All surface waters in the District of Columbia flow to the Potomac River either directly or through tributaries such as Rock Creek and Anacostia River. The Potomac River is the second largest tributary flowing into the Chesapeake Bay. The National Mall and Memorial Parks is located immediately adjacent to the river, the Tidal Basin, and the Washington Channel. Water quality for all three water bodies is currently designated as impaired. See the District Department of the Environment's website for the most recent Water Quality Assessment.
The park is participating in District-wide efforts to identify strategies to improve stormwater management in order to protect the Potomac River and the Chesapeake Bay. The park provides ecosystem services through conservation of tree canopy and vegetated surfaces throughout the city, which help by allowing for stormwater infiltration, as well as through implementation of Best Management Practices (BMPs) and Low Impact Development (LID) strategies during construction activities and roadwork. For example, in 2012 the park installed its first porous concrete at a maintenance yard parking lot. This will help to control runoff at the source by allowing water to infiltrate through the pavement.
How you can help at the park and at home:
The park installed its first porous concrete at the Brentwood Maintenance Facility in Northeast DC; the first several inches of rain falling on this lot will percolate through the pores of the pavement, rather than running into the storm sewer system.