A well in Johnson County will help scientists monitor groundwater levels. Here’s why that’s important

A groundwater well will be drilled in Johnson County’s Kent Park this summer in a yearslong effort to monitor the amount of water available in an underground aquifer.

Rick Langel, a geologist with the Iowa Geological Survey, said the well will be part of a proactive project that will help fill in data gaps in the decades going forward.

The goal of the project is to create a long-term record of the well to monitor groundwater levels over time.

An added bonus, Langel said, will be if the well helps scientists collect water chemistry data, like traces of “forever chemicals.” The industrial chemicals — perfluoroalkyl and polyfluoroalkyl substances, or PFAS — are called “forever chemicals” because of how long they can last in human bodies and the environment.

Langel said Johnson County has gaps in its data about groundwater in part because it has fewer groundwater wells than other counties, such as Linn County.

He said the groundwater wells in Linn County have been in place since the early 1970s, collecting data about the aquifers for 50 years.

“It's great to be able to go back and see if it has changed. What's different? Is it the same or has it changed?” Langel said. “It's really nice having that long-term record.”

Langel said it will be 10 to 15 years before Johnson County, IGS and the U.S. Geological Survey have enough “meaningful” data from the new well that can be used in future models and analysis work.

The new well will tap into the Silurian Aquifer, which serves as a major groundwater source for the Midwest and Iowa in particular.

An aquifer is an underground layer of rock that holds water and allows water to flow through it.

The Silurian Aquifer is able to replenish itself but since the aquifer is hundreds of feet under the surface of the Earth, it can take years — even centuries — for it to replenish.

The aquifer’s recharging time also can be affected by water pumping — by cities, homes and other entities — and can lead to a decline in water levels.

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Langel said drilling of the well could begin any day. The agreement with the county states that the well can remain operational at the park for a minimum of 10 years.

But “honestly, I'm hoping that the people at Kent Park will let us keep that well there forever as part of the process,” Langel said. “We'll keep monitoring it as long as it's there and as long as it's still functional.”

USGS research into Johnson County’s aquifers

Johnson County’s effort to install a groundwater well in Kent Park comes after the U.S. Geological Survey found that the Silurian Aquifer in the area will see a “drawdown” of as much as 13 meters of water in the next two decades, indicating that the aquifer’s storage will decrease in the coming years.

Water “drawdowns” refer to the lowering of the water table underground due to pumping. So when a well is pumped to extract groundwater, the water level in the aquifer decreases.

Data from a different well that’s tapped into the Silurian Aquifer in Johnson County, near the University of Iowa campus, shows the drawdown level in the well in March 1995 was 221.1 feet deep.

Thirty years later, in June 2025, the drawdown level in the same well grew to 271.7 feet deep, marking a 50.6-foot drawdown increase.

Langel said the drawdown increase is due to pumping, as well as drought conditions in Iowa.

If the 13-meter prediction from the USGS holds true, that would be an additional 42.6 feet of drawdown in the well.

The increasingly deep drawdown level is partly due to population increases in the Iowa City area and a higher demand for water.

According to a USGS study of groundwater abundance that was conducted in 2005 and again this year, Johnson County and Iowa City have increased their water use from the Silurian Aquifer by 25 percent in those 20 years.

Langel said the aquifer has to be replenished naturally, meaning that geologists wouldn’t pump water back into the Silurian because it would essentially be taking water “from one aquifer to put it into a different aquifer.”

The USGS presented its 2025 study — which Langel said the Iowa Geological Survey was an “unofficial partners” on — at a Johnson County Board of Supervisors meeting May 14.

Judith Thomas, supervisory hydrologist with the USGS’ Central Midwest Water Science Center, said officials from Johnson County reached out to her team in 2023 regarding the groundwater model USGS completed for the county in 2005, in hopes of updating that model.

Download: Overview of USGS report.pdf

Thomas said as 2025 was nearing, marking 20 years since the last aquifer study in Johnson County, officials from the county asked USGS to run a new model with new data to determine the current water levels in the Silurian Aquifer.

“We took that project and looked at what the findings were from the 2005 model and found some of what could be improved in the future,” Thomas said.

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After looking at past and current Johnson County groundwater levels in the Silurian Aquifer, USGS ran several scenarios out to 2045 to predict how the groundwater could be used.

Thomas said that one of their scenarios showed a water drawdown in pumping centers in the coming decades.

“We predicted that we would see drawdowns of four to 13 meters in these pumping centers for each of these communities that's using the Silurian as their water source,” Thomas said.

Langel said the other communities include an area east of Solon, one in Shueyville, another west of Swisher and a bit west of Tiffin. He said these locations were considered for a groundwater well to study water levels.

Thomas said it isn’t that the aquifer in the Johnson County area is unhealthy, but that since the water being consumed by Iowans is hundreds of years old, the “finite resource” must be closely monitored.

For a “municipality, there's nothing you're going to do in the next five years that's going to fix something that is affecting 100-year-old water,” she said.

Langel said that a few other wells are having a similar drawdown issue in Iowa — particularly a well in Sioux County — but there aren’t wells in Eastern Iowa specifically that are facing the same challenges that the Silurian is seeing in Johnson County.

He said that there is some concern about the Jordan Aquifer that spans through Iowa and the Midwest, but the circumstances are different because that aquifer is primarily used for industrial, rather than residential use.

In her presentation to the Board of Supervisors, Thomas said the limited availability of long-term groundwater data in the Silurian Aquifer will continue to be a challenge in understanding the aquifer’s conditions.

But Langel hopes the new well will provide that long-term data.

Details of the well

Langel said the USGS identified several areas in Johnson County where there were data gaps or where more data would be helpful.

Kent Park was chosen for the well because the park is owned by Johnson County Conservation.

Brad Freidhof, Johnson County Conservation director, said the project is important because water is a vital resource that is overlooked and that some people take for granted.

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“Both water quantity and quality impact our availability of water as Iowans. We've always had a strong interest in water quality in Iowa,” Freidhof said. “A lot of us like to recreate out in the water, the streams, lakes, rivers that crisscross our state, so it's important to make sure that we're recharging aquifers underneath us that provide for our drinking water and all the activities we do here in the state of Iowa.”

Generally, a well can cost anywhere between $25,000 to $50,000, Langel said. The exact price of the new Kent Park well is not yet known because it’s unclear how deep it will need to be drilled. The well is being funded by USGS.

Langel said the well will likely be about 575 feet deep. The Iowa Geological Survey said it estimates having to drill about 380 feet deep just to reach the aquifer.

Langel said the project is trying to get “data to answer questions” they don’t know yet.

“Ultimately, the big, long-term goal is just to document long-term changes in the aquifer and to do that you need a long period of record,” Langel said.

Olivia Cohen covers energy and environment for The Gazette and is a corps member with Report for America, a national service program that places journalists in local newsrooms to report on under-covered issues.

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Comments: olivia.cohen@thegazette.com