From The Changing Illinois Environment: Critical Trends, Volume 2: Water Resources , Technical Report of the Critical Trends Assessment Project


Environmental issues related to water in the state of Illinois have been discussed and written about for more than a century. Erosion, sedimentation, water use, flood control, water quality, and water pollution have been major concerns for decades. Many state and federal agencies involved in resource planning have worked jointly on various planning commissions, task forces, and committees and have prepared numerous reports describing threats to the quality of the environment, the health and well-being of the people of the state, and the adequacy of the water supply. Water For Illinois - A Plan For Action (Office of the Governor, 1967) is a good example.

As discussed in the Report of the Illinois State Fish Commissioner (1899), one of the most frequent complaints reaching the commission was water pollution due to the waste from gas factories, paper mills, etc., entering several points along the Fox, Des Plaines, and Illinois Rivers. The destruction of fish due to these discharges was great. The Illinois State Board of Health's Report of the Sanitary Investigations of the Illinois River and Its Tributaries (1901) stated that "due to the sewage of Chicago being dumped into a stretch of the Chicago River from its mouth to a point past Bridgeport, the river was a seething, festering mass of decomposing sewage from house and factory, giving up great quantities of noisome gases; the surface of the river in many places having the appearance of a boiling caldron. Below Peoria, the river banks were strewn with dead fish due to the washings of the cattle barns at Peoria."

The effect of point and nonpoint pollution on surface and groundwater quality has been a continuing problem for decades (Illinois State Water Plan Task Force, 1984). The Illinois Environmental Protection Agency reported that since 1979, several Illinois rivers and streams have shown improving trends in general water quality, including the Illinois and Mississippi Rivers, and the Rock River (IEPA, 1990). The major causes of continuing water quality problems are siltation, nutrients, habitat/flow alteration, organic enrichments/dissolved oxygen, ammonia, metals, and suspended solids. Streamflow conditions and the amount of withdrawals from the state's streams are of major concern because of the impact on water quality, transportation, and availability for downstream users (State Water Plan Task Force, 1992b).

Groundwater monitoring and assessment information to date indicate that statewide groundwater quality is generally good. However, many activities, past and present, contribute to groundwater contamination in Illinois (IEPA, 1992). Major sources of identified contamination include leaking underground gasoline storage tanks, large quantities of above-ground petro- leum storage, agricultural chemical operations, salt piles, landfills, and treatment storage/disposal units. New approaches to defining and solving the point and nonpoint pollution problems of the state are an ongoing process (State Water Plan Task Force, 1992a).

Sediment in Illinois streams is recognized as the number one pollution problem in the surface waters of the state (Bhowmik, 1986). Erosion and sedimentation impact many agencies and businesses in addition to being very destructive to the land, lakes, and waterways of the state (ISWS, 1952). Sediment is very costly to remove from drainageways and lakes (Fitzpatrick et al., 1987). Many reaches of Illinois' commercially navigable rivers require dredging on a continuing basis so that barge traffic can be kept moving and profitable (IDOT, 1988). More than 1,700 drainage districts in the state require periodic maintenance to remove silt at a cost of millions of dollars.

The Illinois State Water Plan Task Force (1984) also listed erosion and sediment control at the top of the list of critical issues. Many biologists believe that sediment is the most destructive factor in the aquatic component of the ecosystem. Sediment transport and deposition have a major impact on the aquatic habitat of lakes and streams. Public drinking water utilities spend large sums of money on water treatment to reduce turbidity and sedimention levels. Sedimentation also causes large annual losses of reservoir capacity in more than 100 Illinois instream or side-channel impoundments.

Water use, water conservation, and droughts (ISWS, 1952; Office of the Governor, 1967; Illinois State Water Plan Task Force, 1984) have been a major concern in portions of the state since the droughts of the 1930s. Although ground water is a major resource in northern Illinois, excessive drawdown of the groundwater level has occurred in portions of northeastern Illinois since the 1920s (Office of the Governor, 1967). Because the interior southern half of the state of Illinois has very limited groundwater resources, major public surface water districts have been established in the areas of Kinkaid Reeds Creek, Carbondale, Kaskaskia, and Rend Lake. More than 90 public water supply lakes in Illinois serve major communities such as Springfield, Decatur, Danville, Taylorville, Bloomington, and Carbondale. The cost of potable water varies widely over the state due to the cost of availability, treatment, and distribution.

As the state population grew and people began to live and work in the lowlands, flooding and flood control became important issues. Losses due to flooding run into millions of dollars each year. Reports documenting the numerous floods during the period 1904 through the early 1940s (Alvord and Burdick, 1919; Mulvihill and Cornish, 1929; Illinois Department of Public Works and Buildings, 1946) along with the State Water Plans of 1967 and 1984 (Office of the Governor, 1967; Illinois State Water Plan Task Force, 1984) point to the fact that flooding and flood control continue to be critical issues. A number of more urbanized areas of the state have established stormwater management districts for improving flood control and reducing losses due to flooding.

Since the mid to late 1980s, there has been growing national concern over groundwater contamination and its potential impacts on those individuals who rely on this resource for their drinking water. This concern has led to the initiation of several laws and agency policy shifts to help ward off this imposing threat or to help create a monetary base for research and remediation of existing contamination. Illinois is one of only a handful of states that has adopted legislation in an attempt to respond to this concern. In 1987, the Illinois Groundwater Protection Act (P.A. 85-0863) was passed as a comprehensive, prevention based approach focused upon beneficial uses of ground water and preventing degradation. This act relies on state and local partnership and, although directed toward protection of ground water as a natural and public resource, it specifically targets drinking water wells in Illinois. This and many other legislative initiatives have set the tone for environmental protection throughout the entire nation. It has become apparent that the concern for our natural resources is a high priority, and the detailed analysis of degenerative trends of these resources may open the opportunity to develop management practices to help secure a safe and protected environment.


Illinois has an abundant supply of surface water within its borders. Unfortunately, these waters are unevenly distributed throughout the state. In a sense, Illinois is almost an island with fresh water surrounding its interior. Its western border consists of the Mississippi River, the southern and southeastern borders are defined by the Ohio and Wabash Rivers, respectively, and Lake Michigan borders it to the northeast. These are not the only sources of fresh surface water to Illinois. Its interior is crossed with large supplies of available water from major rivers such as the Illinois, the Rock, the Kankakee, and the Kaskaskia, as well as numerous other smaller rivers and streams.

Illinois also has abundant buried groundwater reserves. Major aquifer units supply millions of gallons per day for public and industrial use in Illinois. These aquifers are also unevenly distributed throughout Illinois. However, in most cases, where one resource is unavailable, the other or a combination of the two will be available for the required need. The distribution of these resources is detailed in figures 1 and 2. This chapter describes the environmental issues and concerns associated with these resources in Illinois.

This report examines environmental issues related to hydrologic processes in Illinois. It concentrates on those issues deemed of major concern in regard to surface and groundwater resources. Each chapter of the report describes historic information and possible trends over time, allowing a critical review of the state of the particular resource. This review is a combination of many sources of information and can aid in our understanding and potential management of these resources. The ongoing compilation and collection of these data are essential to this understanding and must be recognized as a valuable resource to the people of Illinois that merits continuing support.


Alvord, J.W., and C.B. Burdick. 1919. Rivers and Lakes Commission Report on the Illinois River and Its Bottom Lands. Illinois Department of Public Works and Buildings, Division of Waterways.

Bhowmik, N.G., J.R. Adams, A.P. Bonini, A.M. Klock, and Misganaw Demissie. 1986. Sediment Loads of Illinois Streams and Rivers. Illinois State Water Survey Report of Investigation 106, Cham-paign, IL.

Fitzpatrick, W.P., W.C. Bogner, and N.G. Bhowmik. 1987. Sedimentation and Hydrologic Processes in Lake Decatur and Its Watershed. Illinois State Water Survey Report of Investigation 107, Champaign, IL.

Illinois Department of Public Works and Buildings and the U.S. Department of the Interior Geological Survey. 1946. The Floods of May 1943 in Illinois. Division of Waterways.

Illinois Department of Transportation, Division of Water Resources (IDOT). 1988. Directory of Lake and River Terminals in Illinois.

Illinois Environmental Protection Agency (IEPA). 1990. Illinois Water Quality Report 1988-1989.

Illinois Environmental Protection Agency (IEPA). 1992. Illinois Water Quality Report 1990-1991.

Illinois State Board of Health. 1901. Report of the Sanitary Investigations of the Illinois River and Its Tributaries. Phillips Bros., State Printers, Springfield, IL. Illinois State Water Survey. 1952. Proceedings of the Conference on Water Resources, October 1-3, 1951. Illinois State Water Survey Bulletin 41, Cham-paign, IL.

Illinois State Water Plan Task Force. 1984. Illinois State Water Plan: Critical Issues, Cross-Cutting Topics, Operating Issues.

Illinois State Water Plan Task Force. 1992a. Memorandum and Draft Document, IEPA Watershed Document.

Illinois State Water Plan Task Force. 1992b. Memorandum and Draft Document, Remaining Issues and Implementation Requirement.

Mulvihill, W.F., and L.D. Cornish. 1929. Flood Control Report: An Engineering Study of the Flood Situation in the State of Illinois. Division of Waterways.

Office of the Governor. 1967. Water for Illinois --A Plan of Action.

Report of the Illinois State Fish Commissioner from October 1, 1896, to September 30, 1898. 1899. Phillips Bros., State Printers, Springfield, IL.

Figure 1. Surface water resources of Illinois

Figure 2. Principal aquifers in Illinois

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