The reservoir in Washington where a body was found Saturday night was taken out of service temporarily and treated with extra chlorine, authorities said.

The McMillan reservoir, where the body was found, stores untreated water, which goes through purification before it is distributed to water customers, said a spokeswoman for DC Water, the District’s water utility.

The spokeswoman, Pamela Mooring, said late Monday that the utility’s source was switched from McMillan to the Dalecarlia treatment plant, which is on MacArthur Boulevard NW, while the water in McMillan was treated with extra chlorine. The procedure was “out of an abundance of caution,” she said, adding that the McMillan site is now back in service.

The Washington Aqueduct, operated by the Army Corps of Engineers, takes water from the Potomac River, treats it at the McMillan and Dalecarlia sites and sells it to DC Water for distribution, according to an Aqueduct web page. Both McMillan and Dalecarlia are federally-owned and operated, the Aqueduct said.

According to police, the body was first seen around 7:30. Mooring said it was spotted by reservoir security. When officers arrived, they found the body submerged, police said in a statement.

No obvious cause of death was determined at the scene, police said. They said the body, that of a black male, was taken to the medical examiner’s office for an autopsy. No information about a name has been provided.

Bodies have been found from time to time in Washington area waterways, such as the Potomac and Anacostia Rivers, and the Tidal Basin. However, access to those waterways is largely unobstructed. By contrast, the McMillan Reservoir is surrounded by a chain link fence that is topped with barbed wire, and it was not clear how the body ended up in the reservoir.