The District of Columbia Water and Sewer Authority (i.e. WASA or D.C. Water) is an independent authority of the D.C. government that provides drinking water and wastewater collection in Washington. WASA purchases water from the historic Washington Aqueduct, which is operated by the U.S. Army Corps of Engineers. The water, sourced from the Potomac River, is treated and stored in the city's Dalecarlia, Georgetown, and McMillan reservoirs. The aqueduct provides drinking water for a total of 1.1 million people in the District and Virginia, including Arlington, Falls Church, and a portion of Fairfax County.[210] The authority also provides sewage treatment services for an additional 1.6 million people in four surrounding Maryland and Virginia counties.[211] Pepco is the city's electric utility and services 793,000 customers in the District and suburban Maryland.[212] An 1889 law prohibits overhead wires within much of the historic City of Washington. As a result, all power lines and telecommunication cables are located underground in downtown Washington, and traffic signals are placed at the edge of the street.[213] A plan announced in 2013 would bury an additional 60 miles (97 km) of primary power lines throughout the District.[214] Washington Gas is the city's natural gas utility and serves over one million customers in the District and its suburbs. Incorporated by Congress in 1848, the company installed the city's first gas lights in the U.S. Capitol building, White House, and along Pennsylvania Avenue.[2