The study design for ground water focuses on the assessment of water-quality conditions of major aquifers in each study unit with emphasis on the quality of recently recharged ground water associated with present and recent human activities. Ground-water quality is determined primarily by chemical characteristics that tend to vary more spatially than temporally, making spatial characterization a a main focus in ground-water assessment. The initial emphasis is on the chemical characteristics of ground water.
Major ground-water quality issues in the Lower Illinois River Basin include nutrients and agricultural chemicals, and trace elements. The Illinois River is a primary channel for the transport and disposal of much of the State's human, animal, industrial, and agricultural wastes. Alluvial aquifers underlying the Illinois River supply large amounts of drinking water. Contaminants in the river can move into the alluvium and into the water-supply wells. Also, the major bedrock valley aquifers are hydraulically connected to the Illinois River alluvium. Withdrawals from these buried aquifers can potentially draw in contaminated river water.
Results from recent statewide studies indicated that concentrations of
nitrate and other agricultural chemicals exceeded maximum contaminant
levels (MCLs) for drinking water in surface- and ground-water supplies. In
1990, about 9-million pounds of atrazine were applied in Illinois, nearly
one-sixth of the national total and more than any other State. Results
from several recent studies of ground-water quality in public-supply wells
throughout Illinois have indicated concentrations of nitrate, pesticides,
and volatile organic compounds above MCLs for safe drinking water.
Personnel to contact about a specific subject are listed on the staff page.
U.S. Department of the Interior
U.S. Geological Survey
221 North Broadway, Urbana, IL 61801, USA
Last modified: 11:00 CST Thurs 11 May 2000