Stream restoration will help reduce flood risk, improve fish passage on Dewey’s and Quantico Creeks

Photo by Prince William County Communications Office 

Submitted: 

Restoration to improve the resiliency of the Possum Point Road culvert – located on Route 633 at the Prince William County and Town of Dumfries line – over Dewey’s Creek has wrapped up after nearly three months of work, interrupted by frequent heavy rainfalls and storms. Dewey’s Creek is a tributary of Quantico Creek, which is a tidal tributary of the Potomac River.

The restoration will improve sediment transport, water flow, and fish habitat. In addition, it will reduce flood risk to the surrounding community, which includes approximately 50 homes southeast of the culvert as well as the Possum Point Power Station, located on the banks of the Potomac River and serving the Washington, DC, metropolitan area.

Growing development within the watershed has increased the risk of culvert failure. Stormwater runoff from paved surfaces and yards causes flows to increase in the creek, leading to erosion, increased sediment accumulation at the culvert and constriction of water flow during high flow conditions.

Instead of replacing the culvert with something larger, the project involved restoring Dewey’s Creek for approximately 400 feet above the culvert. Stream banks were sloped and terraced to reconnect the creek to its floodplain, while rock elevation controls and riffles were constructed to eliminate sediment build-up at the culvert’s entrance and improve water flow and fish habitat.

The only freshwater eel species in North America, the American eel is migratory and leaves its habitat to enter the Atlantic Ocean during its spawning migration. The eels’ reproductive success relies heavily on open passage during migration to complete their lifecycle and ample diverse habitat for growth and maturation.

Coastal habitats, wetlands, and beaches will ultimately benefit from the upstream and inland-sources of sediment nourishment that will come from restoring natural sediment transport, flood storage and increased channel flow capacity of the creek.

The return on investment, both for conserving American eel and avoiding potential emergency repairs and safety concerns, is estimated at $3.13 million for the Prince William County and Town of Dumfries community. The project itself is one phase of a larger effort by Prince William County to restore Dewey’s Creek upstream of the culvert as well.

The $330,750 project was funded by the U.S. Fish and Wildlife Service through the Hurricane Sandy Disaster Relief Act of 2013. Partners on the project include the U.S. Fish and Wildlife Service, American Rivers, and both the Town of Dumfries and Prince William County. The Fish and Wildlife Service provided a $297,000 grant to the Town of Dumfries to do the work. Staff from the Prince William County’s Public Works Department acquired the project designs and engaged the contractor for the project. Prince William County has contributed over $300,000 toward the project.