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The regional effects of both nutrient loading and bacterial contamination span the <br /> spectrum from environmental to socio-economic impacts and have direct consequences to the <br /> culture, economy, and tax base of Massachusetts's coastal communities. The primary nutrient <br /> causing the increasing impairment of our coastal embayments is nitrogen, with its primary <br /> sources being wastewater disposal, and nonpoint source runoff that carries nitrogen (e.g. <br /> fertilizers) from a range of other sources. Nitrogen related water quality decline represents one <br /> of the most serious threats to the ecological health of the nearshore coastal waters. Coastal . <br /> embayments, because of their shallow nature and large shoreline area, are generally the first <br /> coastal systems to show the effect of nutrient pollution from terrestrial sources. <br /> In particular, the Waquoit Bay embayment system within the Towns of Falmouth and <br /> Mashpee is showing signs of eutrophication (over enrichment) from enhanced nitrogen loads <br /> entering through groundwater from the increasingly developed watershed to this coastal system. <br /> Eutrophication is a process that occurs naturally and gradually over a period of tens or hundreds <br /> of years. However, human-related (anthropogenic) sources of nitrogen may be introduced into <br /> ecosystems at an accelerated rate that cannot be easily absorbed, resulting in a phenomenon <br /> known as cultural eutrophication. In both marine and freshwater systems, cultural <br /> eutrophication results in degraded water quality, adverse impacts to ecosystems, and limits on <br /> the use of water resources. <br /> The Towns of Falmouth and Mashpee have recognized the severity of the problem of <br /> eutrophication and the need for watershed nutrient management. The Town of Falmouth is <br /> currently developing a Comprehensive Wastewater Management Plan which the Town plans to <br /> implement upon its completion. The Town of Falmouth has also been working with the Town of <br /> Mashpee that has also completed and implemented wastewater planning in the portions of <br /> Waquoit Bay watershed that exist within the Town of Mashpee. In this manner, this analysis of <br /> the Waquoit Bay system is yielding results which can be utilized by the Town of Falmouth along <br /> with MEP results developed for the other estuaries of the town (specifically, Rands Harbor, <br /> Fiddlers Cove, Wild Harbor, West Falmouth Harbor, Quissett Harbor, Little Pond, Falmouth <br /> Inner Harbor, Oyster Pond, Great Pond, Green Pond, Bournes Pond and Eel Pond/Childs River) <br /> in order to give the Towns of Falmouth and Mashpee the necessary results to plan out and <br /> implement a unified town-wide approach to nutrient management. The Towns of Falmouth and <br /> Mashpee with associated working groups have recognized that a rigorous scientific approach <br /> yielding site-specific nitrogen loading targets was required for decision-making and alternatives' <br /> analysis. The completion of this multi-step process has taken place under the programmatic <br /> umbrella of the Massachusetts Estuaries Project, which is a partnership effort between all MEP <br /> collaborators and the Towns. The modeling tools developed as part of this program provide the <br /> quantitative information necessary for the Towns' nutrient management groups to predict the <br /> impacts on water quality from a variety of proposed management scenarios. <br /> Nitrogen Loading Thresholds and Watershed Nitrogen Management: Realizing the <br /> need for scientifically defensible management tools has resulted in a focus on determining the <br /> aquatic system's assimilative capacity for nitrogen. The highest-level approach is to directly link <br /> the watershed nitrogen inputs with embayment hydrodynamics to produce water quality results <br /> that can be validated by water quality monitoring programs. This approach when linked to state- <br /> of-the-art habitat assessments yields accurate determination of the "allowable N concentration <br /> increase" or "threshold nitrogen concentration". These determined nitrogen concentrations are <br /> then directly relatable to the watershed nitrogen loading, which also accounts for the spatial <br /> distribution of the nitrogen sources, not just the total load. As such, changes.in nitrogen load <br /> from differing parts of the embayment watershed can be evaluated relative to the degree to <br /> which those load changes drive embayment water column nitrogen concentrations toward the <br /> Executive Summary 2 <br />