The The U.S. Environmental Protection Agency (EPA) faces opposition from both environmental groups and industry over the District of Columbia’s landmark municipal separate storm sewer system (MS4) permit. The permit is considered a model for future MS4 permits across the region and the country. It requires infiltration-based stormwater management techniques, such as green roofs and bioretention facilities, to retain a minimum of 1.2 in. (30 mm) of stormwater runoff onsite, representing 90% of the rainfall events that occur in the Washington, D.C., area in a typical year.
However, a petition filed by environmental groups on Nov. 4 argues that EPA should control the permit compliance schedule, and that the permit does not mandate water quality compliance as long as facilities comply with the retention standard. In contrast, industry groups petition that some of the permit’s numeric goals are not achievable, and that there is a lack of clear distinction between utilities’ responsibilities and those of the District of Columbia.