Weweantic River Restoration and Horseshoe Mill Dam Spillway Removal

The Horseshoe Mill Dam spanned the Weweantic River at the head-of-tide and was the first barrier to fish passage on the river. The dam, built in 1827, supported a metal forge mill whose buildings were removed in 1966. The surrounding property had since been allowed to revert to woodland with some open tall grass areas and approximately 10,000 feet of walking trails as a part of a public park. At the start of the project, the impoundment encompassed approximately 91 acres of largely vegetated wetlands ranging from floating emergent vegetation to emergent marsh and forested wetlands, all of which was predominantly open water in the past when the dam was fully functioning and at maximum height.

Princeton Hydro was contracted by Buzzards Bay Coalition to progress the Horseshoe Mill Dam removal by providing design and permitting services, conducting site investigation and analysis including sediment testing, guiding the regulatory review process, assisting with project bidding, and providing engineering construction oversight. Additional project partners included U.S. Fish and Wildlife Service, NOAA, and Luciano’s Excavation, Inc. (construction contractor). It was funded through the Bouchard 120 Natural Resource Damage Trustee Council, a federal-state entity comprised of the U.S. Fish & Wildlife Service, NOAA, the State of Rhode Island, and the Commonwealth of Massachusetts.

The removal of the dam was initiated in December 2019 and finished in early 2021. It restored more than three miles of habitat for fish like river herring, white perch, and rainbow smelt. In April 2021, for the first time in over 150 years, migratory fish swam unimpeded from Buzzards Bay to lay their eggs in freshwater upstream. Prior to this removal, migratory fish could not make it past the large dam structure to swim upstream to their important breeding grounds.