Hughesville Dam Removal and River Restoration

Princeton Hydro was contracted by the Musconetcong Watershed Association to investigate, design, permit and oversee the decommissioning of the Hughesvill Dam, along with the associated river restoration within the Musconetcong River. This was the fifth dam on the Musconetcong River designed for removal by Princeton Hydro.

The Hughesville Dam was constructed circa 1880 and was a timber crib and rock fill dam. The dam was 12 feet in total height from the top of the spillway to the bottom of the downstream apron with abutments about 20 feet in height. As part of the dam removal, Princeton Hydro completed a feasibility study in 2012 and initiated designs in 2014 to decommission the spillway and restore the impoundment. To assess potential sediment impacts, vibracoring was conducted and sediment analysis and quantification of the volume of impounded material was completed. Princeton Hydro worked with the NJDEP to assess the quality of sediment and determine its ultimate disposal.

As part of the design, the 21,000 cubic yards was proposed to be hydraulically dredged to adjacent existing on-site lagoons at this now defunct paper mill plant. The pre-existing and proposed hydraulics were assessed to understand impacts to an upstream bridge and downstream flood water surfaces following removal. Geomorphic assessments and utilization of nature-based restoration techniques were utilized to design a new river channel within the former impoundment.

Following the completion of design, applications were prepared for submission to NJDEP’s Land Use Regulation Program and Dam Safety Section, as well as the Hunterdon County Soil Conservation District (Warren County ceded jurisdiction to Hunterdon County). Princeton Hydro also applied for right-of-way permits to reinforce the foundation of an upstream county bridge as well as construct project access from a county road. Following the receipt of permits, Princeton Hydro assisted in the procurement of a contractor and provided construction administration services.

The project was completed in December 2016 and in the Spring of 2017, schools of American shad (Alosa sapidissima) were observed above the dam, after 200+ years of absence.