Estuary Delineation and Assessment

MassBays is a large and complex system. A detailed characterization of the nearshore estuarine system highlights primary resources that need to be protected and issues to be addressed in order to improve estuarine conditions.

MassBays works primarily in the near-shore, estuarine systems of the region, in light of the strong leadership of Massachusetts’ watershed associations, and the significant and effective investment the Commonwealth has made in ocean planning. To support this work and as an alternative to a coastal delineation that uses municipal boundaries, MassBays uses ecosystem-based landward and seaward boundaries to define the MassBays planning area. Using these boundaries and geospatially available data, a glimpse into the relative ecological condition of estuaries within Massachusetts and Cape Cod Bays was assessed. 

Estuary Delineation and Assessment

The Estuary Delineation and Assessment Report (EDA) characterizes 68 assessment areas in the coastal zone of Ipswich Bay, Massachusetts Bay and Cape Cod Bay. Broadly, the assessment areas include estuarine embayments, rocky shorelines, and beaches. Characterization is based on attributes that include tidal flats, shorebird habitat and nesting sites, anadromous fish runs, salt marsh, eelgrass beds, shellfish habitat, impervious area, stormwater and waste water discharge, land use change, population density, water quality conditions, fish barriers, designated shellfish growing area classification, and stream crossings.


Specific datasets are used to categorize embayments by type and to establish target conditions. EDA 2.0 will serve as a tool to track changes in estuarine conditions over time (Section 320 of the Clean Water Act). MassBays continues to work with U.S. EPA's Office of Research and Development to develop a framework that will be used to track improvement in water quality and habitat conditions in the estuaries in line with the goals of MassBays' Comprehensive Conservation and Management Plan.

The report is available below: 2017 Estuary Delineation and Assessment 2.0. Geosyntec Consultants and MassBays National Estuary Program. August 2017

Hard copies of the report and maps are available upon request to:

Additional Resources for

Estuary Delineation and Assessment Viewer

The EDA 2.0 results will be available shortly as a set of interactive maps that document resources and stressors in each of the embayments.