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This month, we’re celebrating the sixth anniversary of the Hughesville Dam Removal. The removal of the 18-foot-high, 150-foot-long dam not only marked a major milestone in restoring the Musconetcong River, it also led to the speedy return of the American shad (Alosa sapidissima), a species that had been absent from the area for 200+ years.
The Hughesville Dam was constructed by John L. Riegel and the Warren Manufacturing Company in the late-1800s to provide water to power the former paper mill located in Hughesville. The dam, a 12-foot-high timber crib and rock fill dam, spanned the Musconetcong River from Holland Township, Hunterdon County to Pohatcong Township, Warren County. The structure was not in compliance with NJDEP Dam Safety Standards and was creating a blockage to catadromous and local fish passage.
Musconetcong Watershed Association hired Princeton Hydro to investigate, design, permit, and oversee the decommissioning of the Hughesville Dam, and conduct related river restoration work within the Musconetcong River. The Hughesville Dam was the fifth dam on the Musconetcong River designed for removal by Princeton Hydro.
As part of the dam removal project, 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.
On Thursday, Sept 8 2016, the project team made the first notches in the Dam. Sally Jewell, Secretary of the Interior during that time, toured the project site and held a press conference to commemorate the initial dam breach and celebrate the exciting news. Jewell called the project a “model for collaborative conservation.”
In addition to the Honorable Sally Jewell, NJDEP Commissioner Bob Martin, and U.S. Army Corp of Engineers, Philadelphia District Commander Lt. Colonel Michael Bliss, also participated in the press conference to discuss the importance of the Hughesville Dam removal and dam removal in general.
The entire dam removal took nearly three months, but you can watch the sped-up version here:
The project was supported by many partners and funded largely by the USFWS through the Department of the Interior (DOI) under the Hurricane Sandy Disaster Relief Appropriations Act of 2013.
The removal of the obsolete Hughesville Dam marked another major milestone of restoring the Musconetcong River. The removal is part of a larger partner-based effort led by the Musconetcong Watershed Association to restore the 42-mile Musconetcong – a designated “Wild and Scenic River” – to a free-flowing state.
Removing the dam opened nearly six miles of the Musconetcong to migratory fish, such as American shad, that spend much of their lives in the ocean but return to rivers and their tributaries to spawn. The removal was completed in November 2016 and in the Spring of 2017, schools of American shad were observed above the dam, after 200+ years of absence. Shad are a benchmark species indicative of the overall ecological health and diversity of the waterway.
Other benefits of the dam removal include eliminating a public hazard due to the deteriorating nature of the dam; restoring the natural of floodplain functions and values of the area; restoring native stream substrate and habitat; and increasing river fishing and recreation opportunities.
To read more about the Musconetcong Watershed Association, click here. To read about another dam removal project along the Musconetcong River, click here.
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