Watershed Definition and Study Area

Jurisdictional Interests of the Buzzards Bay NEP

This page was created to define the programmatic and jurisdictional interests of the Buzzards Bay National Estuary Program.

When the Buzzards Bay NEP joined the National Estuary Program in 1987, its interests were identified as protecting and restoring water quality and living resources of Buzzards Bay, and managing pollution inputs and human perturbations in the surrounding watershed. In 1989, the NEP worked with USGS, the Cape Cod Commission, and area scientists to define a true hydraulic watershed of Buzzards Bay, including relevant portions of Cape Cod. This watershed definition was codified and adopted by both the Commonwealth of Massachusetts and the US Environmental Protection Agency in the 1992 Comprehensive Conservation and Management Plan (CCMP) for Buzzards Bay. This adopted watershed boundary was principally based on groundwater elevations in Carver, Plymouth, Bourne, and Falmouth (glacial outwash and moraine areas), and land surface topography in the rest of the watershed (mostly bedrock defined aquifers).

Buzzards Bay Study Area

In 2009, as part of the update of the new Buzzards Bay CCMP, the Buzzards Bay NEP adopted a slightly revised “Study Area” definition (jurisdictional interests of the program) shown in the figure to the right. Specifically, the watershed northern and Cape Cod boundaries were made consistent with new groundwater divide information from USGS defining the groundwater contribution area in the Plymouth-Carver, Cape Cod, and other southeastern Massachusetts aquifers. The USGS report summarizing their findings can be found in USGS Circular 1338. The supporting GIS coverage supporting this study is available at: water.usgs.gov/GIS/metadata/usgswrd/XML/ds451_gwcontrib_areas.xml. The USGS data set was smoothed to 100 m intervals and was intersected with earlier Buzzards Bay watershed coverages. Other details about the changing Buzzards Bay watershed definition is available at on our Buzzards Bay Boundary page.

The NEP study area totals 684 square miles (=438,142 acres or 1,773 square kilometers). This study area consists of 434 square miles of land (=277,606 acres or 1,123 square kilometers; includes land in both Massachusetts and Rhode Island [6.8 sq miles], freshwater pond area not broken out) and 250 square miles of water in Massachusetts (160,536 acres or 650 sq. kilometers; includes a small portion of areas on nautical charts sometimes labeled Rhode Island Sound in Massachusetts waters). This coverage builds upon earlier coverages.

2009 Buzzards Bay study areaBuzzards Bay Study Area
Click to enlarge

Download the zipped GIS data shapefile:


Jurisdictional and Geographic Policies of the BBNEP



For Buzzards Bay NEP municipal grants derived from Section 320 (National Estuary Program) federal funds, projects must be located wholly or principally in the Buzzards Bay watershed. For projects with multiple sites, preference will be given to those sites within the watershed, but companion sites outside the watershed will be considered if it is intrinsic to the success of the project as a whole. Projects that have town-wide benefits (e.g. recycling programs) will be considered if the benefits within the Buzzards Bay watershed are demonstrable. Funding awarded from non-section 320 funds may be spent outside the watershed boundary as allowed, required, or defined by the funding source.

Technical Assistance

Technical assistance will be provided to the Buzzards Bay watershed municipalities to the maximum extent feasible. For town’s that straddle the Buzzards Bay watershed, the Buzzards Bay NEP will assist on projects outside the watershed if they have town-wide or bay-wide benefits (e.g. policy or regulatory implications throughout the town or watershed). The Buzzards Bay NEP from time to time also provides technical assistance to other Massachusetts municipalities outside the watershed in the spirit or technology and information transfer, as required by state or federal grants, and subject to staff availability.

When the Buzzards Bay NEPs began implementing the Buzzards Bay CCMP by providing grants and technical assistance, the Buzzards Bay NEP adopted this watershed boundary as the principal jurisdictional interest of the program for the purpose of providing grants and technical assistance (see box to the right).

Other Information

Since that watershed boundary was adopted in 1991, the Buzzards Bay NEP has used new scientific information about groundwater movement to refine the watershed boundary to ensure it matches the best available scientific information. The Buzzards Bay NEP is currently reviewing the southern bay boundary in its relation to the Massachusetts Ocean Plan boundary, and new Coast Guard and Massachusetts legislature designations defining the boundaries of Buzzards Bay. Specifically, in 2004, the Massachusetts Legislature defined Buzzards Bay as “the waterway bounded and described as follows: from Sakonnet point southward to the north end of the Buzzards bay traffic separation zone, to the southwestern tip of Cuttyhunk Island thence through Buzzards bay to the eastern entrance of the Cape Cod canal at the United States Coast Guard “CC” Buoy in Cape Cod Bay, including Woods Hole Passage and Quicks Hole.)

In 2007, the USCG, faced with new pilotage requirements for the transport of oil in Buzzards Bay created a new definition of the waters of Buzzards Bay for the purpose of those regulations. Specifically, Buzzards Bay is “the body of water east and north of a line drawn from the southern tangent of Sakonnet Point, Rhode Island, in approximate position latitude 41°-27.2′ North, longitude 70°-11.7′ West, to the Buzzards Bay Entrance Light in approximate position latitude 41°-23.5′ North, longitude 71°-02.0′ West, and then to the southwestern tangent of Cuttyhunk Island, Massachusetts, at approximate position latitude 41°-24.6′ North, longitude 70°-57.0′ West, and including all of the Cape Cod Canal to its eastern entrance, except that the area of New Bedford harbor within the confines (north) of the hurricane barrier, and the passages through the Elizabeth Islands, is not considered to be ‘Buzzards Bay’.”

Defining the entrance of Buzzards Bay has been a complicated issue. This is because unlike political boundaries, there has not been any formal definition of where Buzzards Bay begins (and where Rhode Island Sound ends) on nautical charts. The BBNEP sought to address this point in this July 2000 correspondence to the WRWA on the definition of the boundary of Buzzards Bay and its watershed (700 kb pdf file, graphics degraded to allow smaller file size).

See also our page describing the changes in the Buzzards Bay watershed definition over the years.