Lower Otay Reservoir, reservoir in San Diego County, California, United States

Lower Otay Reservoir is an artificial lake in San Diego County formed by a dam with a gently curving shoreline. The water reaches depths of over 100 feet in some spots, and the surface stretches wide when the lake is full.

Lower Otay Dam, a rock-fill structure 125 feet high, was built in 1897 by the Southern California Mountain Water Company on Rancho Janal land bought by E. S. Babcock. It failed in January 1916 after heavy rain, sending a flood 20 to 100 feet high down the Otay Valley that killed more than 14 people. The present arch-gravity Savage Dam, completed in 1918, was named in 1934 for city engineer Hiram Newton Savage.

The reservoir lies on land that was part of Rancho Janal and later Rancho Otay. A hunting lodge at the lake hosted guests of the Hotel del Coronado, and in 1936 Stephen Birch bought the surrounding land; his daughter Mary moved into the former lodge on Upper Otay Lake after marrying a former Royal Air Force commander.

The water is open for multiple activities: fishing with a license, boating with rental options, and picnicking at designated areas. Fires, camping, and dogs on boats are not permitted to keep the water clean and safe.

In February 2009 a bass fisherman spotted a Curtiss SB2C Helldiver in the water; the plane had made an emergency landing on May 28, 1945, during a practice bombing run from a nearby aircraft carrier. Divers examined it in July 2009 and it was raised on August 20, 2010.