Dam Removals: Riegelsville
The Lower Musky is Freed of Three Obstructions
The Riegelsville Dams were built over 200 years ago, but were unused for the past 100 years. When the mills powered by the dams were shut down, the structures were obsolete; left unused, they degraded and began to break down. An examination of aerial photos taken over the past century reveals that most of the structures were washed away during the 1970's. By the mid-1980's all that remained was what we have long referred to as the Riegelsville Dam "remnants".
Prior to removal of the remnants in early August 2011, the only remaining components of the dam were the masonry abutment walls, earthen embankments outside of the channel, and the timber crib foundation in the riverbed. The upstream stone dam remained in place, its only function for the past 150 years being to back up water and inhibit fish passage. The timber crib foundation was also high enough to prevent the upstream migration of certain species and it was certainly a safety hazard for paddlers and anglers. Additionally, the existence of the timber crib foundations and the stone dam created a backwater and limited the river's natural sediment carrying capacity.
Beginning in August 4, 2011 the MWA and partners began the process of removing these structures. Partners along the path to removal included two private landowners, NJ Fish and Wildlife, U.S. Fish and Wildlife Service, National Park Service, NJ Trout Unlimited and the NJ Department of Environmental Protection. Funders were the National Fish and Wildlife Foundation, Cora Brooks Foundation, Conservation Resources Inc., Corporate Wetlands Restoration Partnership and the U.S. Fish and Wildlife Service. Engineering plans and oversight was done by Princeton Hydro LLC, and removal and restoration was done by Urbani Fisheries. Restoration of the upper stone dam area was done by Trout Unlimited Home Rivers Initiative Coordinator, Brian Cowden, along with several TU volunteers. To conduct historic oversight of the removal, the NJ State Historic Preservation Office hired Hunter Research LLC.
The project site, Riegelsville, NJ, is just upstream of the confluence of the Musconetcong and Delaware Rivers. Existing timber remnants of the Riegelsville Dam were removed and the channel was restored for one mile upstream to the Finesville Dam (now removed). Optimizing fish habitat in rivers is based on a set of techniques referred to as "bed manipulation." This involves the stabilization of banks and reorganizing the native elements in the river to favor fish and their food base organisms, thereby allowing the river to reach its full potential as a fishery.
Prior to removal, anglers could catch American shad and an occasional striped bass below the Musconetcong's first dam, the Finesville dam. River herring are found in the Delaware River upstream of the confluence with the Musconetcong as far north as Easton, Pennsylvania. Based on the Musconetcong's excellent water quality, it is expected that barrier removals such as this one will bring that species into the lower river to spawn.