The city's first water system followed soon after New York’s Croton Aqueduct (1837-42), and Boston’s Cochituate Aqueduct (1846-48). 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. Notable structures include the inscribed sluice tower at Dalecarlia Reservoir, superintendent’s house at Dalecarlia, and Georgetown Reservoir with its air vent and Castle Gatehouse (built 1901). Contributing structures date from 1853 to 1880.
National Register: September 8, 1973
National Historic Landmark: November 7, 1973
DC Inventory: March 3, 1979