The Anacostia is severely impacted by fecal bacteria from several different sources. In Maryland, stormwater runoff causes erosion that exposes sanitary sewer pipes, resulting in broken pipes and the discharge of raw sewage. Another surprising source of fecal bacteria in Maryland is animal waste. The large amount of impermeable surface means that fecal bacteria from domestic and wild animals is washed into the river instead of soaking into the ground during rain events.
In DC, the main source of fecal bacteria is from Combined Sewer Overflows (CSOs). This is the sewage system in the older part of the city. Both stormwater runoff and sanitary sewage flow in the same pipes. Due to the growth of the District over the last hundred years, this system is now easily overwhelmed by rain events. This triggers valves that discharge raw sewage into the river to prevent it from backing up into homes. Currently, overflows contribute 1.3 billion gallons of raw sewage and stormwater into the Anacostia River annually.
Combined sewer overflow discharge point
Pollution may occur during rainfall
Legal action in 1999 by AWS and its partners resulted in a consent decree with DC Water which requires them to fix this problem, a multi-billion dollar effort known as the Clean Rivers Program. This ongoing effort utilizes massive underground storage tunnels to contain wastewater until it can be treated at the Blue Plains facility and large-scale green infrastructure projects to let stormwater naturally infiltrate into the ground or otherwise be treated on site to lessen impacts on the combined sewer system during heavy rain events. Modifications to this plan were proposed by DC Water in 2015 that could potentially mean fewer tunnel sections and more green infrastructure in the Rock Creek and Potomac River sections. The 13.1 mile long tunnel to control CSOs to the Anacostia, however, will continue as planned and will be complete ahead of schedule with 81% of CSOs reduced in 2018 and 98% of CSOs reduced in 2022.
The Water Quality Report Card shows how Bacteria levels in the water are improving.