Abstract: Hydrologic data are being collected in four basins in the Warrior coal field to provide baseline information to aid in determining the effect mining will have on water resource Basins monitored are in two different geologic and hydrologic environments. Well yields from the Pottsville Formation generally range from 0 to 0.3 L/s, whereas well yields from the Coker Formation generally range from 0.3 L/s to 6.4 L/s. Streamflow distribute reflects seasonal precipitation. Streams draining basins underlain chiefly by the Pottsville Formation frequently go dry, whereas those draining basins underlain chiefly by the Coker Formation have well sustained low flows. Water in the Pottsville Formation is slightly acidic and moderately hard to very hard. Dissolved solids concentrations ranged from 176 to 268 mg/L. Water in the Coker Formation is soft, far less mineralized and more acidic than water in the Pottsville. Surface water is generally soft, acidic, and low in dissolved solids concentrations. Water in streams draining basins underlain chiefly by the Pottsville Formation was slightly more mineralized and less acidic than water in streams draining the Coker Formation.