Whale Rock Reservoir is a reservoir near Cayucos in San Luis Obispo County, California. The reservoir was formed by the building of Whale Rock Dam on Old Creek by the Whale Rock Commission. It is a 193 ft tall earthfill dam that was completed in 1961. The reservoir has a capacity of 40,662 acre.ft. The watershed has an area of 20.6 mi2. It provides drinking water for the city of San Luis Obispo, the California Men's Colony, Cal Poly, and the Cayucos Area Water Organization. The water is brought to San Luis Obispo by the 17.6 mi long, 30 in diameter Whale Rock Conduit.