 55.1 0.0 51.1 44.8 Moderate High Quality = >69; High-Moderate = 61-69; Moderate = 39-61; Moderate-Fair = 31-39; Fair-Poor = <31 Table 7a. 2014 Trophic Health Index Scores and status for water quality monitoring stations in Nantucket estuaries based upon open water embayment (not salt marsh) habitat quality scales. Index calculated with Dissolved Oxygen data (described in Howes et. al., 1999 at www.savebuzzardsbay.org). 54 Table 7b. 2013 Trophic Health Index Scores and status for water quality monitoring stations in Nantucket estuaries based upon open water embayment (not salt marsh) habitat quality scales. Index calculated with Dissolved Oxygen data (described in Howes et. al., 1999 at www.savebuzzardsbay.org). Low20%2013 Sta Secchi Oxsat DIN TON T-Pig EUTRO Health Status ID SCORE SCORE SCORE SCORE SCORE Index HUM-1 29.6 56.8 47.1 0.0 16.9 30.1 Fair-Poor HUM-3 30.2 42.1 18.9 0.0 26.8 23.6 Fair-Poor HUM-5 0.0 15.8 20.1 0.0 15.8 10.3 Fair-Poor HUM-7 0.8 12.2 19.8 0.0 0.0 6.6 Fair-Poor HUM-8 0.0 0.0 36.3 0.0 20.1 11.3 Fair-Poor LONG-5 11.2 77.9 81.0 0.0 17.3 37.5 Moderate-Fair LONG-6 9.3 25.0 74.8 0.0 1.1 22.0 Fair-Poor MH1 64.5 52.5 33.4 22.0 71.2 48.7 Moderate MH2 69.3 75.4 75.1 91.8 100.0 82.3 High MH3 73.6 75.4 86.5 93.0 100.0 85.7 High MH4 99.0 88.1 79.3 100.0 100.0 93.3 High MP1 31.0 62.2 83.7 0.0 0.0 35.4 Moderate-Fair MP2 41.9 30.5 44.1 0.0 0.0 23.3 Fair-Poor MP3 27.3 56.2 0.0 0.0 0.0 16.7 Fair-Poor NAN1 100.0 75.7 88.4 100.0 100.0 92.8 High NAN2 97.3 68.2 75.7 82.0 83.1 81.3 High NAN3 89.9 28.4 84.1 54.8 36.9 58.8 Moderate NAN4 100.0 88.6 81.4 93.1 100.0 92.6 High NAN5 70.7 42.6 91.3 64.3 48.0 63.4 High-Moderate NAN6 76.1 20.5 72.4 61.9 44.2 55.0 Moderate NAN7 70.0 73.8 90.9 88.6 64.4 77.5 High NAN8 78.6 72.3 64.2 100.0 100.0 83.0 High SES 1 78.9 83.6 40.3 0.0 62.4 53.0 Moderate SES 2 86.4 70.2 61.6 2.8 73.5 58.9 Moderate SES 3 88.0 77.5 52.5 0.0 80.7 59.7 Moderate SES 4 92.1 79.3 47.9 0.0 79.9 59.8 Moderate 55 Low20% Station ID Year Secchi Oxsat DIN TON T-Pig EUTRO Health Status SCORE SCORE SCORE SCORE SCORE Index HUM-1 2012 30.8 84.2 45.0 0.0 12.0 34.4 Moderate-Fair HUM-3 2012 41.0 83.4 52.8 0.0 16.0 38.6 Moderate-Fair HUM-5 2012 17.5 89.3 47.3 0.0 0.0 30.8 Fair-Poor HUM-7 2012 11.3 69.5 7.9 0.0 0.0 17.7 Fair-Poor HUM-8 2012 1.0 87.1 38.0 0.0 0.0 25.2 Fair-Poor LONG-5 2012 0.0 70.9 30.4 0.0 0.0 20.3 Fair-Poor LONG-6 2012 0.0 64.1 39.3 0.0 21.9 25.1 Fair-Poor MH1 2012 65.3 100.0 3.0 17.6 3.1 37.8 Moderate-Fair MH2 2012 83.2 100.0 20.1 68.4 100.0 74.3 High MH3 2012 84.8 100.0 27.7 99.0 100.0 82.3 High MH4 2012 100.0 100.0 53.8 100.0 100.0 90.8 High MP1 2012 55.3 84.6 36.2 0.0 0.0 35.2 Moderate-Fair MP2 2012 55.4 85.3 23.2 0.0 0.0 32.8 Moderate-Fair MP3 2012 31.0 100.0 6.7 0.0 0.0 27.5 Fair-Poor NAN1 2012 100.0 76.4 40.2 100.0 79.4 79.2 High NAN2 2012 98.9 92.6 32.5 89.4 83.0 79.3 High NAN3 2012 85.2 96.0 50.7 63.0 76.7 74.3 High NAN4 2012 98.5 99.8 57.2 88.3 84.0 85.5 High NAN5 2012 65.1 90.5 42.3 64.9 0.0 52.6 Moderate NAN6 2012 79.2 80.8 46.5 41.9 38.5 57.4 Moderate NAN7 2012 75.0 95.0 39.4 81.3 72.6 72.7 High-Moderate NAN8 2012 71.4 76.1 39.3 84.7 85.1 71.3 High SES 1 2012 84.2 80.4 43.6 0.0 45.4 50.7 Moderate SES 2 2012 88.9 80.4 14.1 17.4 55.7 51.3 Moderate SES 3 2012 95.4 80.4 36.7 17.8 71.3 60.3 Moderate SES 4 2012 93.6 80.4 30.2 0.3 66.2 54.2 Moderate High Quality = >69; High/Moderate = 61-69; Moderate = 39-61; Moderate/Fair = 31-39; Fair/Poor = <31 Table 7c. 2012 Trophic Health Index Scores and status for water quality monitoring stations in Nantucket estuaries based upon open water embayment (not salt marsh) habitat quality scales. Index calculated with Dissolved Oxygen data (described in Howes et. al., 1999 at www.savebuzzardsbay.org). 56 ID Secchi SCORE Low20% Oxsat SCORE DIN SCORE TON SCORE T-Pig SCORE EUTRO Index Health Status HUM1 54.0 41.6 100.0 4.3 2.4 40.4 Moderate HUM3 48.5 49.6 75.2 8.2 0.0 36.3 Moderate-Fair HUM5 25.9 41.7 77.7 0.0 0.0 29.0 Fair-Poor HUM7 22.4 14.5 0.4 0.0 0.0 7.4 Fair-Poor HUM8 12.2 42.6 55.2 0.0 0.0 22.0 Fair-Poor LONG5 0.6 55.8 100.0 0.0 0.0 31.3 Moderate-Fair LONG6 4.6 55.8 73.9 0.0 0.0 26.8 Fair-Poor MH1 59.0 0.3 44.5 5.4 0.0 21.8 Fair-Poor MH2 72.8 22.3 70.7 50.3 5.4 44.3 Moderate MH3 83.3 40.5 72.7 92.1 40.5 65.8 High-Moderate MH4 100.0 40.5 72.4 100.0 71.8 77.0 High MP1 54.8 37.1 63.7 0.0 0.0 31.1 Moderate-Fair MP2 70.3 55.6 47.9 0.0 0.0 34.8 Moderate-Fair MP3 47.1 42.8 12.9 0.0 0.0 20.6 Fair-Poor NAN1 100.0 23.0 66.7 90.1 76.1 71.2 High NAN2 100.0 20.9 87.2 100.0 51.8 72.0 High NAN3 95.5 33.4 66.4 66.3 23.0 56.9 Moderate NAN4 100.0 32.8 68.0 100.0 73.0 74.8 High NAN5 74.8 12.5 62.1 54.1 0.0 40.7 Moderate NAN6 81.7 16.6 69.8 49.9 0.0 43.6 Moderate NAN7 78.1 27.1 72.3 70.4 25.6 54.7 Moderate NAN8 86.7 27.5 62.3 100.0 77.6 70.8 High SESA1 62.1 42.3 82.2 0.0 18.5 41.0 Moderate SESA2 54.3 42.3 71.4 0.0 27.4 39.1 Moderate SESA3 55.9 42.0 70.2 0.0 22.7 38.2 Moderate-Fair SESA4 54.8 42.5 71.3 0.0 32.9 40.3 Moderate High Quality = >69; High/Moderate = 61-69; Moderate = 39-61; Moderate/Fair = 31-39; Fair/Poor = <31 Table 7d. 2010 Trophic Health Index Scores and status for water quality monitoring stations in Nantucket estuaries based upon open water embayment (not salt marsh) habitat quality scales. Index calculated with Dissolved Oxygen data (described in Howes et. al., 1999 at www.savebuzzardsbay.org). 57 No DO Secchi DIN TON T-Pig EUTRO Health Status EMBAYMENT SCORE SCORE SCORE SCORE Index HUM1 37.7 100.0 15.7 0.0 38.3 Moderate HUM3 37.2 100.0 0.0 5.1 35.6 Moderate-Fair HUM5 34.3 100.0 11.3 12.8 39.6 Moderate HUM7 62.7 7.1 23.3 28.7 30.4 Moderate-Fair HUM8 35.7 94.8 8.9 0.0 34.9 Moderate-Fair LONG5 22.0 93.1 0.0 9.2 31.1 Moderate-Fair LONG6 16.7 100.0 0.0 0.0 29.2 Fair-Poor MH1 63.3 74.5 24.2 60.6 55.6 Moderate MH2 81.4 52.4 61.2 98.1 73.3 High MH3 80.0 100.0 83.3 99.9 90.8 High MH4 99.0 100.0 82.2 100.0 95.3 High MP1 19.0 56.6 0.0 0.0 18.9 Fair-Poor MP2 17.9 42.1 0.0 0.0 15.0 Fair-Poor MP3 24.5 25.8 0.0 0.0 12.6 Fair-Poor NAN1 97.1 100.0 83.5 79.5 90.0 High NAN2 92.0 86.6 68.7 69.6 79.2 High NAN3 60.1 77.1 49.3 14.7 50.3 Moderate NAN4 100.0 100.0 97.4 85.2 95.6 High NAN5 67.6 85.7 52.2 79.2 71.2 High NAN6 74.8 97.5 56.9 68.4 74.4 High NAN7 68.7 96.4 61.7 83.1 77.5 High NAN8N 79.7 100.0 89.3 97.8 91.7 High ORS1 100.0 91.5 22.6 6.3 55.1 Moderate ORS2 48.0 85.2 83.1 86.2 75.6 High ORS3 0.0 34.6 40.4 91.0 41.5 Moderate ORS4 0.0 57.4 60.6 83.8 50.4 Moderate ORS5 21.6 99.9 35.8 100.0 64.3 High-Moderate ORS6 0.0 64.6 19.0 72.5 39.0 Moderate SESA1 25.5 100.0 0.0 0.0 31.4 Moderate-Fair SESA2 9.6 100.0 0.0 0.0 27.4 Fair-Poor SESA3 9.6 100.0 0.0 0.0 27.4 Fair-Poor SESA4 7.8 100.0 0.0 0.0 26.9 Fair-Poor High Quality = >69; High-Moderate = 61-69; Moderate = 39-61; Moderate-Fair = 31-39; Fair-Poor = <31 Table 8. 2015 Trophic Health Index Scores and status for water quality monitoring stations in Nantucket estuaries based upon open water embayment (not salt marsh) habitat quality scales. Index calculated without Dissolved Oxygen data (described in Howes et. al., 1999 at www.savebuzzardsbay.org). 58 No DO Secchi DIN TON T-Pig EUTRO Health Status EMBAYMENT SCORE SCORE SCORE SCORE Index HUM1 51.3 62.7 0.0 50.0 41.0 Moderate HUM3 34.8 68.2 0.0 53.3 39.1 Moderate HUM5 36.5 91.7 0.0 35.3 40.9 Moderate HUM7 28.1 29.3 0.0 0.0 14.3 Fair-Poor HUM8 17.1 91.7 0.0 39.2 37.0 Moderate-Fair LONG5 13.4 18.4 0.0 8.9 10.2 Fair-Poor LONG6 11.8 43.7 0.0 25.7 20.3 Fair-Poor MH1 66.1 39.4 56.9 88.8 62.8 High-Moderate MH2 88.7 72.7 82.0 100.0 85.8 High MH3 82.5 76.7 69.8 100.0 82.2 High MH4 92.6 83.8 100.0 100.0 94.1 High MP1 51.8 42.2 0.0 0.6 23.6 Fair-Poor MP2 70.6 58.6 0.0 52.3 45.4 Moderate MP3 23.1 26.1 0.0 0.0 12.3 Fair-Poor NAN1 100.0 86.9 100.0 100.0 96.7 High NAN2 100.0 76.2 95.3 100.0 92.9 High NAN3 100.0 83.7 80.6 96.6 90.2 High NAN4 100.0 89.5 100.0 100.0 97.4 High NAN5 78.8 87.6 63.3 94.0 80.9 High NAN6 85.6 97.5 65.9 100.0 87.3 High NAN7 67.9 79.1 100.0 100.0 86.8 High NAN8N 77.6 91.2 100.0 100.0 92.2 High SESA1 41.5 54.0 0.0 28.3 30.9 Moderate-Fair SESA2 44.6 46.0 0.0 28.3 29.7 Fair-Poor SESA3 42.5 56.0 0.0 44.5 35.8 Moderate-Fair SESA4 44.3 55.1 0.0 51.1 37.6 Moderate-Fair High Quality = >69; High-Moderate = 61-69; Moderate = 39-61; Moderate-Fair = 31-39; Fair-Poor = <31 Table 8a. 2014 Trophic Health Index Scores and status for water quality monitoring stations in Nantucket estuaries based upon open water embayment (not salt marsh) habitat quality scales. Index calculated without Dissolved Oxygen data (described in Howes et. al., 1999 at www.savebuzzardsbay.org). 59 Table 8b. 2013 Trophic Health Index Scores and status for water quality monitoring stations in Nantucket estuaries based upon open water embayment (not salt marsh) habitat quality scales. Index calculated without Dissolved Oxygen data (described in Howes et. al., 1999 at www.savebuzzardsbay.org). No DO Sta Secchi DIN TON T-Pig EUTRO Health Status ID SCORE SCORE SCORE SCORE Index HUM-1 29.6 47.1 0.0 16.9 23.4 Fair-Poor HUM-3 30.2 18.9 0.0 26.8 19.0 Fair-Poor HUM-5 0.0 20.1 0.0 15.8 9.0 Fair-Poor HUM-7 0.8 19.8 0.0 0.0 5.2 Fair-Poor HUM-8 0.0 36.3 0.0 20.1 14.1 Fair-Poor LONG-5 11.2 81.0 0.0 17.3 27.4 Fair-Poor LONG-6 9.3 74.8 0.0 1.1 21.3 Fair-Poor MH1 64.5 33.4 22.0 71.2 47.8 Moderate MH2 69.3 75.1 91.8 100.0 84.0 High MH3 73.6 86.5 93.0 100.0 88.3 High MH4 99.0 79.3 100.0 100.0 94.6 High MP1 31.0 83.7 0.0 0.0 28.7 Fair-Poor MP2 41.9 44.1 0.0 0.0 21.5 Fair-Poor MP3 27.3 0.0 0.0 0.0 6.8 Fair-Poor NAN1 100.0 88.4 100.0 100.0 97.1 High NAN2 97.3 75.7 82.0 83.1 84.5 High NAN3 89.9 84.1 54.8 36.9 66.4 High-Moderate NAN4 100.0 81.4 93.1 100.0 93.6 High NAN5 70.7 91.3 64.3 48.0 68.6 High-Moderate NAN6 76.1 72.4 61.9 44.2 63.6 High-Moderate NAN7 70.0 90.9 88.6 64.4 78.4 High NAN8 78.6 64.2 100.0 100.0 85.7 High SES 1 78.9 40.3 0.0 62.4 45.4 Moderate SES 2 86.4 61.6 2.8 73.5 56.1 Moderate SES 3 88.0 52.5 0.0 80.7 55.3 Moderate SES 4 92.1 47.9 0.0 79.9 55.0 Moderate 60 Station ID Year Secchi DIN TON T-Pig EUTRO Health Status SCORE SCORE SCORE SCORE Index HUM-1 2012 30.8 45.0 0.0 12.0 22.0 Fair-Poor HUM-3 2012 41.0 52.8 0.0 16.0 27.4 Fair-Poor HUM-5 2012 17.5 47.3 0.0 0.0 16.2 Fair-Poor HUM-7 2012 11.3 7.9 0.0 0.0 4.8 Fair-Poor HUM-8 2012 1.0 38.0 0.0 0.0 9.7 Fair-Poor LONG-5 2012 0.0 30.4 0.0 0.0 7.6 Fair-Poor LONG-6 2012 0.0 39.3 0.0 21.9 15.3 Fair-Poor MH1 2012 65.3 3.0 17.6 3.1 22.3 Fair-Poor MH2 2012 83.2 20.1 68.4 100.0 67.9 High-Moderate MH3 2012 84.8 27.7 99.0 100.0 77.9 High MH4 2012 100.0 53.8 100.0 100.0 88.4 High MP1 2012 55.3 36.2 0.0 0.0 22.9 Fair-Poor MP2 2012 55.4 23.2 0.0 0.0 19.7 Fair-Poor MP3 2012 31.0 6.7 0.0 0.0 9.4 Fair-Poor NAN1 2012 100.0 40.2 100.0 79.4 79.9 High NAN2 2012 98.9 32.5 89.4 83.0 76.0 High NAN3 2012 85.2 50.7 63.0 76.7 68.9 High-Moderate NAN4 2012 98.5 57.2 88.3 84.0 82.0 High NAN5 2012 65.1 42.3 64.9 0.0 43.1 Moderate NAN6 2012 79.2 46.5 41.9 38.5 51.5 Moderate NAN7 2012 75.0 39.4 81.3 72.6 67.1 High-Moderate NAN8 2012 71.4 39.3 84.7 85.1 70.1 High SES 1 2012 84.2 43.6 0.0 45.4 43.3 Moderate SES 2 2012 88.9 14.1 17.4 55.7 44.1 Moderate SES 3 2012 95.4 36.7 17.8 71.3 55.3 Moderate SES 4 2012 93.6 30.2 0.3 66.2 47.6 Moderate High Quality = >69; High/Moderate = 61-69; Moderate = 39-61; Moderate/Fair = 31-39; Fair/Poor = <31 Table 8c. 2012 Trophic Health Index Scores and status for water quality monitoring stations in Nantucket estuaries based upon open water embayment (not salt marsh) habitat quality scales. Index calculated without Dissolved Oxygen data (described in Howes et. al., 1999 at www.savebuzzardsbay.org). 61 ID Secchi SCORE DIN SCORE TON SCORE T-Pig SCORE EUTRO Index Health Status HUM1 54.0 100.0 4.3 2.4 40.1 Moderate HUM3 48.5 75.2 8.2 0.0 33.0 Moderate-Fair HUM5 25.9 77.7 0.0 0.0 25.9 Fair-Poor HUM7 22.4 0.4 0.0 0.0 5.7 Fair-Poor HUM8 12.2 55.2 0.0 0.0 16.9 Fair-Poor LONG5 0.6 100.0 0.0 0.0 25.2 Fair-Poor LONG6 4.6 73.9 0.0 0.0 19.6 Fair-Poor MH1 59.0 44.5 5.4 0.0 27.2 Fair-Poor MH2 72.8 70.7 50.3 5.4 49.8 Moderate MH3 83.3 72.7 92.1 40.5 72.1 High MH4 100.0 72.4 100.0 71.8 86.1 High MP1 54.8 63.7 0.0 0.0 29.6 Fair-Poor MP2 70.3 47.9 0.0 0.0 29.6 Fair-Poor MP3 47.1 12.9 0.0 0.0 15.0 Fair-Poor NAN1 100.0 66.7 90.1 76.1 83.3 High NAN2 100.0 87.2 100.0 51.8 84.7 High NAN3 95.5 66.4 66.3 23.0 62.8 High-Moderate NAN4 100.0 68.0 100.0 73.0 85.3 High NAN5 74.8 62.1 54.1 0.0 47.8 Moderate NAN6 81.7 69.8 49.9 0.0 50.4 Moderate NAN7 78.1 72.3 70.4 25.6 61.6 High-Moderate NAN8 86.7 62.3 100.0 77.6 81.7 High SESA1 62.1 82.2 0.0 18.5 40.7 Moderate SESA2 54.3 71.4 0.0 27.4 38.3 Moderate-Fair SESA3 55.9 70.2 0.0 22.7 37.2 Moderate-Fair SESA4 54.8 71.3 0.0 32.9 39.8 Moderate High Quality = >69; High/Moderate = 61-69; Moderate = 39-61; Moderate/Fair = 31-39; Fair/Poor = <31 Table 8d. 2010 Trophic Health Index Scores and status for water quality monitoring stations in Nantucket estuaries based upon open water embayment (not salt marsh) habitat quality scales. Index calculated without Dissolved Oxygen data (described in Howes et. al., 1999 at www.savebuzzardsbay.org). 62 Figure 18. Madaket Harbor Eutrophication Index 2010 (top triangle) and 2015 (bottom triangle). Index was calculated with dissolved oxygen. Colors indicate High (Blue), Moderate (Yellow), Fair/Poor (Red) nutrient related water quality. 63 Figure 19. Nantucket Harbor Eutrophication Index 2010 (top triangle) and 2015 (bottom triangle). Index was calculated with dissolved oxygen. Colors indicate High (Blue), Moderate (Yellow), Fair/Poor (Red) nutrient related water quality. 64 Figure 20. Sesachacha Pond Eutrophication Index 2010 (top triangle) and 2015 (bottom triangle). Index was calculated with dissolved oxygen. Colors indicate High (Blue), Moderate (Yellow), Fair/Poor (Red) nutrient related water quality. 65 Figure 21. Hummock Pond Eutrophication Index 2010 (top triangle) and 2015 (bottom triangle). Index was calculated with dissolved oxygen. Colors indicate High (Blue), Moderate (Yellow), Fair/Poor (Red) nutrient related water quality. 66 Figure 22. Miacomet Pond Eutrophication Index 2010 (top triangle) and 2015 (bottom triangle). Index was calculated with dissolved oxygen. Colors indicate High (Blue), Moderate (Yellow), Fair/Poor (Red) nutrient related water quality.