A new analysis of drinking water systems shows communities in five Midwest states have legal but potentially worrying levels of nitrates. The Environmental Working Group (EWG) found nitrate levels in Iowa, Illinois, Kansas, and Oklahoma are trending up.

Anne Schechinger, senior economics analyst for EWG and author of the report, says heavy rains may account for the spikes seen in some states during certain years. She also found nitrate problems are more frequent in communities with fewer residents, which sometimes have water supplies close to farm fields.

“Small systems are more likely to be rural and they’re more likely to be ground-water systems,” Schechinger says. “These smaller systems are way less likely to have nitrate removal treatment systems.”

Schechinger says runoff from agricultural lands contributes to nitrates in drinking water supplies.

She called out Nebraska for working creatively to slow the problem.

In Hastings, Nebraska, a new system removes nitrates before they enter the drinking water supply.

“We’ve actually seen it clean up that area that we’re getting our water from,” says city environmental director Marty Stagne. “It’s actually cleaned up slightly faster than what we anticipated.”

Stange says a treatment system that would remove nitrates from drinking water before it is pumped out to users was prohibitively expensive for the community of 25,000 people. Instead, certain wells collect potentially polluted water, act as a filter and prevent the nitrates from moving on. The nutrient can be repurposed as fertilizer, which is often why it was applied to the land in the first place, and the clean water is then reinjected into the aquifer, which goes on to supply the wells that do provide drinking water.

Read the full article about polluted drinking water by Amy Mayer at Harvest Public Media.