Bed rock in the Stigler area of southeastern Oklahoma consists principally of shale, siltstone, and sandstone of the McAlester, Savanna, and Boggy Formations of Pennsylvanian age. These rocks have been folded to form the Stigler syncline on the north and the Antioch anticline on the south. An area of several square miles is underlain by terrace deposits, mostly sandy silt, as much as 25 feet thick. Alluvium along the streams is 5 to 10 feet thick and consists mainly of sandy silt. Neither the terrace deposits nor the alluvium are hydrologically significant. Water in the bedrock is under artesian conditions. Well depths range from 34 to 235 feet and average 95 feet. The water level in most wells is less than 30 feet below the land surface. Because the rocks have minimal permeability, well yields probably are less than 5 gallons per minute. Much of the area is provided with water by a rural water district. Based on specific-conductance measurements, dissolved-solids concentrations in ground water are estimated to range from 200 to 2,500 milligrams per liter. Nor relationship between variations in specific conductance and well depth, geographic distribution, or geologic formation is apparent. Streams in the area are ephemeral and extended periods of no flow can be expected. During much of the period of record, streamflow in Taloka Creek was maintained by water pumped from an active coal mine. Water upstream from the mine area had a mean dissolved-solids concentration of 72 milligrams per liter whereas water downstream from the mine area had a mean concentration of 1,323 milligrams per liter. At times, downstream concentrations of some toxic metals exceeded the standards for drinking water set by the U.S. Environmental Protection Agency. Samples of water collected from Taloka Creek since mining ceased did not have excessive concentrations of toxic metals. Maximum suspended-sediment discharge of Taloka Creek was about 1,660 tons per day. Silt-clay particles (diameters less than 0.062 millimeter) were the dominant grain size. Observed and measured effects of surface mining for coal on the hydrologic system include (1) creation of additional water storage in the surface mine pond, (2) disruption of drainage in an area of about 1 square mile, and (3) increased mineralization of water in Taloka Creek. Other possible effects include (4) changes in permeability and storage of water in mine spoil, (5) minor changes in streamflow and runoff characteristics, and (6) temporary increase in the sediment load of Taloka Creek.