WSSI designed and oversaw the demolition of the 1916 Ashland Mill Dam to restore anadromous fish passage to habitat and spawning grounds in the South Anna River and its tributaries upstream of the dam. The resulting Ashland Mill Dam Mitigation Bank provides stream mitigation credits to compensate for surface water impacts in the York River watershed.
The Challenge
The Ashland Mill Dam, which once provided hydromechanical power for flour mill operations, blocked anadromous fish passage, posed a safety hazard for river users, and trapped sediment in the river. WSSI staff and partners had to figure out how to remove the dam in a safe manner that also minimized environmental impact.
Our Solution
WSSI was part of a team led by Davey Mitigation to remove the 13-foot tall, 210-foot wide dam. This was the first dam removal project in Virginia to be permitted as a mitigation bank and the credits generated are used to offset environmental impacts for projects that fall within the local watershed. Privately funded and led, the dam removal project benefits Virginia citizens at no cost to taxpayers.
WSSI collaborated throughout all phases of the dam removal and ecological restoration with Davey Mitigation staff, from concept development through delivery and now with post-construction monitoring. To begin, we conducted existing conditions surveys and assessments that allowed us to plot the best path for removal and restoration. WSSI’s cultural resource specialists conducted a Phase I archeological investigation while our natural resource scientists delineated wetlands and other waters of the U.S. and Virginia, surveyed for endangered and threatened species in the project area (to include overseeing a mussel survey performed by others), and completed benthic macroinvertebrate sampling to better understand the health of the ecosystem. Our surveyors performed detailed bathymetric and topographic surveys and researched land records to determine ownership for contractual purposes. Engineers examined the upstream impoundment, to include water depths, bank characteristics, and sediment composition.
WSSI completed a floodplain assessment and was responsible for the mitigation and engineering design plans for the dam removal process and stream bank stabilization in the vicinity of the dam, as well as native vegetation plantings. WSSI’s ecosystem restoration specialists provided construction oversight for the eight-week construction demolition and site grading that began in September 2024. WSSI now provides post-construction monitoring, including cross-section measurements, water quality readings, sediment assessments, and drone-based photogrammetry to document shifts in the South Anna River bedform.
This local ecosystem restoration project’s success is felt beyond the former dam footprint. Site monitoring has documented the anticipated substrate sorting and physical changes in the river bedform as it transforms to a free-flowing river, and native trees planted along the riverbanks adjacent to the former mill during site restoration are thriving. Scientists with the Department of Wildlife Resources and Randolph Macon College have documented the presence of American shad, hickory shad, alewife, blueback herring, striped bass, American eel, and sea lamprey upstream of the former dam in the months that followed demolition.
WSSI’s work on this project was conducted in partnership with Davey Mitigation, Virginia Department of Wildlife Resources, Randolph-Macon College and Backwater Environmental.