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Maureen Muldoon

Maureen Muldoon

A University of Wisconsin Oshkosh hydrogeologist brings 30 years of experience studying the dolomite aquifer to help sort out Kewaunee County’s well water contamination issues.

UWO’s Maureen Muldoon teamed up with scientists from the U.S. Department of Agriculture and the U.S. Geological Survey in a two-year water quality assessment of the county.

Muldoon, who has previous experience as a hydrogeologist with the Wisconsin Geological and Natural History Survey, joined UWO’s Department of Geology faculty in 1998. Her research focuses on applied groundwater questions throughout Wisconsin, including investigations of groundwater quality and flow in carbonate rocks, land-use impacts on groundwater quality and delineation of wellhead protection zones in fractured rock.

Muldoon and Mark Borchardt, of USDA’s Agricultural Research Service, recently shared data from their assessment with hundreds of residents at a public meeting at the Kewaunee County fairgrounds.

While the data showed that the the overall contamination rate of private wells in Kewaunee County by bacteria or elevated nitrate is 26 to 28 percent, the rate in certain vulnerable areas associated with fractured bedrock rises to 50 percent. At depths to bedrock of less than 20 feet, contamination rates generally exceeded statewide averages.

Muldoon explained that in areas with fractured bedrock like those in Kewaunee County water can flow very quickly during groundwater recharge, so contaminants don’t have time to dilute and break down before reaching the aquifer.

When farmers spread manure in the fall and spring, the contaminants can quickly reach the wells.


UWO students measure water levels and collect samples from a Kewaunee County well Muldoon installed for a previous study.

“A lot of people in the county are aware that there are just certain times of year that the wells are contaminated and they don’t drink the water,” she said. “Unfortunately, not everyone can afford bottled water or treatments.”

In many areas of the country, sampling well water once a year is enough to monitor contamination levels.

“But in areas with fractured bedrock like in Kewaunee County, your well can be fine one day and contaminated the next,” Muldoon explained.

Moving forward, Muldoon said the study results may have implications for groundwater regulations.

Future research efforts include developing a water table map and a computer model and determining best practices for agricultural management in the county, she added.

In addition to her research at UW Oshkosh, Muldoon teaches three hydrogeology courses and environmental geology as well as leads a geology field trip to the Colorado Plateau and a field course in Belize.

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