University of Illinois at Urbana-Champaign. Water Resources Center
Abstract
The chemical analyses of waters from 67 Illinois streams have produced data which, when weighted according to discharge magnitudes and the frequency with which those magnitudes are equaled or exceeded, permit an estimation of the frequency-weighted mean concentration (mg/l ) and the long term yield (tons/sq mi/yr), during the period 1945-1971. Most of the measured constituents have concentrations and yields which display regional patterns, expressed in simple contour patterns. The magnitudes and patterns of the contours indicate, in most cases, variations in geologic, hydrologic, and/or demographic conditions. Anomalous contours may reveal anthropogenic influences, such as strip mining, use of fertilizers, waste disposal, street salting, and washout of aerosols from the atmosphere.U.S. Department of the InteriorU.S. Geological SurveyOpe
