One of the first major aqueduct projects in the United States, the Washington Aqueduct was commissioned by Congress in 1852, and construction began in 1853 under the supervision of Montgomery C. Meigs and the US Army Corps of Engineers. It followed closely after New York's Croton Aqueduct, built between 1837 and 1842, and Boston's Cochituate Aqueduct, built between 1846 and 1848. It was built from 1852 to 1863, placed in service in 1864, and with later alterations remains in service today.
A superlative illustration of early military involvement in the civil sector, the aqueduct epitomizes the emergence of the Army Corps of Engineers into the field of public works and consequent major economic influence. It is also a monumental engineering achievement of designer, engineer, and Civil War Quartermaster General Montgomery Meigs. The aqueduct system includes a masonry dam at Great Falls, six bridges including the 220-foot masonry arch at Cabin John (the world’s longest masonry arch when built), a mile of tunnels, twelve miles of conduit, brick air vents, and various control facilities. The water supply crosses Rock Creek and enters the city at the Pennsylvania Avenue (Meigs) Bridge, where it passes through arched cast-iron conduit tubes that also support the bridge. In the original bridge of 1861-62, these huge pipes were exposed, but they are now partially concealed by a 1916 granite facing and soffit.
The District portion of the aqueduct includes Dalecarlia Reservoir, a nine-foot diameter masonry conduit under MacArthur Boulevard (originally Conduit Road), and Georgetown Reservoir.
DC Inventory: March 3, 1979
National Register: September 8, 1973
National Historic Landmark: November 7, 1973