Ground-water levels in the American Bottoms regions around East St. Louis, Illinois, have risen several feet since the early 1970's. Artificial dewatering of the aquifer by increased pumping is being investigated by the U.S. Army Corps of Engineers to alleviate economic and health concerns resulting from elevated ground-water levels. A ground-water quality evaluation is necessary for selecting a feasible dewatering scheme. Analyses of water samples from 63 wells show that except for iron, manganese, and dissolved solids, constituent concentrations do not exceed Illinois water-quality standards. The waters are primarily of the calcium-magnesium-bicarbonate type with some calcium-sulfate type water. Iron concentrations ranged from less than 3 to 82,000 micrograms per liter, manganese from 5 to 5,300 micrograms per liter, and dissolved solids from 140 to 3,000 milligrams per liter. These constituent concentrations exceed Illinois ' public water supply, effluent, and general water-quality standards in most samples and analysis indicates the concentrations are representative of the ambient water quality. Concentrations of nitrite + nitrate nitrogen fluoride, zinc, lead, and sulfate also exceeded Illinois water-quality standards in a few samples. Concentrations of organic pesticides, polychlorinated biphenyls, and polychlorinated naphthalenes were below analytical detection limits.
