Loch Raven Reservoir is an impoundment of the Gunpowder Falls that was built and maintained by the City of Baltimore to provide the Baltimore region with clean and safe drinking water.
Loch Raven Dam was initially constructed in 1915 with a spillway elevation of 192 feet above MSL and raised to its current spillway crest elevation of 240 feet above MSL in 1923.
The reservoir capacity is approximately 23 billion gallons and the impounded area is roughly 2,400 acres. The Loch Raven Reservoir watershed is divided into eight subwatersheds: Beaver Dam Run (20.73 sq. mi.), Dulaney Valley Branch (3.24 sq. mi.), Gunpowder Falls I (24.56 sq. mi.), Gunpowder Falls II (1.77 sq. mi.), Little Falls (53.63 sq. mi.), Loch Raven Reservoir (59.31 sq. mi.), Piney Run (12.39 sq. mi.), and Western Run (47.67 sq. mi.).
Raw water from Loch Raven Reservoir travels through a 7.3-mile long, 12-foot diameter tunnel for treatment at the Montebello Filtration Plants in Baltimore.
The primary purpose of the Loch Raven Reservoir is to provide high quality water to 1.8 million water supply customers in the Baltimore Metropolitan Region. Limited recreation is permitted on the reservoir property from sunrise to sunset daily. Swimming, wading or any other contact with the reservoir water is strictly prohibited.