Twin Buttes Dam is a 134-foot-high zoned earthfill structure with a crest of 30 feet and a crest length of over 8 miles. The embankment contains 21,465,854 cubic yards of material. An equalizing channel with a bottom width of 250 feet was excavated between the South Concho River and Spring Creek drainage areas. The outlet works for the dam, located near the left abutment, include an approach channel from the Middle Concho River, a concrete intake structure, 3-barreled concrete conduit with gate chambe and shaft, chute, and stilling basin. The spillway structure, also near the left abutment, is an uncontrolled ogee weir 200 feet in width. A concrete chute section, 320 feet long, extends from the crest to a stilling basin. Water from the stilling basins of both the spillway and outlet works discharges into a common channel.
Twin Buttes Reservoir has a total capacity of 640,580 acre-feet with a surface area of 23,508 acres. Active capacity of the reservoir is 632,210 acre-feet.