The Hassayampa area includes about 1,300 square miles in west-central Arizona. The area consists of basins filled with alluvial deposits and mountains composed of crystalline and consolidated sedimentary rocks. The main water-bearing unit is the alluvial deposits, which consist of gravel, sand, silt, and clay. Other water-bearing units consist of crystalline and consolidated sedimentary rocks that may yield a few gallons per minute. In 1978 about 3,000 acre-feet of ground water was withdrawn from the area. Information shown on the maps includes depth to water, altitude of the water level, well depth, specific conductance, and fluoride concentration. Scale 1:125 ,000. (USGS)