Protecting drinking water from nitrate pollution
Wisconsin has a vast source of water underground, and many people, communities, and industries rely on groundwater for their needs.
While for many people, private wells that draw groundwater are a reliable and safe source of water, for many others, groundwater pollution poses a major challenge.
There are many contaminants from many sources that pollute groundwater in Wisconsin.
However, nitrate plays an outsized role in groundwater pollution problems around the state.
What is nitrate?
Nitrate is one chemical form of the element nitrogen and is a critical component of life. Nitrogen is found in everything from humans to plants, and follows a natural cycle of moving from the atmosphere to the ground, similar to the water cycle.
Nitrate is the most widespread groundwater pollutant in Wisconsin.
How does nitrate get into groundwater?
In an agricultural state like Wisconsin, nitrogen in the form of fertilizer and manure is spread on farm fields to help promote and accelerate the growth of crops.
An overabundance of nitrogen use in agriculture has led to nitrate leaching into groundwater. While other sources, like septic systems, also contribute to nitrate pollution in drinking water, estimates suggest that 90% of the nitrate contaminating groundwater come from agricultural sources.
Local geology and the type of soil present both influence how susceptible an area is to groundwater pollution.
In areas with cracked bedrock or sandy soils, contaminated water on the earth’s surface can easily and quickly make its way into the groundwater. Aquifers, the rock layers containing groundwater, made up of sandstone or dolomite contain many fissures or cracks, making it easy for water to travel through without removing contaminants.
Areas with sandy soils are particularly vulnerable to nitrate pollution. The sand might filter out bacteria, but nitrates move quickly with the water through the sand and down into the aquifer.
Percentage of people in WI who get their drinking water from a private well
Upper estimate of private wells in WI contaminated with unsafe levels of nitrate
Estimated amount of nitrate pollution in groundwater from agriculture sources
What’s at risk?
Our health. Nitrogen is a critical elemental building block of life, but too much of it in certain forms, like nitrate, can pose significant health risks to everyone, not just pregnant women or small children.
Nitrate is linked to Blue Baby Syndrome, a condition that reduces oxygen in the bloodstream in young babies, causing them to turn a blue-gray color. It can also cause neural birth defects in fetuses, which can be life threatening.
In adults, excessive nitrate exposure is linked to increased risk ofa thyroid disease, colon cancer and non-Hodgkin’s lymphoma.
But there are also risks to our economy. A study conducted by Clean Wisconsin and Environmental Working Group estimates that the health consequences of nitrate pollution in drinking water costs Wisconsin residents up to $80 million in annual medical expenses.
Nitrate pollution in drinking water is linked to:
Blue Baby Syndrome
Neural birth defects
“Vicious Cycle: The story of Wisconsin’s most common contaminant”
Case study: Southwest Wisconsin
Southwest Wisconsin is a part of the state with extensive fractured and porous bedrock and shallow soils, making the groundwater susceptible to contamination. While it was widely assumed that this area had groundwater contamination from nitrates and bacteria, no conclusive study had been conducted.
Clean Wisconsin had encouraged state and local leaders for over two years to fund a study of the three-county region in the southwest corner of the state to determine the extent and sources of contamination to private wells.
In the first round of testing in late 2018, the study found that the percentage of wells in Grant, Iowa, and Lafayette Counties that tested positive for coliform bacteria or above the safe level for nitrate was higher than the state average, with 42 percent of wells tested contaminated with one or both pollutants.
These results prompted Assembly Speaker Robin Vos to form the Speaker’s Task Force on Water Quality.
This study is ongoing, but it has already made clear that groundwater pollution is a serious challenge in Southwest Wisconsin that must be addressed through robust policy and increased funding.
What’s being done about it?
Clean Wisconsin has been a leading voice in calling for state efforts to reduce nitrate pollution in groundwater.
After years of work to encourage state officials to tackle the nitrate pollution issue, Gov. Evers announced in 2019 the start of work to develop new rules for how nitrogen is applied to farm fields. These new administrative rules will stipulate how nitrates from commercial fertilizer and manure are applied to farm fields.
This rulemaking process is an important step for protecting rural drinking water across the state, but much more needs to be done. Increased funding for programs to address water pollution, more support for people with contaminated wells, and investment in county conservation staff is needed to make significant strides to tackle and start solving this public health crisis.
Even though wetlands cover more than five-million acres of our state, they don’t always top the list of Wisconsin’s most beloved outdoor spaces. But maybe they should, especially considering we’ve lost more than half of our wetlands in just the last century or so.
Climate change is making summers hotter, leaving people without air conditioning in Milwaukee and other cities vulnerable to its dangerous health impacts. Low-income communities and communities of color are often more likely to experience the harsh impacts of severe heat brought by climate change.
Recently, La Crosse area residents are discovering PFAS in their drinking water, many over the state’s recommended limit of 20 parts per trillion, from firefighting foam used by the city’s fire department.
Wisconsin State Supreme Court sides with Clean Wisconsin in two critical environmental casesAfter years of court battles, the Wisconsin Supreme Court handed environmental advocates in the state a pair of victories today. The Court ruled in two separate cases, each...
Four environmental and agricultural groups, working as partners to bring about long-term solutions to Wisconsin’s water quality issues, detailed significant investments today that they urge the state to make when shaping the next budget and beyond.
Clean Wisconsin praised the draft rules to reduce nitrate pollution in drinking water and the accompanying economic analysis released by the Department of Natural Resources (DNR) on Friday.
Four environmental and agricultural groups are coming together to advocate for meaningful state-level policy changes that support clean water and resilient farms.
Early last year, in his State of the State Address, Gov. Evers declared 2019 the Year of Clean Drinking Water. While 2019 is behind us, the governor has continually reiterated—through his words and actions—his support for efforts to address polluted drinking water that plagues too many Wisconsin residents.
MADISON, WI — Clean Wisconsin applauds Gov. Tony Evers for signing a bill into law on Tuesday that sets up a nutrient pollution trading clearinghouse. Amber Meyer Smith, Vice President of Programs and Government Relations for Clean Wisconsin, made the following...
Our research puts a number on the nitrate pollution crisis being felt around the state. Not only is this a serious threat to human health, but it has a major impact on our state’s economy.