2021 Water-Quality Survey

Researchers seek more volunteers to test wells, expand database

Researchers want to collect more data, more frequently, from more wells as a service to area residents and for their ongoing studies of the quality of Door County’s drinking water.

For the past three years, researchers at the Environmental Research and Innovation Center (ERIC) at the University of Wisconsin-Oshkosh have encouraged well owners countywide to take samples during one 30-hour period during the fall. To improve their database, they’re working to add spring testing when rains are most likely and groundwater recharge occurs, said Carmen Thiel, ERIC lab manager.

In particular, the researchers need more participation from parts of the county where there has been none, although the researchers also welcome the same well owners to participate every year – and advise everyone to test their well water twice a year.

“We also want to recruit other wells in other areas of the county so we can get spatial distribution,” Thiel said.

In 2020 and 2021, Washington Island well owners began participating in the survey, thanks in part to test kits becoming available by mail – with postage paid through a donation from Door County Medical Center. Thiel was glad to see participation from Washington Island because the researchers have a goal of collecting test data year after year from at least one well in each square-mile section of the county.

Throughout the three years of testing, the lab has not seen any participation from a roughly seven-mile-by-five-mile area in the center of the peninsula north of Sturgeon Bay toward Egg Harbor.

“Participation was good, slightly down from last year, but we had better coverage of the county,” Thiel said. 

The researchers maintain great interest in Door County’s crack-filled karst geology and its groundwater. Water runoff and pollutants can travel rapidly downward or in a stair-step fashion to the water table through fissures in the county’s bedrock.

“Things can go from the surface to hundreds and hundreds of feet below the surface in your groundwater in a matter of hours or days,” said Greg Kleinheinz, a Baileys Harbor property owner who’s also the chair of the Department of Engineering and the engineering technology director for the ERIC lab.

The lab received 148 samples in 2019, 295 in 2020 and 217 in 2021 containing coliform bacteria. These bacteria can come from agricultural practices or animal, bird or human waste; or they can develop in well water through various means, ranging from runoff, to damaged or deteriorated well casings, to well caps or distribution-pipe issues.  

This year, 166 of 217 samples had no coliform present, and 30 of those had between 1 and 9.9 parts per million (ppm) of coliform. A part per million is equal to about three droplets in a 40-gallon barrel. State standards consider anything above zero “unsafe” for public water systems, but coliform can show up if a faucet wasn’t disinfected properly prior to testing or if a property owner handled a test bottle incorrectly. Bacteria are present on human hands, in soil and almost everywhere, Kleinheinz said.

Any coliform might prompt additional voluntary testing, follow-up monitoring or possible action by a homeowner, but levels above 10 ppm should sound more of an alarm for property owners, the researchers said. Fourteen tests showed more than 10 ppm, and seven showed more than 100 ppm.

The pathogen E. coli was detected in four tests, though only one had a level greater than 10 ppm, Thiel said. Kleinheinz said E. coli presence indicates that the contamination was recent because E. coli cannot survive for long in a well.

Nitrates – present in everything from field runoff to grass and golf-course fertilizers – were detected in 25% of 215 samples. Most of those were trace amounts, but five came back at the unsafe level of greater than 10 ppm, and 25 others were in the 5- to 10-ppm range.

Kleinheinz said that if people see the nitrate level steadily increasing in that 5-ppm range and higher, they should start to look into the problem.

Testing and actions for private wells are voluntary, and Kleinheinz said people display different tolerances for risk. One property owner with tests rising from 5 to 6 to 7 ppm, for instance, responded by installing a new well and a treatment system, and another with similar results said he figured he had a few years before he should take action. Kleinheinz said nitrates have been linked to blue baby syndrome, so it’s a particular concern for infants and pregnant women.

For the second year, nitrate was found in several wells north and northwest of Sturgeon Bay near the Green Bay shoreline. Kleinheinz said he doesn’t know the precise reason – such as whether its presence stems from geological features in that area – but in many cases, those are likely older properties with shallow (50 feet or shorter) wells.

Need a Well Test or Want More Information?

• UW-Oshkosh ERIC lab: [email protected] or 920.424.3148

• Wisconsin Department of Natural Resources’ Green Bay service center: 920.662.5147, 920.360.2688 or

• Door County Public Health, Door County Soil and Water Conservation Department and Door County Land Use Services Department:

• Interns also work at the Crossroads at Big Creek laboratory, 2041 Michigan St. in Sturgeon Bay, from Memorial Day through Labor Day each year.