Freeing the Musky: Observations Following Dam Removal on the Musconetcong River, NJ
Earlier this summer, I spent a day working in the cool, shallow water of the Musconetcong River. The Musky, as it’s known locally, drains 158 square miles of rural New Jersey and is a major tributary of the Delaware River. Over the last several years, American Rivers has been working closely with a group of partners – including environmental non-profits, state and federal resource agencies, and private landowners – to “Free the Musky” by removing numerous outdated, low-head dams that impede the movement of resident and migratory fishes, reduce habitat quality and availability, contribute to streambank erosion, and pose a threat to recreational paddlers.
So far, the Lower Musconetcong River Restoration Partnership, working under the leadership of the Musconetcong Watershed Association (MWA), has successfully removed four dams: Gruendyke Mill Dam (2008), Seber Dam (2009), Riegelsville Dam (2011), and Finesville Dam (2011).
With plans for additional projects in the future, our group is interested in understanding how dam removal is impacting the river and how we might use this information to inform future projects. I worked with the MWA’s Monitoring Coordinator, Nancy Lawler, to develop a monitoring plan, and we recently spent the day with a small team of volunteers assessing post-removal substrate characteristics in a stretch of river that was previously inundated by the Finesville Dam. I led our team in conducting Wolman pebble counts— a method that consists of randomly selecting and measuring hundreds of pebbles within the study reach to determine the composition of the riverbed. The work is simple, but yields important data that allows us to inexpensively track changes following the removal of a dam.
We are beginning to observe coarser bed material as finer particles, like silts and sand, are slowly flushed out of the system. These changes to streambed habitat may also lead to shifts in macroinvertebrate community composition— another factor that we are monitoring as part of the dam removal effort.
While standing in the river on that hot July day, I was reminded how quickly dam removal can positively affect a river. Dam removal immediately eliminates an obsolete structure and often leads to rapid, visible improvements in stream habitat quality and availability.