Hydrology of area 28, Eastern Region, Interior Coal Province, Illinois

Abstract

The Eastern Region of the Interior Coal Province is divided into 11 hydrologic reporting areas. Area 28 is located in central Illinois and includes all of the Sangamon River drainage, an area of 5,419 square miles. The southwestern half of the area lies in the Springfield Plain and the northeastern half lies in the Bloomington Ridged Plain physiographic divisions. The entire area is covered with glacial till with a blanket of loess 5 to 10 feet thick on the surface. Pennsylvania rocks with layers of sandstone, limestone, siltstone, shale, clay, and coal underlie about 90% of Area 28, Herrin (No. 6), Harrisburg-Springfield (No. 5), Colchester (No. 2), and Danville (No. 7) coals have been mined in the area. Streamflow and water quality data are collected at a network of hydrologic monitoring stations operated by the US Geological survey. Streamflow can be estimated at ungaged sites. Water quality was analyzed for specific conductance, pH, alkalinity, dissolved sulfate, total recoverable and dissolved iron and manganese, dissolved solids, and other properties. Groundwater is obtained from unconsolidated materials in almost all of Area 28. 39 refs., 54 figs., 18 tabs.