On March 1, 2005, DEP published the Massachusetts Mouth of Coastal River Maps. These maps identify the Mouth Of The River (MOR) for coastal rivers in order to provide a clear, consistent, and predictable means of locating all river mouths in the Commonwealth. The MOR lines represent the limit of Riverfront Area jurisdiction under the Wetlands Protection Act. Land upstream of the MOR lines includes Riverfront Areas subject to the protections afforded by the wetlands regulations; any land seaward of the MOR line is not subject to jurisdiction as a Riverfront Area but remains subject to other inland and coastal provisions of the Wetland Protection Act.

These maps, dated March 1, 2005, represent the final MOR maps for each community. Each community received a set of maps corresponding to the rivers in their community. The final maps are a culmination of a year's effort that included distribution of draft maps for public comment, receipt and review of over 100 written comments, and field surveys for many of the more difficult mouth of river lines.

By adopting a uniform approach to mapping river mouths, these maps should reduce the need for individual MOR delineations and in turn provide a predictable means for project review for landowners, conservation commissions and MassDEP. Designations of perennial streams on the United States Geological Survey quadrangle maps served as the basis for the initial identification of all rivers in Massachusetts. In addition, one or more of the following criteria were used by MassDEP to determined the final Mouth of Coastal River maps:

  • End of parallel banks; point at which bank to bank river mouth line loses approximate "perpendicular" nature;
  • Visual characteristics of apparent sub-marine channel on orthophoto maps;
  • Identifiable landward edge of Bank interface with Coastal Beach or Vegetated Dune;
  • Seaward edge of Salt Marsh;
  • Inland of named features shown on the most current USGS map including coves, harbors, bays, embayments, salt ponds (including those with CZM salt pond designation), sounds, as well as "Guts" and "straights" that connect ocean feature to ocean feature;
  • Downstream side of control structure designed as barrier to coastal flooding (e.g. dike, tide gate, or solid fill causeway).

These maps only apply to coastal communities on the north and south shores.


Mouth-of-River Maps by Coastal Region:

Buzzards Bay

Cape Cod


North Coast

South Coast