Crowley Lake is a reservoir on the upper Owens River in southern Mono County, California, in the United States. Crowley Lake is 15 mi south of Mammoth Lakes. The lake was created in 1941 by the building of the Long Valley Dam by the Los Angeles Department of Water and Power, as storage for the Los Angeles Aqueduct and for flood control. The dam …Crowley Lake is a reservoir on the upper Owens River in southern Mono County, California, in the United States. Crowley Lake is 15 mi south of Mammoth Lakes. The lake was created in 1941 by the building of the Long Valley Dam by the Los Angeles Department of Water and Power, as storage for the Los Angeles Aqueduct and for flood control. The dam is 126 ft high and impounds 183,465 acre⋅ft. For more on the history of the lake, see Owens Lake.