An ongoing water quality study has set off alarm bells throughout southwest Wisconsin after about 42 percent of private wells tested showed signs of contamination.

The Southwest Wisconsin Groundwater and Geology Study, which examined 301 wells in Grant, Iowa and Lafayette counties, also is raising questions about water quality testing elsewhere in the tri-state area.

Russell Tell, an environmental specialist for the Iowa Department of Natural Resources, manages private well-testing in the state. He said large-scale well-testing has not recently been performed in northeast Iowa.

He said county health departments can test private wells for total coliform bacteria, which does not itself cause illness, but suggests the presence of other contaminants. Results are tracked by the Iowa Department of Public Health.

Of three requested total coliform bacteria tests conducted on private wells in 2017 in Dubuque County, one came back positive.

In Delaware County, 389 tests were conducted, 108 of which — about 28 percent — tested positive for total coliform bacteria. In Jackson County, 40 of 179 wells — 22 percent — tested positive. And in Clayton County, 72 of 193 wells — 37 percent — tested positive for coliform bacteria.

In 2011, the University of Iowa Center for Health Effects of Environmental Contamination tested 473 private rural drinking water wells in 89 Iowa counties. Findings showed that 43 percent of tested wells had total coliform bacteria. About 49 percent tested positive for high levels of nitrates, and 48 percent tested positive for arsenic.

The center is conducting another study of private wells in northeast Iowa. Bill Field, a professor at the college of public health at the University of Iowa, said 50 private wells in northeast Iowa are being tested to check for possible contamination from insecticides.

Field said he thinks that well contamination in Iowa is not given adequate attention. He said wells are susceptible to contamination due to chemical runoff from farms.

“We’re seeing nitrogen in these wells, so we know that it is coming from runoff,” Field said. “Right now, we’re trying to see what exactly is getting into these wells.”

Some testing also has occurred in Jo Daviess County, Ill.

Walt Kelly, section head for the groundwater science division of the Illinois State Water Survey, said a series of water quality tests were conducted in 2015 and 2016 in Jo Daviess County. Twelve private wells and about 30 natural springs were tested for water quality.

“The well (water) quality was pretty good,” Kelly said. “It was really in the springs that were more areas of concern.”

Kelly attributed the condition of the springs to water runoff from roads and farms.

Sandra Schleicher, interim public health administrator for the Jo Daviess County Health Department, said the county tests new wells and performs tests under special circumstances. For example, wells can be tested to ensure a newborn baby has access to clean water.