Mousam River

Watershed Description

The Mousam River Watershed drains portions of Acton, Shapleigh, Waterboro, Sanford, Alfred, Lyman, and Kennebunk, Maine. The western portion of the watershed is largely rural, with thousands of acres of wetlands, forests, and agricultural lands. Development near the headwaters of the Mousam River is concentrated along the shores of the lakes and ponds and the densest development occurs around the river as it passes through the center of Sanford. In this area, an extremely high percentage of impervious surface causes increased flows of stormwater to the river. In the eastern region of the watershed, Middle Branch is surrounded by agricultural and forested lands as well, with dense development occurring near the town centers of Waterboro and Alfred.

Several parcels of conservation land are located throughout the watershed, particularly in the lower portion, including state and federally managed lands as wells as privately held easements. The extensive wetlands and forested lands in the upper portions of the watershed consist of scattered areas of significant habitat for a variety of wildlife, including waterfowl and wading birds, the endangered northern black racer, the ringed boghunter,  the endangered Blanding's turtle, and the endangered spotted turtle. The river passes through an extensive tidal estuary area as it reaches the Atlantic, which functions as important habitat for shorebirds and the endangered Piping Plover.

Due to the extensive undeveloped land found within the watershed, the Mousam river is described as being of "statewide ecological significance". However, it is currently one of the most heavily dammed rivers in the state, which has inhibited the life cycles of sea-run species including Atlantic salmon and alewives. Many of the dams provide hydro-electrical power and their removal is heavily debated by local stakeholders. 

Resources

• Kennebunk Comprehensive Plan Update
• Mousam Lake Watershed Survey Report
• EPA: Nonpoint Source Program