Rock County’s interactive online Nitrate Risk Mapping Tool allows residents to input their addresses and identify an estimated risk of nitrates reaching the groundwater in their area.


Nitrate contamination of groundwater should be the focus of a state task force examining Wisconsin’s water issues, Rock County Board Supervisor Wes Davis said.

“It’s terribly important that we began a conversation about nitrates,” Davis said.

He was among those attending a Wednesday hearing of the the state Water Quality Task Force at Blackhawk Technical College.

“There are other issues we are worried about, too, such as lead and a host of other things that are problems, but nitrates have risen to the surface, and that’s what we need to deal with at this time,” Davis said.

The task force, a bipartisan group of legislators from across the state formed by Assembly Speaker Robin Vos, made a stop in Janesville to hear from organizations and residents about issues with water contamination, runoff and other topics related to the quality of water in Wisconsin.


Presentations were given by several local officials including Rock County Conservationist Thomas Sweeney and county Environmental Health Director Rick Wietersen.

Nitrate contamination can cause birth defects and illnesses if not treated. Contamination can be caused by fertilizers and manure.

According to the presentation, agricultural areas and areas with porous bedrock or sandy soil are more susceptible to nitrate contamination.

State health standards say the maximum amount of nitrate allowed in water is 10 milligrams per liter, but more than 94,000 houses with private wells across Wisconsin are above this threshold, according to the presentation given by Sweeney and Wietersen.

In Rock County, it’s estimated 4,000 of the 15,000 wells may exceed the recommended nitrate limits. The Rock County Public Health Lab tests about 800 wells annually.

“The nitrate issue in groundwater is not a new one, but this effort that the task force, as well as other efforts organized in recent months, have been prompted through more local studies being done on groundwater contamination,” said Matt Kruger, executive director of the non-profit Wisconsin Land & Water Conservation Association.

Though the long-term fix of replacing a well can be costly, Sweeney said there are other options.

“Short-term answers are a deeper well, treatment or using alternate water supplies. A lot of people just choose to go to the grocery store and get the gallons of water and use that for their drinking purposes,” Sweeney said.

The hazards of high nitrates are associated with consumption more than bathing, he said.

Pat Mullooly is a local corn and soybean farmer who works with the Wisconsin Soybean Association and the Rock County Nitrate Working Group.

He said locals and farmers are willing to help fight water contamination, citing management techniques that change how farmers till the land and plan nutrient management.

“The agribusiness in the area is very committed to the environment and sustainability,” Mullooly said.

And while the state Water Quality Task Force will move on to the next city after Wednesday’s session, Davis said the conversation it helped start is important.

“In parts of our county, the nitrate problem is worse than it is in Flint, Michigan,” Davis said. “But we don’t want to be alarmists. We want to approach this in an organized fashion and try to build communities of support. Working together is the key.”

Krueger said people need to be informed and speak up.

“There is a water quality crisis that we are responding to right now, but there is also a crisis in the agricultural community,” Krueger said, “and that should prompt a rethink of how we’re doing things.”