DEQ outlines PFAS detections, asks committee to adopt EPA drinking-water rule; vote deferred

Tyler Fortunati, chief of the Drinking Water Bureau for the Idaho Department of Environmental Quality, told the Senate Health and Welfare Committee on Feb. 7, 2025, that DEQ is asking the committee to adopt the U.S. Environmental Protection Agency’s finalized drinking-water rule for per- and polyfluoroalkyl substances, but that the committee would not vote on the pending state rule until next week.

Fortunati said the EPA finalized a PFAS drinking-water rule in April 2024 that sets maximum contaminant levels for six PFAS chemicals and imposes monitoring, reporting and compliance schedules for public water systems. "Water systems are required to complete initial monitoring ... by April of 2027," Fortunati said, and systems would have to come into compliance with the maximum contaminant levels by April 2029. He added that public-notification requirements under the rule begin in 2029 and that consumer-confidence-report language would start in April 2027.

The presentation summarized three sampling efforts affecting Idaho. The Department of Defense sampled its installations and found PFAS at Mountain Home Air Force Base and Gowen Field; Mountain Home had PFAS detections in multiple public-system sources in 2016 and installed treatment on Well No. 4 in 2018. "That well ... produces 1,300 gallons per minute," Fortunati said; he said initial installation cost at that well was $1,360,000 with O&M costs of about $100,000 at the time, and that the source was taken offline in 2020.

Fortunati described EPA’s unregulated contaminant monitoring program (the fifth iteration, 2023–2025), under which EPA selected 61 Idaho public water systems to sample for 29 PFAS analytes. To date, 41 of those systems had reported results to EPA and seven had detections; Fortunati said one system in the Boise regional area reported results that would exceed the EPA maximum contaminant level.

Separately, DEQ’s voluntary sampling project, funded by EPA emerging-contaminant grants and begun in April 2021, has sampled 381 of Idaho’s roughly 3,219 active public-water sources (about 12%). Fortunati said DEQ found 66 detections among those samples (about a 17% detection rate by source). At the system level, DEQ sampled 203 of about 2,016 regulated public water systems (about 10%), and 58 of those systems had detections (about a 28% detection rate by system); the largest detection Fortunati reported was 42.2 parts per trillion.

Fortunati said DEQ has identified 14 systems with one or more sources that could potentially exceed the EPA maximum contaminant level; 25 sources across those systems are impacted and 11 sources had two or more PFAS chemicals above the maximum contaminant level. He said DEQ is sampling raw source water (pre-treatment) and offers confirmation and expanded sampling if a system requests it.

To help systems pay for mitigation, Fortunati described the State Revolving Fund (SRF) capitalization for PFAS and related emerging-contaminant work. He said the SRF has approximately $7,600,000 available annually (fiscal years 2023–2027) for public drinking water systems and an additional $1,000,000 for wastewater systems; systems must submit a letter of interest and document a PFAS issue to get on the potential funding list. Fortunati said the current LOI cycle just closed and the next cycle will start in October.

Senator Maryanne Wintrow (committee member) pressed Fortunati on treatment and rural impacts. "Maybe you can talk a little bit about ... what is the treatment process like, if they're above the limits," Wintrow said. Fortunati said treatment (for example, the activated-carbon or ion-exchange systems used at Mountain Home) is one mitigation option; others include developing a new source, taking a contaminated source offline, or interconnecting with another system. On rural systems, Fortunati said the same options exist but noted consolidation or interconnection may be more logistically challenging in remote areas and that cost impacts depend on concentration, required mitigation and number of users.

Fortunati also said DEQ notifies the public water system and the local health district when DEQ sampling identifies detections. He added that while DEQ provides communication templates for systems, mandatory public notification under the EPA rule starts in 2029; before that, DEQ does not have a regulation compelling public-notification beyond its sampling outreach.

After the presentation Fortunati asked the committee to support adoption of the cited docket for Idaho rules; the committee did not vote on the pending rule that day. "We don't have the pending rule before us today, so we'll vote on that next week," the chair said.

As presented, the docket references and sampling figures are those Fortunati provided to the committee; DEQ and EPA datasets would be the primary sources for any follow-up reporting or verification.