Ground water is an important source of water supply in Illinois.
About 2.5 million people in Illinois are supplied from ground-water resources. Total ground-water withdrawls in the State was approximately 953 million gallons per day in 1995. Tens of thousands of persons in the State rely on ground water from residential wells as their sole source of water. Ground-water quality is a major concern in Illinois. Water-quality degradation or contamination results from point and nonpoint sources throughout the State.