Little Falls Branch, a 3.8mi tributary stream of the Potomac River, is located in Montgomery County, Maryland. In the 19th century, the stream was also called Powder Mill Branch. It drains portions of Bethesda, Somerset, Friendship Heights, and the District of Columbia, flows under the Chesapeake and Ohio Canal, and empties into the Potomac at Little Falls rapids, which marks the upper end of the tidal Potomac.HistoryIn the mid-19th century, the stream served as an interim water source for Washington, D.C. The Dalecarlia Reservoir was built on the D.C.-Maryland border next to Little Falls Branch. A dam was built on the stream, and water was diverted into the reservoir starting in 1859. In 1864, with the completion of the Washington Aqueduct, the Potomac River became the city's principal water source. However, muddy water from Little Falls Branch continued to flow into the reservoir, and a bypass pipe was built to channel the aqueduct water to another city reservoir, the Georgetown Reservoir. In 1895 construction was completed to fully divert the stream from the Dalecarlia Reservoir.
