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Look up
data about the quality of groundwater near homes or businesses or get an estimate of groundwater availability.
the quality and quantity of groundwater for your family, business customers and community.
where your groundwater comes from and how it moves underground to reach your drinking water well and the lakes and streams you enjoy.

GCC Report to the Legislature Groundwater quality

Groundwater contamination from human and natural causes occurs across Wisconsin. This is of particular concern for the 70% of Wisconsin residents who obtain their drinking water from groundwater. Other groups that are affected by groundwater quality include farmers who rely on groundwater for irrigation, industrial and commercial users and the environment.

Trends in groundwater quality in Wisconsin are mixed — both increases and decreases in groundwater quality are observed. Information about the distribution of naturally–occurring metals is improving. Continued attention is needed to the occurrence of increasing and emerging contaminants, including nitrates, bacteria and viruses.

Common contaminants — usually acute health effects


photo of pathogens

Escherichia coli. Photo credit: National Institute of Allergy
and Infectious Disease.

Pathogens are organisms or other agents that can cause disease, including microorganisms such as bacteria, viruses and protozoa that can cause waterborne disease. Pathogens in groundwater can often be traced to human or animal fecal wastes.

» Read more.


Photo of a tractor in field

Photo credit: DNR.

Nitrate is Wisconsin's most widespread groundwater contaminant. Most nitrate in groundwater (90%) is due to agricultural inputs.

» Read more.

Common contaminants — usually chronic health effects


Photo of pyrite

Pyrite. Photo credit: JJ Harrison.

Arsenic occurs naturally in soil and rock, typically bound to other minerals such as pyrite (pictured). Under certain environmental conditions, arsenic can dissolve and be transported in groundwater.

» Read more.


Photo of a plane spreading pesticides

Photo credit: DATCP.

Pesticides are a broad class of substances designed to kill, repel or otherwise disrupt living things that are considered pests. Normal field applications, spills, misuse or improper storage and disposal can all lead to pesticide contamination in groundwater.

» Read more.


Photo of radioactive symbol

Photo credit: Pixabay.

Radionuclides are radioactive atoms. It is possible for radionuclides to be man–made but they also occur naturally in rock formations and are released to groundwater over millions of years by geochemical reactions.

» Read more.

Volatile Organic Compounds

Photo of chemical container

Photo credit: DNR.

Volatile Organic Compounds (VOCs) are a group of common industrial and household chemicals that evaporate or volatilize when exposed to air. Improper handling or disposal of VOCs is often the reason why they occur in groundwater.

» Read more.

Less common contaminants

Emerging contaminants

Photo of prescription pill bottle

Photo credit: US Department of Defense

Emerging contaminants are compounds that are increasingly being detected in groundwater and may have harmful human health or environmental impacts. Many, but not all, of these emerging contaminants enter the groundwater from wastewater or solid waste sources.

» Read more.

Additional Resources

Last revised: Tuesday August 30 2016