Olmos Reservoir (San Antonio River Basin)
Olmos Reservoir is located four miles north of San Antonio in Bexar County, on Olmos Creek, a tributary of the San Antonio River. The project is owned and operated by the San Antonio River Authority for flood control. The reservoir was constructed after the record flood of September 1921, which extensively damaged the San Antonio business district. Construction of the dam started in 1925 and was completed in 1926. In March 1979, improvement was made to strengthen and anchor the dam, and modification to the gate operations to provide an emergency spillway. The dam is gravity concrete structure of 1,941 feet long with a maximum height of 60 feet. The reservoir has a capacity of 12,600 acre-feet and a surface area of 889 acres at the top of flood control pool of 725 feet above mean sea level. The drainage area above the dam is 32 square miles.