County on Track to Meet Chesapeake Bay Reduction Requirements

The Prince William Board of County Supervisors recently saw a presentation on the county’s Watershed Improvement Program and the progress towards meeting the Chesapeake Bay Total Maximum Daily Load, or Bay TMDL, reduction requirements for the county.

Prince William County sits in the Chesapeake Bay watershed along with parts of New York, Pennsylvania, Maryland, Washington, D.C., West Virginia and Delaware.

The Bay TMDL sets pollution limits in the Bay watershed for nitrogen, phosphorous, and sediment. These limits are divided by jurisdiction and major river basin based on a complex watershed model. For localities that run a stormwater management program, the Commonwealth requires a permit to discharge stormwater. This permit is called the Municipal Separate Storm Sewer System Permit, or MS4, and is administered by the Virginia Department of Environmental Quality with oversight by the U.S. Environmental Protection Agency. The MS4 permit requires that localities achieve pollutant reductions over three, five-year permit cycles through the implementation of water quality improvement projects.

Stream restorations and stormwater retrofits are two primary projects that the Prince William County Public Works Department implements to meet Bay TMDL reductions.

Stream restoration projects create sustainable stream channels that minimize erosion, reconnect the floodplain, protect infrastructure and create a diverse forest community. Stormwater retrofit projects increase the pollutant removal efficiency of existing stormwater management facilities. Reforestation replaces impervious surfaces such as concrete and asphalt with native forest trees and meadow plants.

The Public Works Department identifies projects based on watershed management studies, staff evaluations and knowledge of the county, and complaints. Public Works also coordinates with the Prince William County Department of Parks, Recreation and Tourism and the Prince William County Service Authority. So far, the Public Works Department has completed eight watershed management studies.

Upcoming stream restoration upgrades include the Mayhew Park Stream Restoration Project in the Bull Run Watershed, Cow Branch Phase Four Stream Restoration in the Neabsco Creek watershed, the Chinn Park Stream Restoration in the Occoquan River watershed, Powell’s Creek Phase Three Stream Restoration in the Powells Creek watershed, and Upper Dewey’s Creek Stream Restoration in the Quantico Creek watershed. The upcoming projects include work on eight water quality retrofits of existing stormwater management facilities dispersed throughout the county.

The projects identified above are included in the county’s Bay TMDL action plan and prioritized based on several criteria including the cost of reducing pollutants, the percent of impervious surfaces, age of the watershed study, ownership, accessibility, downstream channel condition and other needs such as infrastructure protection.

The county has until 2029 to achieve 100 percent of its assigned pollutant reductions. As of 2022, the county has achieved just over 70 percent of the reductions for sediment and phosphorous, and just

under 40 percent reductions for nitrogen. Based on the projects currently planned, the county is on track to achieve all of its required reductions by the deadline.