With many Iowans concerned about the quality of their drinking water, Linn County experts are mapping water contamination sources to try to understand where its groundwater is most vulnerable.

Stephanie Tassier-Surine, a geologist at the Iowa Geological Survey, says they’re looking at the concentration of several potential problem areas, including CAFOs, or concentrated animal feeding operations.

“There are 334 LUST sites, that’s leaking underground storage tank sites, 207 contaminated sites, nine landfills either existing or past, 37 CAFOs with 263 potentially manured fields,” she says.

The geological study will overlay pollution sites with soil and bedrock data. The county will then be able to better understand which areas of its aquifer are more at risk of contamination — then, site industry or draw drinking water in safer areas.

Tassier-Surine says a preliminary map layers the county’s known pollution sites with geological studies and hydrological calculations.

“So you can see there are certain areas there that are higher risk either because of the geology,” she says, “because there’s a contamination site nearby, or because its an aquifer that you’re pumping a lot of water from.”

Researchers are scheduled to finalize the map by the end of the year.

How vulnerable your groundwater is depends on where pollution is coming from and how it’s moving through the soil. If the earth below a pollution site is porous, she says an aquifer is more at risk. If it’s more dense, the more likely more contaminants will get filtered out.

(By Eliza Billingham, Iowa Public Radio)