‘Forever chemicals’ found in nearly half of Iowa treated drinking water samples so far

Per- and polyfluoroalkyl substances, or PFAS, have been found in nearly half of the treated drinking water samples taken from Iowa public water supplies so far, according to an Iowa Department of Natural Resources report released Thursday.

PFAS are a group of thousands of human-made chemicals that have been used to make materials resistant to heat, oil, stains, grease and water since the 1930s. They’re often called “forever chemicals” because their molecular structures are made of strong bonds, so they don’t degrade easily.

Humans can be exposed to the chemicals through their drinking water, food, consumer products and surroundings. Long-term exposure is linked to myriad negative health impacts, including cancer risks, reproductive effects, child development, hormones, immune systems and cholesterol levels.

In January 2020, the Iowa DNR published its PFAS Action Plan, a document outlining the department’s initial steps for tackling the emerging contaminant. Thursday’s report — written before the U.S. Environmental Protection Agency’s recently announced proposal for enforceable PFAS limits — reveals the department’s progress and findings after sampling the three most vulnerable tiers of public water supplies in Iowa.

Between October 2021 and December 2022, the Iowa DNR analyzed 126 treated water samples for 25 unique PFAS compounds. At least one compound was found in 41 percent of samples from 116 public water supplies in Iowa. PFAS concentrations in 15 samples surpassed the EPA’s previous health advisories.

“We didn't really know what to expect across the state,” said Corey McCoid, the Iowa DNR’s PFAS coordinator. “We knew we would find (PFAS). We just didn't know how much.”

Varying water sources, varying threats

Iowa’s public drinking water supplies can draw from deep wells that dip into aquifers, shallow wells stationed near waterways, and surface water from rivers, lakes and reservoirs. Thursday’s report showed that different water sources come with different PFAS risks.

Twenty-three public water supplies in Iowa wholly or partially rely on surface water, and several communities purchase water from these supplies. In untreated samples of the source water, six types of PFAS compounds were found at varying abundances — from some detected in 88 percent of the samples to others detected in only 9 percent.

Untreated groundwater from 128 wells, representing 100 public water supplies, generally had less PFAS detection. About a third of the samples contained at least one PFAS compound. But, in comparison to surface water, groundwater samples had a larger number of compounds and a larger variety of mixtures.

So far, the most elevated PFAS levels have been found in public water supplies near industrial areas, locations of fires or fire-training activities, and along the Mississippi River.

Operations permits have been revised for 20 public water supplies, including the Cedar Rapids Water Division, to include quarterly monitoring of treated drinking water as a result of the Iowa DNR sampling.

“The good news story that has come out from this is that a lot of the water supplies across the state are working as hard as they can to even analyze more wells and collect more information beyond what we did in our own sampling,” McCoid said.

Next steps

The Iowa DNR plans to complete reviews anywhere that continued sampling shows increasing PFAS concentrations. If the review reveals a PFAS source and a public health threat, the department — or an “evident and solvent” responsible party — may sample soil and groundwater to solidify the source.

The department just started sampling its fourth tier of susceptible water supplies and will continue its sampling plan over the next few years, along with required federal sampling of unregulated contaminants.

Enforcement of PFAS in drinking water will wait until the EPA’s long-awaited proposed drinking water limits are finalized.

“Once we have proposed rule and a final rule, (public water suppliers) can actually move forward with treatment,” McCoid said.

Brittney J. Miller is the Energy & Environment Reporter for The Gazette and a corps member with Report for America, a national service program that places journalists in local newsrooms to report on under-covered issues.

Comments: (319) 398-8370; brittney.miller@thegazette.com