The U.S. Environmental Protection Agency (EPA) on Oct. 5 approved the District of Columbia’s , mandating 350,000 ft of green roofs. The permit encourages other forms of green infrastructure as well requiring new development with footprints of 5000 ft or larger to retain 1.2 in. of rainfall over a 24-hour period. The permit also calls for retrofits on 18 million ft of impervious surfaces and a reduction in the trash loading of the Anacostia River by at least 103,000 lb/yr.