McMillan Park Reservoir Historic District

The city’s first water treatment plant was both a victory for public health and a monument to the City Beautiful movement.

Constructed over a period of decades at the turn of the 20th century, the McMillan Park Reservoir’s original slow sand filtration system was DC’s first water purification facility. Connected to the Washington Aqueduct, the reservoir treated the city’s public water supply and in so doing eliminated typhoid and malaria epidemics in DC.

The McMillan Park Reservoir’s name honors Senator James McMillan of Michigan, best known for his work with the Senate Park Improvement Commission. The commission’s McMillan Plan sought to redesign the National Mall to better reflect Pierre L’Enfant’s original plan for the city. Although McMillan did not live to see the reservoir completed, his work and his collaboration with major figures of the City Beautiful movement, such as Frederick Law Olmsted Jr., Charles F. McKim, Herbert Adams, and Charles Platt are reflected in the original design of McMillan Park. This is especially true of Olmsted’s landscaping, which concealed the water treatment facility under a public park. McMillan Park remained open to and popular with the public until World War II, when it was fenced off for fear of enemies sabotaging the city’s water supply.

In the 1980s, the original filtration system was decommissioned, having become obsolete, and a new treatment facility operates next to the old one. In recent years, debates over redeveloping much of the original McMillan Park have resulted in various plans for altering the space. The McMillan Reservoir and Sand Filtration Site remains on DCPL’s Most Endangered Places list.

DC Inventory: August 21, 1991
National Register: February 20, 2013 (McMillan Park Reservoir Historic District)



1st Street and Michigan Avenue, NW