Project Description
To compensate for injuries to diadromous fish, the Nyanza Natural Resource Trustees provided funding to conduct a feasibility study to examine the actions necessary to improve fish passage in the Concord River. Diadromous fish, such as alewives, American eels, American shad, blueback herring, and sea lampreys, historically migrated through the streams and rivers of the Sudbury-Assabet-Concord (SuAsCo) River Watershed to reach their spawning grounds until the construction of dams restricted these pathways. Three barriers were examined in this study: Middlesex Falls, Centennial Falls Dam, and Talbot Mills Dam. The downstream most barrier, Middlesex Falls, is a natural ledge surrounded by the remaining concrete abutments of the Middlesex Dam that was breached during a flood in the 1980s. Though not a physical obstruction, the abutments create a hydraulic restriction that only allows passage during limited flow conditions. The Centennial Falls Dam is a low-head dam that supplies water to a hydroelectric facility through a small power canal. A fish ladder was constructed in 1990 but the National Marine Fisheries Service (NMFS) and Massachusetts Division of Fisheries and Wildlife (MassWildlife) report that shad and river herring may be attracted to the base of the dam rather than the entrance of the fish ladder due to differences in flow. The Talbot Mills Dam is a granite block dam that was constructed in 1828. The dam does not have a fish passage structure, does not meet dam safety regulations, and increases upstream flooding.
The feasibility study demonstrated that diadromous fish passage is possible on the Concord River. Channel improvements at Middlesex Falls may reduce flow turbulence to more acceptable ranges for upstream fish passage. Minor modifications can be made to the fish ladder at Centennial Falls Dam to improve passage. There are also opportunities at the site for stewardship and public education to ensure the effectiveness of passage at this dam. The Talbot Mills Dam was found to be the primary impediment for diadromous fish in the watershed. Partial removal of the dam would provide effective passage for diadromous species, decrease upstream flooding, and improve water quality, aquatic habitat connectivity, and the natural sediment regime of the river. It was also demonstrated that it would be technically feasible to install a fishway, including a Denil-style ladder, eel ramp and downstream bypass notch, to improve fish passage at Talbot Mills.
Restoration Land Ownership
County or Municipal; Private
Parties Implementing Restoration
Massachusetts Department of Fish and Game ; NOAA
DOI Project Representatives
Fish and Wildlife Service