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Studying Arsenic in Iowa’s Groundwater

Posted on August 2nd, 2011
The Des Moines Lobe was created more than 12,000 years ago by the last glacier to enter Iowa. It is known to have left deposits of arsenic. A new study will measure the presence of arsenic in private wells in Cerro Gordo County.

The Des Moines Lobe was created more than 12,000 years ago by the last glacier to enter Iowa. It is known to have left deposits of arsenic. A new study will measure the presence of arsenic in private wells in Cerro Gordo County.

Many Iowans who use private well water may be unknowingly consuming arsenic in their drinking water.

Arsenic is considered one of the most carcinogenic substances in the world. Long-term exposure can lead to changes in the skin, including cancer; cancer of the bladder, kidney, and lung; and possibly diabetes, high blood pressure, and reproductive disorders.

Arsenic occurs naturally in every Iowa aquifer. In some areas, concentrations in private wells are higher than the EPA’s maximum contaminate level (MCL) of 10 parts per billion, putting Iowans at risk for potential illness. Research Scientist Doug Schnoebelen of IIHR—Hydroscience & Engineering is working with Brian Hanft, deputy director of the Cerro Gordo County Public Health Department, as co-principal investigators for a new five-year grant funding a study of arsenic in private wells in Cerro Gordo County, where the levels are particularly high.

Schnoebelen says the high arsenic concentrations could be the result of a combination of naturally occurring arsenic and geochemical conditions that mobilize the arsenic from rock to water. A recent study of private wells in north central Iowa’s Cerro Gordo County found arsenic in 70 percent of the samples, while 38 percent registered more than the MCL for arsenic. Public drinking water is routinely tested and must meet MCL guidelines for the presence of arsenic. Private wells, however, are unregulated.

The new five-year study, supported by Center for Disease Control and Prevention, will test private wells in Cerro Gordo County for arsenic and other substances. Sophia Walsh, an environmental health specialist at the Cerro Gordo County Department of Health, says the project will test at least 50 private wells in the county over the next three years.

LACMRERS Director Doug Schnoebelen.

LACMRERS Director Doug Schnoebelen.

Schnoebelen says they’ve built a talented team, which includes researchers from the Cerro Gordo County Department of Health, the State Hygienic Lab at The University of Iowa, the Iowa Department of Natural Resources, and Shawver Well Company. “I’m excited about the strong and diverse team we’ve put together to tackle this difficult subject,” Schnoebelen says. “I’m fortunate to have worked with many of them on previous projects.”

Schnoebelen himself will be applying the water-quality analysis skills he uses as director of the Lucille A. Carver Mississippi Riverside Environmental Research Station (LACMRERS). His role with the project — providing sampling protocols and expertise on geochemistry and geochemical modeling — is a good fit, Schnoebelen says. “It’s not such a stretch as you might think,” he explains. “Analyzing the geochemistry, as well as the fate and transport of chemical species, involves many of the same principles, whether it’s groundwater or surface water.”

Walsh will contact homeowners, locate wells, and prepare the sampling team. Personnel at the State Hygienic Laboratory, including Lorelei Kurimski, Sherri Marine, Pam Mollenhauer, and Mike Wichman, will provide water sample analysis for the project. Along with arsenic, they will test for pH, temperature, and flow rate, as well as alkalinity, hardness, and more, and share these results with the team. The Shawver Well Company will collect rock samples from new wells; these samples will be analyzed for a correlation with high arsenic levels. Researchers hope to find a link between arsenic and other data to help well drillers find the best locations and depths for new wells.

“Our hope is that by year five, we will have an indicator or indicators of the presence of arsenic in groundwater that well drillers can look for when they are drilling new wells,” Walsh says. “The Department of Public Health will also update policies based on what we learn. … And of course, anything that we do find out will be shared with the public and other agencies that are dealing with the issue of arsenic in groundwater.”

Arsenic is not limited to Cerro Gordo County. “Arsenic has been found in the groundwater in many counties throughout Iowa,” Schnoebelen says. Rural well owners who are concerned should contact their county health department to get their well tested for a small fee. The State Hygienic Laboratory can also provide supplies and instructions to homeowners for water testing. If high levels of arsenic are present, a water treatment system, such as reverse osmosis, may be necessary.

To learn more about the project, visit the Cerro Gordo County Department of Public Health website:

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