Project Description
The Nunn's Mill Dam is located on the South Branch Raritan River in Washington Township, NJ. It was constructed over 100 years ago to power a small mill that has not been in use for some time. Approximately 40 feet of the dam is a concrete gravity spillway and the remaining 110 feet is an earthen embankment. The dam forms a 2.5-acre impoundment that accumulates sediment and has become shallow and partially vegetated. In August 2019, the NJ Department of Environmental Protection's Bureau of Dam Safety determined that the dam was damaged. As a result, the property owner was directed to conduct an official engineering inspection to bring the dam into compliance with the NJ Safe Dam Act, with recommendations for repair or removal.
The Cornell-Dubilier Electronics Trustees have proposed a restoration project to remove the Nunn's Mill Dam. The project will involve dam removal, management of upstream sediments, scour protection measures for the Four Bridges Road bridge downstream, stabilizing the river banks, and revegetating the site of the mill pond with native trees and shrubs, as well as restoration monitoring. Removal of the dam will reestablish aquatic connectivity for over 12 miles from the Coles Mill Dam to the next impediment upstream. In addition to improving water quality and stream habitat, this project will increase recreational fishing opportunities as the South Branch is a popular destination for trout anglers.
Parties Implementing Restoration
New Jersey Department of Environmental Protection; NOAA; Raritan Headwaters Association; U.S. Fish and Wildlife Service
DOI Project Representatives
Fish and Wildlife Service