Geohydrology and susceptibility of Coldwater Spring and Jacksonville fault areas to surface contamination in Calhoun County, Alabama

Coldwater Spring in eastern Calhoun County, Alabama, is one of the largest springs in Alabama. The spring, which has an average discharge of about 31 million gallons per day, supplies water for about 70,000 people in the Anniston, Alabama area. A potentiometric map of the study area indicates that the recharge area for the aquifer system that supplies the spring is only about 23 square miles. However, base-flow data for streams in the area indicate that this recharge area is not sufficient to account for an average discharge of 31 million gallons per day from Coldwater Spring. Complex folding and faulting of the carbonate and quart zitic rocks that comprise the aquifer system may have produced fractures and joints that increase recharge to the spring. Some recharge to the spring may be derived from outside the recharge area delineated from the potentiometric map or from the surface. This part of the recharge area contamination from the surface. This part of the recharge area consists of flat to gently rolling terrain underlain by cavernous limestone and fractured quartzite. (USGS)