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Coastal Resource Guide Pleasant Bay and ... - Town to Chatham

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<strong>Coastal</strong> <strong>Resource</strong> <strong>Guide</strong> for <strong>Pleasant</strong> <strong>Bay</strong> <strong>and</strong> <strong>Chatham</strong> HarborThe approximately 300 acres of Saline/Brackish Flats in the centralpart of <strong>Pleasant</strong> <strong>Bay</strong> is the only priority natural community typeidentified by NHESP in the study area (Map 14). This prioritycommunity type, located between Sipson Isl<strong>and</strong> <strong>and</strong> Strong Isl<strong>and</strong>,has a community state rank of S3. 5 The Saline/Brackish Flatsestuarine community type is a sparsely vegetated intertidal habitatfound on mineral substrates. The flats are characterized by theNHESP as having an excellent diversity of marine fauna <strong>and</strong> algaein a variety of microhabitats. Horseshoe crabs are abundant hereas are shorebirds during migration. As mentioned in Section 7.4.3(Freshwater Wetl<strong>and</strong>s), exemplary occurrences of the state <strong>and</strong>globally rare New Engl<strong>and</strong> <strong>Coastal</strong> Plain Pond Shore Community(S2) <strong>and</strong> the Atlantic White Cedar Swamp Community (S2) havebeen documented among the freshwater ponds within the ACEC. 67.6 Water QualityThe <strong>Pleasant</strong> <strong>Bay</strong> Citizen Water Quality Moni<strong>to</strong>ring Program hasbeen moni<strong>to</strong>ring water quality in the <strong>Bay</strong> since 2000 in order <strong>to</strong>obtain consistent <strong>and</strong> comprehensive data <strong>to</strong> gauge nutrient inputsfrom the watershed <strong>and</strong> other sources. Twenty stations weremoni<strong>to</strong>red in 2011, <strong>and</strong> the program will moni<strong>to</strong>r that number forthe foreseeable future. The water quality data collected is essentialfor trend analyses <strong>and</strong> is relied upon by the <strong>to</strong>wns for development<strong>and</strong> compliance moni<strong>to</strong>ring for wastewater management plans.declining at others (Table 4). However, most of the sites do notdemonstrate any statistically significant trends. Sites showingimprovement in water quality are typically located in open waterareas of the <strong>Bay</strong>, while sites showing declining water qualitytend <strong>to</strong> be located in the sub-embayments. Results of the baywideanalysis indicate that water quality was declining for someparameters prior <strong>to</strong> the 2007 break in Nauset Beach, but that ithas been improving for these same parameters since that time.Other parameters remain unchanged. The results suggest that theincreased exchange of water between the <strong>Bay</strong> <strong>and</strong> ocean (due <strong>to</strong>2007 inlet formation) may be responsible for limited improvementsin water quality in some open areas of the <strong>Bay</strong>. Even with limitedimprovement in these areas, bioactive nitrogen concentrationscontinue <strong>to</strong> exceed MEP-modeled res<strong>to</strong>ration values for estuarinehealth. Furthermore, the anticipated continued southern migrationof the 2007 inlet suggests that tidal flushing <strong>and</strong> nitrogenconcentrations in the <strong>Bay</strong> may, over time, return <strong>to</strong> pre-inletconditions.The Massachusetts Estuaries Project (MEP) used water qualitydata collected by the <strong>Pleasant</strong> <strong>Bay</strong> program <strong>to</strong> determine criticalnitrogen loading thresholds. The MEP determined that in order<strong>to</strong> remain healthy enough <strong>to</strong> sustain eelgrass, waters in <strong>Pleasant</strong><strong>Bay</strong> would have a concentration of bioactive nitrogen not <strong>to</strong>exceed 0.21 mg/l (Howes et al, 2006). In 2007, the MassachusettsDepartment of Environmental Protection established TMDL’s (<strong>to</strong>talmaximum daily loads) for <strong>to</strong>tal nitrogen the <strong>Bay</strong>. The TMDLsrepresent the amount of nitrogen the <strong>Bay</strong> can receive <strong>and</strong> notexceed the threshold bioactive nitrogen concentration identified bythe MEP (Massachusetts EOEA, 2007). A TMDL for <strong>to</strong>tal nitrogenwas calculated for each of <strong>Pleasant</strong> <strong>Bay</strong>’s nineteen subembayments.The TMDL’s, which range from 2 <strong>to</strong> 155 kg/day, require reductionsin current watershed nitrogen loads of up <strong>to</strong> 100% in certainsubwatersheds. Because septic systems account for three quartersof the controllable watershed nitrogen load, several <strong>to</strong>wns arepursuing comprehensive wastewater treatment <strong>to</strong> achieve targetednitrogen reductions. Other nitrogen reduction strategies, such asminimizing loadings from s<strong>to</strong>rmwater runoff <strong>and</strong> fertilizer use, alsoare being explored but alone are not sufficient <strong>to</strong> achieve targetednitrogen reductions.In an effort <strong>to</strong> better underst<strong>and</strong> water quality trends in <strong>Pleasant</strong><strong>Bay</strong>, statistical analysis was conducted on the 10 years of waterquality data that have been collected (Cadmus, 2010). Statisticalanalysis of the data included a bay-wide trend analysis, as well assite-specific analyses. Analysis of the data also identify any effectsof the new inlet (2007), with its concomitant increase in the rate<strong>and</strong> volume of water exchange between <strong>Pleasant</strong> <strong>Bay</strong> <strong>and</strong> theAtlantic Ocean, on trends in bay water quality.The results of the site-specific analysis of water quality trendsdemonstrate that water quality is improving at some sites, but30<strong>Pleasant</strong> <strong>Bay</strong> Alliance 2011

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