The Anacostia River is an 8.5 mile long tidal river within the Anacostia watershed. The Anacostia watershed is 176 square miles and includes parts of the District, and Montgomery County and Prince George’s County, Maryland. Nearly one million people live in this watershed, either directly on the Anacostia River or on one of the many streams that connect to it. Whatever happens in any of these streams and communities affects the Anacostia River.