Illinois Water Supply Planning


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Surface Water Use and Water QualityBack
There is a clear relationship between water use and water quality. The quality of water varies regionally and by water source. Surface waters serve the dual role of supply source and receptors of treated wastewater (point source pollution). Surface waters are also susceptible to nonpoint source pollution, including elevated nutrient loading and pathogens that impair water use for human consumption. Consequently, sediments and other suspended materials must be filtered from surface waters, nitrate levels must be reduced below 10 milligrams per liter (health standard), water must be treated chemically for bacteria, and presence of certain pathogens requires advanced treatments. The Illinois Pollution Control Board (IPCB) and Illinois Environmental Projection Agency (IEPA) oversee standards and set use attainment criteria for streams and rivers on the basis of their intended use, with the most stringent requirements for waters intended for human consumption. The IEPA Web site contains biennial reports on water quality status of surface water and groundwater in Illinois ( and presents use attainment criteria for streams ( in a map format that can be searched geographically or queried.

Additional information about water quality, permitting, and compliance are available on the U.S. Environmental Protection Agency (USEPA) Envirofacts Web site ( This site contains water information from three USEPA databases: the Permit Compliance System, the Safe Drinking Water Information System, and the National Contaminant Occurrence Database. Permits for discharges may be viewed as well as compliance records of individual public water supplies.

Public water supplies that use surface water must test for a multitude of constituents. The IEPA Web site has information about Illinois’ rules and regulations ( As research continues about the effects of various chemicals and pharmaceuticals found in surface water, additional compliance monitoring may be mandated. While essential for the quality and safety of drinking water, compliance testing is expensive, as is treatment. As waste loads to surface waters increase, these costs rise even further.


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