From The Changing Illinois Environment: Critical Trends, 1994, Summary Report of the Critical Trends Assessment Project

The land--bedrock and soil--is a vital aspect of all Illinois ecosystems. The type and extent of wetlands in the state, the depth and quality of its agricultural soils, its commercial mineral deposits--all result from geologic and climatic processes. Just as the wealth of the land has shaped Illinois' economy, human competition for that wealth has shaped its politics and social life. (Figure 4-1 )


While Illinois is not generally thought of as a mining state, it ranks fifth in the nation in coal production and first in the production of fluorspar and silica. Illinois also produces large amounts of aggregates (sands and gravels) essential to the building industry.

Coal. Illinois coals are mostly of the "soft" or bituminous type, found in thick, flat-lying, easy-to-mine beds. These coals have a fairly high heat value, and commonly contain sulfur compounds that have made their use problematic since the advent of federal clean-air rules. Deposits with high development potential have been conservatively estimated at 50 billion tons--enough to yield 25-30 billion tons of usable coal, which is enough to last hundreds of years at present consumption levels.

Coal has been mined commercially in Illinois since the early 1800s. (Figure 4-2 ) Annual production varies with larger trends in the economy, competition from newer fields in other states, changes in industrial and transportation technology (including the use of other fuels), and (most recently) federal regulations. During World War II Illinois mines boomed as they dug a record output of 78 million tons a year; since then production has leveled off at around 60 million tons per year. (Figure 4-3)

Figure 4-3. Trends in Coal Production in Illinois

Source: Earth Resources, Illinois State Geological Survey, ;1994

The method used to mine coal affects the landscape as does the amount of coal mined. The collapse, or subsidence, of underground mined-out "room and pillar" mines can create hard-to-drain wet spots in farm fields. Since 1983, regulations require that such damage be repaired.

More efficient longwall mining removes all the coal in an underground "panel," after which uniform, controlled subsidence takes place according to an approved plan. This predictability makes it easier to protect surface structures and mitigate damage to land.

Some 0.8% of Illinois land--256,000 acres, most of it farmland--has been affected by the strip mining of coal. The state's first, now rather rudimentary, reclamation requirements went into effect in 1962. Of the nearly 153,000 acres of land mined for coal since then, nearly 108,000 acres have been reclaimed to some productive use. In addition, approximately 21,000 acres of land disturbed by mining and abandoned prior to the 1977 federal reclamation laws were covered by mine wastes of various types. Some of these sites are small in size, while others are as large as 300 acres. Some 8,600 abandoned acres have been reclaimed from these so-called "pre-law" sites and another 9,000 acres are considered to need reclamation. (Figure 4-4) Such pre-law land can sometimes be reclaimed for crop production; when feasible, other sites have been reused as vacation home sites, hunting and fishing clubs, and state parks.

Figure 4-4. Coal Production vs. Reclamation

Source: Earth Resources, Illinois State Geological Survey, 1994

Other ore minerals. Illinois land also yields building materials such as sand and gravel; stone used in the manufacture of cement and agricultural lime as well as for ballast and construction aggregates; industrial ores such as silica, clay, and shale; and metallic ores such as lead, zinc, and fluorite, Illinois' official state mineral.

In all, noncoal mining has disturbed about 35,000 acres of land in Illinois. These mines tend to affect only small amounts of land--less than 20 acres over the lifetime of most operations. Some stone quarries leave pits as much as 200 feet deep; some are suitable for lakes, while others must be fenced off for safety reasons, being too large to be filled in. Noncoal mining typically produces fine-grained clays and silts that are slurried into ponds that occupy only about 500 acres statewide; such mining also produces piles of displaced overburden that are typically graded to a gentler slope and planted in grass or trees.

More than half of the sand and gravel produced in Illinois comes from the six northeasternmost counties, where both deposits and demand are large. Nuisance complaints, rather than pollution, are the main problem associated with these sites, many of which have become surrounded by urban development.

Petroleum. Petroleum has been pumped from Illinois wells since the turn of the century. Some 6,700 oil fields draw crude oil from rocks of Pennsylvanian and Mississippian ages and older, mainly in the southern counties. Oil production hit a peak of about 148 million barrels in 1940 and declined to 19 million barrels in 1991.

At present Illinois consumes vastly more oil than it produces, importing 90% from sources outside the state. Most of Illinois' 34,000 wells are small, "stripper wells" that yield as little as two barrels a day. Secondary recovery operations require that water be pumped in large volumes into depleted oil-bearing rocks to force the remaining oil to nearby wells. The process can use as many as 40 gallons of water for every one barrel of oil thus recovered. Most of that water is "produced water" or salt-laden water that has been brought to the surface, separated from the oil, and re-injected, almost always immediately.


Solid wastes. Recorded land waste sites in Illinois number in the thousands. (Figure 4-5 ) Illinois first began to regulate the siting and operation of sanitary landfills in 1973. Though far superior to open dumps, even sanitary landfills may pose some risks to nearby land, mainly from leachate, liquids contaminated as they percolate through fill.

Estimates of the solid waste generated per person in Illinois range from 4.7 to 7 pounds per day. Household and municipal waste amounts have risen generally since 1988, peaking in 1991. Illinois is very dependent on landfills for the disposal of the approximately twelve million tons of solid waste generated annually in recent years. The Illinois Solid Waste Management Act of 1986 was intended to reduce that dependence on land disposal.

Over the past 25 years the risk of contamination to Illinois land and groundwater by operating landfills has been steadily reduced, but the risk from both past and present landfills remains. A survey of landfill sites found that nearly 5% of Illinois' public lands (such as parks and nature preserves), 8% of its wetland and deep water habitat, and nearly 5% of its floodable land are within a mile of a known waste site.

Illinois regulations governing landfills are complex. Different standards for construction, operating, and monitoring are required for on-site and off-site landfills depending on which of several categories of wastes they contain. In general, reviews of permit applications require consideration of the effect a proposed landfill might have on adjacent lands, including floodplains and natural areas; they also mandate engineered systems to prevent contamination of groundwater and surface water. (The ability of a leachate to migrate off-site varies with the hydrology and geology of a particular landfill and the design of the engineered system.)

By 1992 only 106 solid waste landfills were operating in Illinois, and by 1993 the number had dwindled to 64. The dramatic drop in the number of solid waste landfills in the state is thought to have been induced in part by economies of scale, since only larger landfills generate enough in fees to pay for the pollution controls now required of them. More and more materials are no longer landfilled at all, either because of landfill capacity limits (such as yard wastes) or because the materials are environmentally problematic (such as lead-acid batteries).

Though fewer in number, Illinois sanitary landfills are getting larger, so that net capacity statewide actually increased since the mid-1980s. Transition regulations require the disposal of some wastes by means other than landfilling over the short term, while recycling and waste prevention are expected, over the long term, to cause waste streams to dwindle further. Because of such diversions, the shortages of landfill space predicted to occur in the early 1990s have not occurred.

However, not all wastes are regulated, and not all regulations are as stringent as those that govern the operation of sanitary landfills.

Industrial solid wastes. A portion of the materials now going into Illinois municipal landfills are industrial solid wastes, including officially defined industrial process wastes. Their potential for harm is unknown, although some of these wastes may not prove to be "hazardous" under analysis.

Hazardous wastes. According to federally-mandated reports of releases of common toxic industrial chemicals, a relatively small portion of the toxic chemicals released in Illinois in 1990 (less than 7%) was released onto the land. That still amounted to 15.4 million pounds, most of which was composed of metals such as zinc, manganese, lead, and chromium and their compounds.

Recent regulations require that landfills accepting hazardous wastes be equipped with groundwater monitoring wells, impermeable liners, and leachate collection systems; the new rules are reducing the risk that such fills will adversely affect Illinois groundwater. In any event, officially defined hazardous wastes are landfilled in much smaller volumes than is ordinary garbage or municipal solid waste (MSW). Hazardous wastes landfilled in 1990 amounted to less than 2% of the volume of MSW landfilled; the capacity of hazardous waste landfills is not expected to be stretched to its limit until after the turn of the century, based on current rates of generation and disposal.

As of 1990, the number of old potentially hazardous waste sites that qualified for inclusion on state and federal lists of "remediation" or cleanup sites was nearly 1,500. Not all such sites have been investigated; there are at least 1,500 coal gasification plants that generated tars and other toxic byproducts in the late 19th and early 20th centuries. Cleanup of even known waste-contaminated sites has been slow, dogged by money shortages, legal challenges, and technical problems.

The past pollution of Illinois land has economic as well as health effects. The pollution of former industrial sites poses real barriers to the redevelopment of now-abandoned land in Illinois' older cities, since current owners are now liable under federal law for the cleanup of land polluted by former owners.

Radioactive wastes. Well over half the electricity generated in Illinois is produced by plants fired by nuclear fuel. Highly radioactive waste materials from these reactors are stored on-site, although a federal mandate requires the U.S. Department of Energy to dispose of such high-level waste by 1998. As of 1993, low-level radioactive waste from Illinois nuclear-powered plants was shipped to South Carolina for disposal, but Illinois has entered into an agreement with Kentucky to build a facility in which the two states will dispose of such wastes.

Measured by five-year averages, volumes of low-level radioactive waste shipped from power plants have declined since the mid-1970s by some 17%, presumably because of changes in treatment or production processes at electricity plants. However, the radioactivity of that waste (as measured in curies) increased dramatically from 1974 to 1991, rising by more than 9500% to 41,000 curies.

Liquid wastes. Liquid wastes from industrial processes are often temporarily stored or treated atop the land in tanks or impoundments (sometimes called pits, ponds, or lagoons). This technique allows liquids to be evaporated, or solid wastes to be concentrated, prior to disposal by other means.

An IEPA survey in 1980 counted 7,450 active or abandoned waste impoundments in Illinois. Unlined or improperly lined impoundments are considered by some authorities to be the most significant source of chemical pollution of Illinois groundwater. More than a quarter of the surface impoundments in Illinois are thought to be in places where near-surface geology leaves subsurface soils prone to infiltration; surface soils also may be contaminated when impoundments accidentally overflow.

It is not clear how many waste impoundments are in use today, but tighter regulations are making the practice of storing officially designated hazardous wastes on land less attractive. A 1983 estimate by the Illinois Environmental Protection Agency put the number of on-site storage impoundments at 150; by 1986 only 27 reportedly were still in use.

Mining wastes. At sites where coal was processed at the surface, piles of "gob" or leftovers from the separation of coal from rock and other impurities can occupy large tracts of land. Slurry ponds contain very fine-grained clay and minerals cleaned from coal. Pyrite grains (iron sulfide) that occur in most Illinois coals may react with moisture and air at the surface, creating acid drainage that may contaminate nearby streams. Untended gob piles and dried-out slurry ponds are a source of airborne pollutants, and erosion from unstable piles can clog drainage ditches and flood nearby farm fields.

Miscellaneous. Illinois land is used to dispose of assorted organic matter, mainly agricultural wastes such as crop residues and animal manures. Farm land also is the preferred site for the disposal of sludge from publicly-owned sewage treatment works and certain cannery wastes generated by commercial food processors. Most of the former are small works, located in rural areas with immediate access to large amounts of land.

There also is a trend toward land storage and disposal of nonhazardous sludges. Many Illinois towns and villages, for example, use surface pits to dry sewage sludge before trucking it to landfills. More than 12% of the amount of sludge that was landfilled in 1989 was land-applied in 1991, in part because of state landfill regulations that encourage the latter practice. However, those regulations also strictly limit the amount of toxic metals that may be taken up from the soil and incorporated into food crops; as a result, land disposal is not an option for Illinois' biggest publicly owned treatment works, whose sludge contains residues of factory wastes.


Urbanization is a well-remarked trend nationwide. In 1860, 86% of Illinoisans lived outside of cities. By the turn of the present century, as many people lived in urban as in rural areas; by 1990, 85% of Illinoisans lived in urban areas. (Figure 4-6)

Figure 4-6. Illinois Population 1810-1990

Source: Sources of Environmental Stress, ENR Office of Research and Planning, 1994

The automobile and the truck are accelerating the movement of 20th century Illinoisans into what the U.S. Census defines as "urbanized areas" on the fringes of cities. Beginning around 1960, Illinois' urban fringe grew so rapidly that by 1990 it housed 37% of the state's population--as many people as lived in central cities at that time. (Figure 4-7)

Figure 4-7. Population Distribution 1960-1990

Source: Sources of Environmental Stress, ENR Office of Research and Planning, 1994

Much of Illinois' recent population growth is centered in the northeast. The Northeastern Illinois Planning Commission estimates that between 1970 and 1990 the population of the city's six Collar Counties grew by 4%, while the amount of urbanized land expanded by 51%--a net land consumption over the two decades of more than 360,000 acres. These are not trends unique to Illinois; indeed, urban sprawl was somewhat later in arriving here than in boom states of the East and the Sunbelt.

Unnatural Selection | Forests

Return to Table of Contents