There are 3,041 lakes in Illinois and more than 87,000 ponds.
Lakes serve as traps for materials generated within their watersheds.
The trapped material generally impairs water quality and may severely impact beneficial uses and significantly shorten the life of the lake. Suspended and deposited sediments can cause serious use impairment problems. An overabundance of plant life may tend to limit recreational and public water supply usage. Lakes may also collect heavy metal and organic contamination from urban, industrial, and agricultural sources. Dissolved oxygen deficiencies may limit biological habitat, or result in taste and odor problems for public water supplies.