Washington Aqueduct

United States historic place

Washington Aqueduct

U.S. National Register of Historic Places

U.S. National Historic Landmark

The Union Arch Bridge carries the Washington Aqueduct across Cabin John Creek (2008)

Dalecarlia Reservoir & Treatment Plant

Location| 5900 MacArthur Blvd., NW
Washington, D.C.
Coordinates| 38°56′15″N 77°6′51″W﻿ / ﻿38.93750°N 77.11417°W﻿ / 38.93750; -77.11417Coordinates: 38°56′15″N 77°6′51″W﻿ / ﻿38.93750°N 77.11417°W﻿ / 38.93750; -77.11417
Built| 1853-1864
Architect| Montgomery C. Meigs
NRHP reference No.| 73002123
Significant dates
Added to NRHP| September 8, 1973
Designated NHL| November 7, 1973

The Washington Aqueduct is an aqueduct that provides the public water supply system serving Washington, D.C., and parts of its suburbs, using water from the Potomac River. One of the first major aqueduct projects in the United States, the 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. Portions of the Aqueduct went online on January 3, 1859, and the full pipeline began operating in 1864.[1]: 68 The system is owned and operated by the Corps of Engineers and has been in continuous use ever since. It is listed as a National Historic Landmark, and the Union Arch Bridge within the system is listed as a Historic Civil Engineering Landmark.

## Contents

* 1 Design and facilities
* 2 System expansion
* 3 Operations and service area
* 4 References
* 5 Further reading
* 6 External links

## Design and facilities[edit]

The centerpiece of the Aqueduct is a 12-mile (19 km) pipeline which connects the system's dam at Great Falls with the Dalecarlia Reservoir on the border with Montgomery County, Maryland. Portions of the Aqueduct went online on January 3, 1859, and the full pipeline began operating in 1864.[1]: 68 The pipeline runs along what is now MacArthur Boulevard, traversing some of the higher cliffs along the Potomac River.

The Washington Aqueduct Dam, upstream of Great Falls

The Union Arch Bridge carries the pipeline and MacArthur Boulevard over Cabin John Creek and the Cabin John Parkway near the community of Cabin John, Maryland. This bridge was the longest masonry arch bridge in the world for 40 years after its completion.[2] [3]

The Dalecarlia Reservoir serves as a primary sedimentation basin. A portion of the water from the reservoir is treated at the nearby Dalecarlia Water Treatment Plant and distributed to municipal water mains. The remainder of the water from the reservoir flows to the Georgetown Reservoir in the Palisades neighborhood of Washington. This facility serves as an additional sedimentation basin, and then the water flows through the Washington City Tunnel to the treatment facility at the McMillan Reservoir, after which it is pumped through city mains. The Dalecarlia Reservoir was modified in 1895 and 1935 to improve water quality and increase water supply.[1]: 99

## System expansion[edit]

Dalecarlia Water Treatment Plant

The system originally used a single pipe for water delivery, and did not have any water purification plants, relying instead on the reservoirs to act as settling basins. By the turn of the 20th century, however, Washington's growth and the high amount of sediment in the Potomac's water kept the reservoirs from doing their jobs well, and so the first treatment plant, a massive slow sand filter bed system, was installed at McMillan Reservoir, and was completed in 1905.[4]: Ch.4 The regular use of chlorine as a disinfectant began in 1923 at the McMillan plant. The McMillan plant was not replaced until 1985, when a rapid sand filter plant was opened adjacent to it.[1]: 124–125

In the 1920s, the aqueduct was upgraded with the addition of a second pipe from Great Falls to Dalecarlia, along with several new reservoirs and a pumping station, A rapid sand filter plant was built at Dalecarlia Reservoir, which went online in 1927.[4]: 204–205 The Dalecarlia plant is the larger of the two plants in the system, having been upgraded in the 1950s, and is the plant that serves the Virginia communities that use the Aqueduct.

In 1926, Congress approved selling water from the aqueduct to Arlington County, Virginia. [1]: 105 A new water supply pipe was constructed at Chain Bridge and service to Arlington began in 1927. Additional pipes were built as Arlington's population grew, including a pipe built under the Potomac River. In 1947 Congress approved adding the city of Falls Church, Virginia to the aqueduct system, and nearby portions of Fairfax County, Virginia were added in the 1960s.[1]: 129–130

The Corps built an additional intake and pumping station at Little Falls in 1959.[4]: 256

## Operations and service area[edit]

The Aqueduct is a wholesale water supplier. The communities it serves are responsible for billing customers and managing water mains. The service area is:

* Washington, D.C., and most of the federal installations in the city (via DC Water)
* Arlington County
* The city of Falls Church and part of Fairfax County (particularly McLean).

## References[edit]

1. ^ a b c d e f Ways, Harry C. (1996). The Washington Aqueduct: 1852-1992. Baltimore, MD: U.S. Army Corps of Engineers, Baltimore District.
2. ^ "Washington Aqueduct". U.S. National Park Service. 2021-04-21.
3. ^ Norman Metzger (March 2004). "A Sycamore Neighbor: The Washington Aqueduct". Sycamore Islander.
4. ^ a b c Scott, Pamela (2007). Capital Engineers: The U.S. Army Corps of Engineers in the Development of Washington, D.C., 1790-2004. Washington, D.C.: U.S. Army Corps of Engineers. ISBN 978-0160795572. Archived from the original on 2009-07-22. Retrieved 2014-09-02. Publication No. EP 870-1-67.

* "The Corps Has Helped Solve Urban Water Problems Since 1824 - Beginning at the White House". Headquarters; History. Washington, D.C.: U.S. Army Corps of Engineers. October 2002. Historical Vignette 059. Archived from the original on 2011-06-04.

## Further reading[edit]

* Chick, H.M. (1934). History and construction of the aqueduct leading to McMillan Park, Washington, D.C. (Thesis). College Park, MD: University of Maryland. ARCV 72-115.41. Records of Phi Mu, Special Collections, University of Maryland Libraries.

## External links[edit]

Wikimedia Commons has media related to Washington Aqueduct.

* U.S. Army Corps of Engineers: official Washington Aqueduct website
* National Park Service.gov: A longer history of the system, from the C&O Canal site Archived 2014-01-07 at the Wayback Machine
* National Park Service.gov: National Historic Landmarks Program & the Washington Aqueduct
* Maps of the Washington Aqueduct, Md. and Washington D.C. : to accompany supplemental report of Chief Engineer dated Feb. 22nd 1864
* Washington Aqueduct, Montgomery County, Inventory No.: M: 29-49 at Maryland Historical Trust website

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