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Maryland's National Register Properties

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Washington Aqueduct
Inventory No.: M: 29-49
Date Listed: 11/7/1973
Location: MacArthur Boulevard , Potomac, Montgomery County
Category: District
Period/Date of Construction: 1853-1880
Architect/Builder: Architect: Montgomery C. Meigs
NHL Date: 11/7/1973
Description: Construction of the Washington Aqueduct, a water supply system for Washington, D.C., began in 1853 by the U.S. Army Corps of Engineers. Designed by Captain Montgomery C. Meigs, the system consisted of a 12-mile, underground conduit extending from the Great Falls of the Potomac River in Maryland to the District of Columbia. The Aqueduct system is 60 feet in width throughout most of its length, but widens at three locations: Great Falls, Dalecarlia Reservoir, and the Georgetown Reservoir. These three areas contain the majority of the above-ground resources constructed as part of the original Aqueduct system. The Aqueduct was designed as a gravity-fed system. A descent of nine inches every 5,000 feet allows water to flow through the conduit by gravity. To maintain this constant slope, the conduit required the construction of 11 tunnels, 26 culverts, and six bridges. Air vents, waste weirs, gatehouses, a receiving reservoir, and a distributing reservoir also were built as part of the original system. These support structures were integral elements of the Meigs plan. Significance: The original Washington Aqueduct system is nationally significant as representative of the national pattern in 19th century public works in which public water systems were introduced as part of municipal services. The system is also significant for its design by Montgomery C. Meigs, an important 19th century architect-engineer. The period of significance for the Washington Aqueduct is defined as 1853-1880. This period extends from the approval to the completion of the Meigs plan for the water system. Although Meigs' direct involvement in the project lasted only until 1862 when he was appointed Quartermaster General of the U.S. Army, his plans were carried out by his successors with only minor modifications. Chief Engineer William R. Hutton assumed supervision of the project for one year following Meigs' departure, and was succeeded by Chief Engineer Silas Seymour, who supervised construction from July 1863 to 1865. Under Seymour's supervision, water from the Potomac first reached the city via the new Aqueduct. After 11 years of construction, the Aqueduct first delivered water to the city of Washington in July 1864. Since that time, the aqueduct system has undergone a series of upgrades and expansions to meet the demands of Washington's increasing population. A second distributing reservoir was created during the 1880s, with a four-mile tunnel connecting it to the Georgetown Reservoir. The new McMillan Reservoir went into operation when the tunnel was completed in 1902, with a new slow sand filter plant nearby, which became operational in 1905.A second conduit and water filtration facility were added in the 1920s, and in 1926 service was extended to provide water to Virginia. In the mid-to-late 20th century, additional improvements and upgrades ensured that the Washington Aqueduct continues to provide an adequate and high-quality water supply to its service area.


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