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Castle Gatehouse, Washington Aqueduct is a Washington, DC pump station located on the Washington Aqueduct in the Georgetown Reservoir. Built between 1899 and 1901, the Castle Gatehouse was a commission of the US Army Corps of Engineers by Congress to give Washington, DC access to a source of water. It was designated as a National Historic Landmark in November of 1973, and shortly after is as added to the National Register of Historic Places in March of 1975. Today, the gatehouse continues to be monitored and managed by the US Army Corps of Engineers.


  • A view of the gatehouse.

In 1850 and 1852, Acts of Congress were passed tasking the US Army Corps of Engineers with providing Washington, DC with a workable water supply. The Army Corps of Engineers began working on the supply line in 1853, opting to build a pipeline using the Potomac River as its source. Construction on the pipeline took a significant amount of time, and it was not until 1859 that portions of the pipeline even began to be operational. Though the city of Washington, DC still needed water despite the fact that the pipeline was not complete, the Army Corps of Engineers diverted water from Little Falls Branch for a time until the pipeline was eventually completed in 1864. Though the pipeline was finished and the city technically had access to a water supply, the water was completely unfiltered, and would often even be dirty, muddy water. The city worked with this water supply for around forty years, and around the turn of the century, the Army Corps of Engineers worked to improve the system.

In 1899, construction began on a gatehouse for the water supply, which was modeled after the Army Corps of Engineers’ insignia, and was designed to look somewhat like a castle in appearance, and it was completed in 1901. Additionally, a treatment plant was set under construction, and in 1905, it was providing Washington, DC with filtered, purified water. On November 7th, 1973, the gatehouse was designated as a National Historic Landmark, and on March 13th of 1975, it was placed on the National Register of Historic Places. Today, the gatehouse still sees active use and is monitored and maintained by the Army Corps of Engineers.

National Register of Historic Places. Castle Gatehouse, Washington Aqueduct. March 13, 1975. Accessed August 12, 2016. http://focus.nps.gov/pdfhost/docs/NRHP/Text/75002048.pdf