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"threshold" for the embayment system. To increase certainty, the "Linked" Model is <br /> independently calibrated and validated for each embayment <br /> Massachusetts Estuaries Project Approach: The Massachusetts Department of <br /> Environmental Protection (DEP), the University of Massachusetts— Dartmouth School of Marine <br /> Science and Technology (SMAST), and others including the Cape Cod Commission (CCC) <br /> have undertaken the task of providing a quantitative tool to communities throughout <br /> southeastern Massachusetts (the Linked Watershed-Embayment Management Model) for <br /> nutrient management in their coastal embayment systems. Ultimately, use of the Linked <br /> Watershed-Embayment Management Model tool by municipalities in the region results in <br /> effective screening of nitrogen reduction approaches and eventual restoration and protection of <br /> valuable coastal resources. The MEP provides technical guidance in support of policies on <br /> nitrogen loading to embayments, wastewater management decisions, and establishment of <br /> nitrogen Total Maximum Daily Loads (TMDLs). A TMDL represents the greatest amount of a <br /> pollutant that a waterbody can accept and still meet water quality standards for protecting public <br /> health and maintaining the designated beneficial uses of those waters for drinking, swimming, <br /> recreation and fishing. The MEP modeling approach assesses available options for meeting <br /> selected nitrogen goals that are protective of embayment health and achieve water quality <br /> standards. <br /> The core of the Massachusetts Estuaries Project analytical method is the Linked <br /> Watershed-Embayment Management Modeling Approach, which links watershed inputs with <br /> embayment circulation and nitrogen characteristics. <br /> The Linked Model builds on well-accepted basic watershed nitrogen loading approaches <br /> such as those used in the Buzzards Bay Project, the CCC models, and other relevant models. <br /> However, the Linked Model differs from other nitrogen management models in that it: <br /> • requires site-specific measurements within each watershed and embayment; <br /> • uses realistic "best-estimates" of nitrogen loads from each land-use (as opposed to loads <br /> with built-in "safety factors" like Title 5 design loads); <br /> • spatially distributes the watershed nitrogen loading to the embayment; <br /> • accounts for nitrogen attenuation during transport to the embayment; <br /> • includes a 2D or 3D embayment circulation model depending on embayment structure; <br /> • accounts for basin structure, tidal variations, and dispersion within the embayment; <br /> • includes nitrogen regenerated within the embayment; <br /> • is validated by both independent hydrodynamic, nitrogen concentration, and ecological data; <br /> • is calibrated and validated with field data prior to generation of"what if'scenarios. <br /> The Linked Model Approach's greatest assets are its ability to be clearly calibrated and <br /> validated, and its utility as a management tool for testing 'what if' scenarios for evaluating <br /> watershed nitrogen management options. <br /> For a comprehensive description of the Linked Model, please refer to the Full Report - <br /> Nitrogen Modeling to Support Watershed Management: Comparison of Approaches and <br /> Sensitivity Analysis, available for download at http://www.state.ma.us/dep/smerp/smerp.htm. A <br /> more basic discussion of the Linked Model is also provided in Appendix F of the Massachusetts <br /> Estuaries Project Embayment Restoration Guidance for Implementation Strategies, available for <br /> download at http://www.state.ma.us/dep/smerp/smerp.htm. The Linked Model suggests which <br /> management solutions will adequately protect or restore embayment water quality by enabling <br /> Executive Summary 3 <br />