“Susceptibility of Groundwater to Pollutants” is defined here as the ease with which a contaminant can be transported from the land surface to the top of the groundwater called the “water table”. Many materials that overlie the groundwater offer good protection from contaminants that might be transported by infiltrating waters. The amount of protection offered by the overlying material varies, however, depending on the materials. Thus, in some areas, the overlying soil and bedrock materials allow contaminants to reach the groundwater more easily than in other areas of the state. 

In order to identify areas sensitive to contamination, the Wisconsin Department of Natural Resources, in cooperation with the University of Wisconsin-Extension, Wisconsin Geological and Natural History Survey and the USGS, has evaluated the physical resource characteristics that influence this sensitivity.

Five physical resource characteristics were identified as important in determining how easily a contaminant can be carried through overlying materials to the groundwater. These characteristics are depth to bedrock, type of bedrock, soil characteristics, depth to water table and characteristics of surficial deposits. Existing statewide maps of these five characteristics were used whenever possible. New maps were compiled when existing information wasn’t already mapped. The resource characteristic maps used in this project were compiled from generalized maps at a scale of 1:250,000 or 1:500,000.

Each of the five resource characteristic maps was put into digital form using a Geographic Information Systems (GIS) program. All of the information contained in the five maps were overlaid and combined into one composite map. A numeric rating scheme developed for each map was used to score the maps and the five resource map scores were added together within GIS. The composite map shows the scores for each area – low scores represent areas that are more susceptible to contamination and high scores represent areas that are less susceptible to contamination.

The method described above is a subjective rating method; specifically an index method. An index method assigns a subjective ratings or score to physical resource characteristics of an area to develop a range of contamination susceptibility categories (ranging, in this case, from more susceptible to less susceptible). Index methods are fairly popular approaches to groundwater susceptibility, because they are quick and straightforward, and they use data that are readily available. However, the mapped distribution of susceptibility categories produced by an index method is typically fraught with uncertainty, primarily due to the subjectivity in the approach. The susceptibility categories include little quantifiable or statistical information on uncertainty and this limits their use for defensible decision making. So while susceptibility maps produced using index methods can be useful, their inherent uncertainty must be kept in mind. (National Research Council, 1993^E1; Focazio and others, 2002^E2).

Human health is the primary reason high levels of nitrate in drinking water are of concern.^F3 Nitrate can cause a condition called methemoglobinemia, or “blue-baby syndrome,” in infants under six months of age. Nitrate in water used to make baby formula converts to nitrite in the child’s stomach and changes the hemoglobin in blood to methemoglobin. The infant’s body is then deprived of oxygen. In extreme cases, methemoglobinemia can be fatal; the long-term effects of lower-level oxygen deprivation are unknown.

The conversion of nitrate to nitrite in the human body also creates N-nitroso compounds, which are some of the strongest carcinogens known. As a result, additional human health concerns linked to nitrate-contaminated drinking water include increased risk of non-Hodgkin’s lymphoma^F8, gastric cancer^{F9, E10}, and bladder and ovarian cancer in older women.^F11 There is also growing evidence of a correlation between nitrate and diabetes in children.^{F12, E13} The current drinking water limit of 10 mg/L for nitrate-nitrogen addresses only methemoglobinemia; the concentration at which cancer risks occur is unknown.

Nitrate also affects surface water ecosystems by increasing the growth of nuisance algae that then die and deplete the water of oxygen. Between the late 1960s and the early 1980s, nitrate levels in waters flowing into the Gulf of Mexico more than doubled, causing a “dead zone” that in 1999 was approximately the size of the state of New Jersey.^F14 In Wisconsin, the effects of increasing nitrate levels in surface waters are mostly unstudied.

Because of the health concerns, public water supplies that exceed the 10 mg/L limit are required to reduce the nitrate-nitrogen level. The most common solutions include drilling a new, usually deeper, well; blending contaminated water with non-contaminated water to lower the nitrate concentration; or removing nitrate through water treatment processes. However, such solutions are often costly. By 2006, 25 Wisconsin public drinking water systems had exceeded the nitrate limit and collectively spent over $24 million on remedies. This number is up sharply from just 14 in 1999.^F3 For information about which public drinking water systems exceeded the nitrate limit see Money Spent on Cleanup.

The Wisconsin Well Compensation fund can assist a private well owner if the nitrate level in his or her well exceeds 40 mg/L (four times the human health limit), but only if the well is used for livestock watering. Options for private well owners include replacing or modifying the well, connecting to a public water supply, installing a water treatment system, or using bottled water for cooking and drinking.^F3

Private well water testing and education programs offered by the University of Wisconsin – Extension have been successful in increasing both public awareness of individual nitrate problems and local government officials’ interest in taking proactive planning steps to protect groundwater. In Iowa County, for example, town officials began using groundwater information collected through such programs as criteria for siting new facilities and developments.^F15

Many educational programs have also been put in place to help farmers limit the loss of nitrogen to groundwater. These programs emphasize soil testing and proper crediting of nitrogen sources already in place to avoid overfertilization, and good management practices for fertilizer storage and handling to minimize spills and other losses. However, numerous researchers have shown that in central Wisconsin, such best management practices are not always adequate to prevent contamination of groundwater with nitrate above the drinking water limit.^{F16, E17}

Recent research on Wisconsin farms has shown that cattle raising using management intensive grazing (also known as rotational grazing or grass-fed agriculture) has potential for protecting groundwater from nitrate contamination.^F18 In general, well-managed organic farming practices also lower nitrate inputs to groundwater,^{F19, E20} but at times, leaching from organic systems may also exceed the drinking water limit for nitrate.^F21

Some local governments have been successful with providing incentives to farmers to grow groundwater-friendly crops or otherwise limit nitrogen applications around city wells. For example, the city of Waupaca identified fields in the recharge area for its wells and provided various incentives for farmers to enter into cropping agreements to limit nitrate inputs.^F22 A community may choose to hire a specialist to evaluate nitrate-susceptible areas and develop possible management strategies.

In addition, three rules currently being proposed or implemented could decrease nitrate contamination of groundwater:^F3

• NR243 (finalized and to be promulgated in spring 2007) lowers nitrogen levels reaching groundwater from manure and process wastewater by requiring improved manure storage facilities and prohibiting excessive or improper application of manure and process wastewater on cropped fields. This rule will apply to large Concentrated Animal Feeding Operations of 1000 animal units and larger. Currently, there are about 150 of these permitted operations in Wisconsin.
• ATCP51 (enacted in April 2006) is a livestock siting standard that protects areas susceptible to groundwater pollution. Required standards prevent runoff from entering sinkholes, ensure that existing storage structures do not leak, and require a manure application plan that minimizes risks to groundwater, including existing wells. This adopted rule is expected to apply to about 70 new and expanding farms of more than 500 animal units each year.
• ATCP50 (still pending as of April 2007) applies to all farms and includes the requirement for nutrient management plans by 2008. It incorporates new 2005 USDA NRCS nutrient standards (590 standards) for both nitrogen and phosphorus application.

Some nitrate loss from agricultural activities seems inevitable even with good management practices, especially in areas with coarse-textured soils or shallow soils over fractured bedrock. From a planning perspective, therefore, the solutions may lie in keeping new agricultural operations out of the zone of influence for existing wells, and in avoiding the location of new private or public wells in areas where nitrate contamination in groundwater has already occurred.

The 2002 UW-Extension publication titled “Planning for Natural Resources - A Guide to Including Natural Resources in Local Comprehensive Planning” gives more details about the following implementation tools that can be used to address natural resources issues in the planning process:

1. Education Tool: Education and citizen participation in making land use decisions, implementing land use goals, and taking private actions aimed at limiting nitrate contamination of groundwater.
2. Environmental Assessment Tool: Environmental assessment requirements within zoning or subdivision ordinances to provide detailed information about the potential effects of proposed development on nitrate levels in groundwater, or to ensure that suitable sources of water for private wells are available on a proposed development site.
3. Facility Planning Tool: More detailed facility plans for potential contamination sources, such as spill containment plans for potential nitrate sources.
4. Regulatory Tools, including:
1. Zoning
• Performance zoning, which outlines general water quality goals that developers or other landowners can meet by a variety of methods.
• Overlay zoning, which allows special regulations of sensitive environmental areas such as wellhead protection districts or groundwater recharge areas.
• Planned Unit Developments may allow developers to vary some of the standards in local zoning ordinances to allow innovative approaches that may better protect groundwater.
2. Subdivision regulations could include requirements for adequate and safe water supply and wastewater disposal and treatment facilities, as well as addressing land suitability and environmental and design issues. (For further information on subdivisions’ impacts on groundwater, see footnote #3).
3. Increased nitrate treatment by onsite wastewater systems could be encouraged with financial incentives or density bonus incentives, although the current Wisconsin Administrative Code (Comm 85.035) does not allow such systems to be required.^F23
4. Density transfers can allow the transfer of development rights from one parcel that a community wants to protect to another parcel where the community wants development to occur.
5. Acquisition Tools, including:
1. Outright purchase of land needed for groundwater protection by communities or non-profit conservation organizations.
2. Conservation easements could limit land uses to those not likely to contaminate groundwater with excess nitrate.
3. Purchase of development rights can protect land from development with certain types of groundwater-contaminating activities while allowing the landowner to retain ownership of the land and the ability to sell or transfer it at any time.
4. Eminent domain allows government to take private property for public purposes with compensation to the owner, even without the owner’s consent. This tool could be used to acquire critical groundwater protection areas.
6. Fiscal Tools, including:
1. Capital improvement programs that help a community plan and budget for capital improvements such as water supplies and wastewater treatment facilities.
2. Impact fees can require new developments to pay for improvements needed to serve that development.
3. WDNR may provide grant or loan programs to help communities assess and meet their needs in areas involving sensitive natural resources such as groundwater.

A community could also consider hiring a specialist to evaluate areas where groundwater is particularly vulnerable and to identify agricultural and other strategies to minimize nitrate leaching.

How much of a pesticide application will leach to groundwater depends upon four factors:^F30

• pesticide properties such as high water solubility, low adsorption (the ability of a pesticide to attach to soil particles), and high persistence (how long it takes for the chemical to degrade)
• soil characteristics such as high permeability and porosity, low soil compaction, low amounts of organic material, and high amounts of sand and gravel content
• site conditions such as shallow depth to groundwater, high amount of precipitation, and excessive irrigation
• management practices such as poor timing of pesticide application, not incorporating the pesticide into the soil, poor handling of the chemical, and solely relying on chemicals for pest control

Determining which pesticides are in groundwater at a given location and time is difficult and can be expensive. A pesticide test generally looks for a single chemical, or more commonly, a broad group of chemicals, but not all pesticides are detected by any one test. Pesticides break down over time into metabolites which may not have the same testing method as the parent compound. Further, some pesticides do not have approved testing methods, so they cannot be measured in water.

The health effects of pesticide exposure vary by pesticide. For example, atrazine, a common corn herbicide, has been linked to weight loss, cardiovascular damage, retinal and some muscle degeneration, and cancer when consumed at levels over the drinking water limit for long periods of time.^F31 Long-term exposure to alachlor, another herbicide, is associated with damage to the liver, kidney, spleen, and the lining of the nose and eyelids, and cancer.^F32 Only about 30 pesticides currently have health-based drinking water limits in Wisconsin, so occasionally, pesticides are detected in drinking water, but their harmful levels or health effects are unknown. Also unknown are the health effects of a combination of pesticides in drinking water, even at levels below the drinking water limit for any one of the pesticides.

To learn more about pesticides, please see

• Extension Toxicology Network: includes pesticide trade names, regulatory status, and toxicological and ecological effects
• National Pesticide Information Center: includes how pesticides work, toxicity, metabolites, and environmental effects.

Goals for groundwater protection from pesticides may include:

• Determine what pesticides are being used and where. Test wells in these areas for these pesticides and their metabolites.
• For pesticides with established drinking water limits, keep concentrations below the drinking water limit.
• Encourage and support the use of organic farming methods in the county.
• Limit use of lawn pesticides (perhaps by limiting lawn size).

Implementation tools

Because of differences in pesticides, soils, and management practices, knowing which crops are grown in an area alone does not accurately indicate the risk to human health. However, knowing where pesticide use is likely to be heaviest may be useful in comprehensive planning if one of the goals is to minimize human exposure to potential contaminants in the environment.

Implementation tools that can be used to address groundwater issues in the planning process may include:

1. Education Tool: Education and citizen participation in making land use decisions, implementing land use goals, and taking private actions aimed at limiting pesticide contamination of groundwater.
1. Private well water testing and education programs offered by the University of Wisconsin – Extension can increase public awareness of pesticide contamination in groundwater and local government officials’ interest in taking proactive planning steps to protect groundwater. In Iowa County, for example, town officials began using groundwater information collected through such programs as criteria for siting new facilities and developments.^F15
2. The University of Wisconsin – Madison and UW - Extension have many educational programs in place to help farmers limit the use of pesticides and pesticide losses to the environment,^F33 such as the Integrated Crop and Pest Management (ICPM) program, which can be accessed and implemented locally through the county Extension office.
2. Environmental Assessment Tool: Environmental assessment requirements within zoning or subdivision ordinances to ensure that suitable sources of water for private wells are available on a proposed development site.
3. Facility Planning Tool: More detailed facility plans for potential contamination sources, such as spill containment plans for potential pesticide sources.
4. Regulatory Tools: including
1. Zoning
1. Performance zoning, which outlines general water quality goals that developers or other landowners can meet by a variety of methods.
2. Overlay zoning, which allows special regulations of sensitive environmental areas such as wellhead protection districts or groundwater recharge areas.
2. Density transfers can allow the transfer of development rights from one parcel that a community wants to protect to another parcel where the community wants development to occur.
5. Acquisition Tools, including:
1. Outright purchase of land needed for groundwater protection by communities or non-profit conservation organizations.
2. Conservation easements could limit land uses to those not likely to contaminate groundwater with pesticides.
3. Purchase of development rights can protect land from development with certain types of groundwater-contaminating activities while allowing the landowner to retain ownership of the land and the ability to sell or transfer it at any time.
4. Eminent domain allows government to take private property for public purposes with compensation to the owner, even without the owner’s consent. This tool could be used to acquire critical groundwater protection areas.
6. Fiscal Tools: including WDNR grant or loan programs to help communities assess and meet their needs in areas involving sensitive natural resources such as groundwater.^F34
7. Incentive Tools: Incentives from local governments to grow groundwater-friendly crops including
1. A community could identify agricultural lands in the recharge area for its wells and provide various incentives for farmers to enter into cropping agreements to limit pesticide inputs.
2. Woodbury County, Iowa offers property tax rebates to farmers who switch to organic methods.^F35
3. A community may hire a specialist to evaluate areas of high pesticide use and develop possible pesticide management strategies or promote low-pesticide agricultural systems or organic farming systems which forbid the use of synthetic pesticides.
4. A community may encourage food processors that purchase organic or groundwater friendly foods to locate or form in the area.

Drinking water with elevated levels of arsenic may lead to a variety of health effects, including:^F36 skin cancer, internal cancers (bladder, prostate, lung, and other sites), thick, rough skin on hands and feet, unusual skin pigmentation (dappling of dark brown or white splotches), numbness in the hands and feet, circulatory disorders, tremors, stomach pain, nausea, diarrhea, diabetes, depression.

In northeastern Wisconsin, most of the arsenic is found in a highly mineralized zone at the top of the St. Peter Sandstone aquifer. The oxidation mechanism that releases arsenic occurs naturally in some cases, but can also be triggered by either:^F3

• Local and regional drawdown (drop in water level) caused by increasing water use, which exposes the arsenic-bearing zone to the atmosphere or
• Well construction techniques that introduce oxygen into the aquifer.

However, revised WDNR drilling rules and special well casing requirements have greatly reduced well construction problems.^F44 Maps are available from the WDNR that show special well construction and well casing requirements by section for towns in Winnebago and Outagamie Counties.

In southeastern Wisconsin and the glacial moraines of northern Wisconsin, the mechanism by which arsenic is released from geologic materials is different. The arsenic is associated with iron oxides and is released by natural reduction reactions that cannot readily be prevented or controlled.^{F3, E38, E39} In such areas, alternatives are limited to treating water or using another (often shallower) aquifer, if one is present and not contaminated with nitrate or other human-induced contaminants.

Arsenic contamination could be addressed in comprehensive planning in the following ways:

• Maps and other resources can be consulted to determine the likelihood of arsenic contamination of drinking water supplies in areas designated for residential development, and possible need for alternate water supplies in those areas.
• Generalized maps can be found on the WDNR web site for both public and private water supplies sampled until 2000.
• Madeline Gotkowitz (mbgotkow@wisc.edu, 608/262-1580) at the Wisconsin Geological and Natural History Survey has done extensive research and public outreach on arsenic problems in Wisconsin’s groundwater.
• Testing and education programs can be conducted for owners of existing private wells in arsenic-prone areas to check current arsenic levels in private wells, to advise about treatment options, and to inform about ways to limit further arsenic release in the aquifer, where applicable.
• Restricting residential growth, encouraging or mandating water conservation, or finding alternate water sources may be beneficial in areas where oxidation is the primary method of arsenic release.

Volatile Organic Compounds
Volatile organic compounds (VOCs) are a group of common industrial and household chemicals that evaporate, or volatilize, when exposed to the air. Sources of VOCs include a variety of everyday products such as gasoline, fuel oil, solvents, degreasers, and dry cleaning solutions. When chemicals containing VOCs are spilled or disposed of on or below the land surface some of the chemicals can be carried down into the groundwater where they may pose a threat to nearby wells. Some VOCs are quite toxic while others pose little risk. Health risks vary depending on the type of VOC, but effects of long-term exposure can include cancer, liver damage, spasms, and impaired speech, hearing, and vision.^F40

Pharmaceuticals and Personal Care Products
The list of pharmaceuticals is long and includes such medications as tranquilizers, pain killers, antibiotics, birth control, hormone replacement, lipid regulators, beta blockers, anti-inflammatories, chemotherapy, antidiabetics, seizure control, veterinary drugs, antidepressants, and other psychiatric drugs. There is a related category of chemicals referred to as "personal care products" that includes cosmetics, perfumes, soaps, sunscreens, insect repellants, and so forth. The volume of pharmaceuticals and personal care products entering the environment each year is about equal to the amount of pesticides used.

In 2000 the U.S Geological Survey conducted a nationwide assessment of drugs in streams and groundwater. They picked locations likely to be contaminated, but found pharmaceuticals in about 60% of groundwater samples. Sources of discharge of pharmaceuticals to the environment include wastewater treatment plants, onsite wastewater treatment systems, landfills, sludge and manure spreading, and livestock feedlots. Why be concerned about traces of chemicals that were designed to be consumed? We're only beginning to understand the health effects. Because of the low concentrations, any effects are likely to appear only after years of exposure. A real concern is that some of the drugs are endocrine disruptors. Endocrine glands, such as the thyroid, pituitary or thymus send hormones, such as adrenaline, estrogen or testosterone to specific cells stimulating certain responses. There are hundreds of different hormones, and they are messengers that regulate a multitude of normal biological functions, such as growth, reproduction, brain development, and behavior. The delivery of hormones to various organs is vital, and when the delivery, timing, or amount of hormone is upset, the results can be devastating and permanent. Chemicals that are similar to hormones ("hormone mimics") can fit onto the receptor sites on the target cells and either block the real hormones or trigger abnormal responses in the cells. Scientific studies have indicated links between endocrine disruptors and reproductive disorders, immune system dysfunction, certain types of cancer, congenital birth defects, neurological effects, attention deficit, low IQ, low sperm counts, and early onset of puberty in girls.^F41

Chloride
Chloride at levels greater than 10 mg/L usually indicate contamination by onsite wastewater treatment systems (including water softener regeneration), road salt, fertilizer, animal waste, or other wastes. Chloride is not toxic in concentrations typically found in groundwater, but some people can detect a salty taste at 250 mg/L. Levels of chloride that are above what is typical under natural conditions indicate that groundwater is being affected by human activities, and extra care should be taken to ensure that land use activities do not further degrade water quality.^F42

The WDNR Bureau of Remediation and Redevelopment Tracking System (BRRTS) contains information about locations at which there have been releases of hazardous or potentially hazardous substances to the lands, waters, or air of the State of Wisconsin. Degradation of groundwater quality is one of the primary concerns at BRRTS sites, but soil, vapor, air, and surface water contamination are also areas of concern.

A Hazardous Substance is defined in s. 292.01, Wis. Stats., as “any substance or combination of substances, including any waste of a solid, semisolid, liquid or gaseous form which may cause or significantly contribute to an increase in the mortality or an increase in serious irreversible or incapacitating reversible illness, or which may pose a substantial present or potential hazard to human health or the environment because of its quality, concentration or physical, chemical or infectious characteristics. This term includes, but is not limited to, substances that are toxic, corrosive, flammable, irritants, strong sensitizers or explosives as determined by the WDNR.”

Types of hazardous substance occurrences or discharges that are documented in the BRRTS database include:

• Abandoned Container (AC) – an abandoned container with potentially hazardous contents has been inspected and recovered, but discharge to the environment has not occurred.
• Leaking Underground Storage Tank (LUST) – a leaking underground storage tank has contaminated soil and/or groundwater with petroleum. Petroleum products contain cancer-causing and toxic substances, but may biodegrade, or break down naturally in the environment, over time.
• Environmental Repair (ERP) – sites other than LUSTs that have contaminated soil and/or groundwater. Industrial spills or dumping, buried containers of hazardous substances, closed landfills, and leaking above-ground petroleum storage tanks are potential ERPs.
• Voluntary Party Liability Exemption - an elective process in which a property owner conducts an environmental investigation and cleanup of an entire property and then receives limits on future liability for that contamination.
• Spills – discharges of hazardous substances, usually cleaned up quickly.

For further information, see the BRRTS web site glossary.

BRRTS information provides a snapshot of contaminated sites that need to be considered when developing land use plans. Steps toward incorporating BRRTS information into a comprehensive plan include

1. Inventory contaminated sites and identify their status. The summary document prepared for each county on this web site lists BRRTS sites that are still open. Other sites of interest may include closed sites and conditionally closed sites on the BRRTS list, or sites in the community that have not yet been investigated by WDNR but are suspected to have had hazardous releases in the past.
2. Identify land use restrictions and deed restrictions assigned to contaminated properties. Land use restrictions are placed on BRRTS sites to protect public health and the environment. A BRRTS site that is “closed” and requires no further cleanup action may still have residual soil or groundwater contamination. If it does, it is moved to the GIS Registry of Closed Remediation Sites. Sites on the Registry have restrictions that may include
   • site maintenance plans
   • requirement for WDNR approval before new well construction
   • special required well construction features
   • special precautions when excavating soils
   Details about such restrictions are available in the GIS Registry of Closed Remediation Sites fact sheet.
3. Identify properties on which redevelopment would be desirable for the community. Communities may be eligible for assistance in redeveloping contaminated or formerly contaminated industrial or commercial sites that are abandoned, idle or underused through WDNR initiatives aimed at brownfield redevelopment. Helpful tools for redevelopment include
   • environmental liability exemptions
   • financial incentives
   • WDNR assurance letters

Details on programs to help with brownfield redevelopment are found in the WDNR publication Brownfields and Comprehensive Planning

A list of WDNR staff contacts to assist with various aspects of remediation and redevelopment of contaminated sites, including assistance grants for local governments, is available online.

Wisconsin's solid waste management program has been in place for over 30 years. In the first two decades of the program, efforts were primarily directed toward: licensing existing solid waste facilities; closing poorly located or operated facilities; and ensuring that new solid waste facilities were properly located, designed, constructed, operated, closed, and maintained. During this period, the vast majority of municipal and industrial solid waste generated was landfilled.

In the 1990s, things began to change. Wisconsin's Recycling Law was passed in 1990, with most of the requirements taking effect in 1995. In 1997, ch. NR 538, Wis. Adm. Code was promulgated, facilitating the beneficial use of industrial byproducts. These two milestones resulted in significant and still-increasing quantities of waste being diverted from landfills.

As of the summer of 2001, Wisconsin has the following numbers of licensed/regulated facilities in operation: 44 municipal solid waste landfills; 41 industrial waste landfills; 36 construction and demolition waste landfills; 1,446 solid waste transporters; 78 transfer stations; 64 processing facilities; 6 municipal waste combustors; 148 composting facilities (mostly yard waste); and 125 woodburning sites.^G5

The solid waste program strives to ensure proper management of solid waste and works with its customers to increase waste reduction, reuse, and recycling. For more information on solid waste management in Wisconsin, see the Future of Waste Management Study completed in 2001.

A complete list of licensed landfills in Wisconsin for 2007 can be found online.

More information on solid waste is available from the WDNR.

In 1980, Congress passed the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA), commonly known as the Superfund law. The Superfund law created a tax on the chemical and petroleum industries. The tax went into a trust fund to help pay for cleaning up abandoned or uncontrolled waste sites.

The U.S. Environmental Protection Agency (EPA) administers the Superfund trust fund and works closely with state and local governments and tribal groups to remediate sites that may endanger public health or the environment. The contamination at many of these sites was created years ago when environmental regulations were virtually nonexistent and companies dumped or emitted hazardous materials freely into the environment. Years later the threat to humans and the ecosystems remains so great that the sites need to be cleaned up.

Unfortunately, since much of this contamination was caused so many years ago, it can be hard to find the parties responsible, or the parties responsible may be unwilling or unable to pay for the cleanup. In these cases, the Superfund trust fund can be used to pay for most of the cleanup process. States must pay for a portion of such cleanups.

CERCLA also provides EPA with enforcement tools to compel those responsible for causing the contamination to pay for the cleanup, including the issuance of administrative orders. If the trust fund is used, then EPA and the state may go to court to recover their expenditures from those who are responsible.^G7