Dangerous chemicals, known as PFAS, have been detected in one of Sioux City’s drinking water sources, with contamination levels that now warrant a health advisory.

In January, the Iowa Department of Natural Resources detected the presence of per-and polyfluoroalkyl substances (PFAS) at the Southbridge Water Treatment plant. At the time, those levels did not meet the Environmental Protection Agency’s threshold for a health advisory.

But, the EPA drastically lowered those thresholds this summer. They dropped from 70 parts per trillion to 0.004 parts per trillion for Perfluorooctane Sulfonate (PFOS) and 0.002 parts per trillion for Perfluorooctanoic Acid (PFOA). More than a dozen Iowa communities’ water sources surpass this level.

Sioux City’s levels are at 4.4 parts per trillion for PFOS and 5.7 for PFOA. The contamination likely came from a nearby Iowa Air National Guard Base, where levels in groundwater were detected as high as 8,610 parts per trillion nearly three years ago. The chemicals, existent in firefighting foams, are believed to have migrated off-site and into the drinking water.

Read the entire article here.

Reporting by Iowa Public Radio’s Kendall Crawford.