Concho River, W Texas, formed at San Angelo by North Concho and Middle Concho rivers, flows c.55 mi/89 km generally E to the Colorado R. (forms L. O.H. Ivie), 18 mi/29 km SE of Ballinger. L. Nasworthy (capacity 10,500 acre-ft.; municipal water supply) is impounded by dam at confluence of the Middle and South Concho just SW of San Angelo. Twin Buttes Reservoir is actually 2 reservoirs, upstream from L. Nasworthy, on both South and Middle branches, joined by narrow channels.
