Project Description
Island Farm Weir (IFW) is a low head dam located immediately downstream of the confluence of the Raritan and Millstone Rivers. IFW was constructed in 1994 to supplement New Jersey's public water supply and is currently the downstream-most barrier on the Raritan River. A concrete vertical slot fishway was installed during the construction of IFW but recent fish passage studies conducted by the NJ Department of Environmental Protection (NJDEP) and Rutgers University found that fish passage is relatively poor, especially for anadromous species. The impoundment created by IFW can supply upwards of 225 million gallons of water per day in summer months. Due to the importance of IFW to the public water supply, the dam is not under consideration for removal.
To enhance fish passage at IFW, the installation of a nature-like rock ramp fishway has been proposed. This new technology uses rock features to simulate the natural river conditions that fish need to pass over the IFW. The new nature-like fishway will reestablish fish movement in the Raritan River, make the area safer for recreational kayakers, and preserve the dam’s primary function in helping maintain the local public water supply. The proposed design includes a rock arch rapids fishway that spans the full length of the weir. At least eight boulder arches will be constructed and positioned appropriately to provide adequately sized zones of passage, resting pools, water depths, and flow velocities to facilitate the passage of American shad and river herring. A portion of the flow will be diverted for the sediment bypass channel and water intake system. Design plans for the fishway were developed using funding from the American Cyanamid Natural Resource Damage settlement for in-river injury. Funding to improve the final design and construct the fishway will be provided by the Cornell-Dubilier Electronics Trustees.
Restoration Land Ownership
New Jersey American Water; Private
Parties Implementing Restoration
New Jersey Department of Environmental Protection; NOAA; USFWS
DOI Project Representatives
Fish and Wildlife Service