Eel River Headwaters Restoration – Plymouth, MA | SumCo - Specialized Civil and Ecological Construction

Eel River Headwaters Restoration – Plymouth, MA

The Eel River Headwaters Restoration has been a signature effort for the Commonwealth of Massachusetts environmental restoration efforts since its completion in 2010. This $2 million project designed and constructed between 2007 and 2010 included channel reconstruction, dam removals, culvert replacements, grading, and extensive plantings across a 60-acre site.

Benefits of the project include fish passage and habitat for diadromous and resident fish; improved water quality; establishment of rare Atlantic White Cedar swamp habitat; public education; and enhanced recreation along an existing trail system. The Town of Plymouth benefits from saving on costly infrastructure replacement, and the project aids in compliance with the requirements of the town’s groundwater discharge permit through nutrient reduction.

Date of Completion:

August, 2010

Owner:

Town of Plymouth, Massachusetts

Design Lead:

Inter-Fluve

Project Elements:

Removal of the Sawmill Dam
Restoration of 60 acres of diverse wetlands habitat
Excavation over 48,000 cubic yards of sediment
Creation two miles of new river channel
Replacement two road crossings
24,000 native tree and shrub plantings to re-establish a
rare Atlantic white cedar wetland

Years of site monitoring have uncovered important findings, such as renewed growth of sphagnum moss up to 4-inches in depth; thousands of Atlantic white cedar (AWC) seedlings; moss / AWC germination support; original AWC plantings now up to 12 feet tall, and plants plentiful in reconstructed channel areas potentially leading to elevated water temperatures and reduced dissolved oxygen levels, an observation causing reconsideration of the geometry of restored channels, especially where coldwater fish are present.

Techniques pioneered at Eel River have since been used at Tidmarsh Farms (Plymouth), Coonamessett River (Falmouth), and Cold Brook Preserve (Harwich) and will be soon applied elsewhere.