Studies of seepage data resulted in a pilot grouting contract which was awarded in June 1976 and completed in March 1977. Subsequent to the grouting, a foundation cutoff wall was installed through a large section of the upstream toe of the dam, between 1996 and 1999. The San Angelo Project brings 15,000 acres of land under irrigation. Because of the severe drought conditions experienced following completion of construction, it was not possible to start irrigating until March 1972, when the development period began. Following the development period, bringing irrigation water to project lands increased the yield per acre and increased the variety of crops that can be grown.
Principal crops are cotton, alfalfa, grain sorghum, oats, pasture, and grain.
Municipal and Industrial Water San Angelo has grown rapidly since 1940 and is the most important population center in the Concho River Basin. The San Angelo Project assures an adequate water supply for the city until the year 2010, based on estimated population growth. The arid, relatively barren nature of the area limits recreation opportunities. Consequently, surface-water impoundments suitable for fish and wildlife and for recreational uses make an important contribution. Twin Buttes Reservoir also allows maintaining Nasworthy Reservoir at a relatively constant level, enhancing its recreation value.