EPA proposes "next generation" stormwater runoff controls for Washington D.C.

The U.S. Environmental Protection Agency (EPA) has issued a draft permit to the District of Columbia requiring the District to continue improving its Municipal Separate Storm Sewer System (MS4) program for controlling stormwater runoff.

“This permit can serve as a model to other municipalities for preventing runoff from washing harmful pollutants into streams and rivers in the Bay watershed,” said Shawn M. Garvin, the EPA’s mid-Atlantic regional administrator.

Medium and large MS4s such as the District’s are required by federal law to have permits covering their discharges. The permit announced today requires the District to take progressive steps that were not required by the old permit issued in 2004, including:

• Implementing a sustainable and enforceable approach to promoting low impact development and green infrastructure. This includes enhanced tree planting, green roofs and water reuse on-site to slow the rate of runoff from paved areas.
• Complying with strict discharge limits and new performance standards that require 90 percent on-site retention of storm flows at non-federal facilities for new development, redevelopment and retrofit projects.
• Increasing monitoring of total maximum daily loading (TMDL) or “pollution diet” for impaired waterways, including the Anacostia and Potomac rivers, Rock Creek and the Chesapeake Bay.
• Controlling and reducing trash through enhanced street sweeping and implementing the Anacostia River TMDL for a “Trash Free Potomac” by 2013.

The new permit conditions are necessary because large portions of impervious surfaces such as roads, rooftops and parking lots in the District channel stormwater directly into local streams and rivers. Improperly managed stormwater runoff can damage streams, cause significant erosion and carry excessive pollutants downstream and into the Chesapeake Bay.

The EPA is accepting public comments on the permit through June 4, 2010 and expects to finalize the permit within three months of the close of public review.