For HIDDEN LAKE YELLOWSTONE COUNTY W AND S D (PWSID MT0003374) — BILLINGS, MT · serving 350 people
We don't see UCMR 5 detections above the federal MCL on file for HIDDEN LAKE YELLOWSTONE COUNTY W AND S D. Many small systems were never required to sample under UCMR 5, so "no detections on file" can mean "not yet tested" rather than "clean." The claim windows have closed; what applies now is monitoring and the April 2029 compliance date below.
PFAS compounds detected: 0 · Max PFOA: — ppt · Max PFOS: — ppt
The DuPont/Chemours/Corteva window ($1.185B) closed June 30, 2026, the 3M Phase 2 Action Fund ($10.5–12.5B) on July 31, and the Special Needs Fund on August 1. Systems that did not file are no longer eligible for a share. For systems that did, first distributions are expected mid-to-late 2026, and the Supplemental Fund reimburses eligible treatment costs through December 2030. What still applies to every system over the limit is the April 2029 EPA compliance deadline.
Already filed — directly or through counsel? You're set; do not file again. Duplicate submissions can delay processing. If you're unsure which form is on file (the earlier registration/Phase 1 claim vs. the Phase 2 Action Fund claim), confirm with the settlement administrator.
Military transition off fluorinated foam completes
Due October 1, 2026
The congressionally mandated deadline for the Defense Department to stop using fluorinated AFFF, after final waiver extensions, is October 1, 2026. Disposal, replacement-foam, and site-investigation activity around installations accelerates into this date.
Why it matters: Systems near military installations see the fastest-moving PFAS investigation and remediation activity around this transition.
Read the DOD PFAS guidance →4 ppt compliance date for public water systems
Due April 26, 2029
EPA reaffirmed the 4 ppt MCLs for PFOA and PFOS in May 2026 — those limits are final and unchanged. Compliance is due April 2029. A proposed rule (docket EPA-HQ-OW-2025-1742, comments closed July 20, 2026) would let eligible systems request a two-year extension to 2031 — proposed, not final.
Why it matters: Systems above 4 ppt without treatment in place face SDWA violations from April 2029.
Read EPA's extension proposal →Ongoing treatment-cost reimbursement window
Weekly email covering settlement distributions, the Supplemental Fund reimbursement window through 2030, EPA's pending rules, and grant rounds for treatment funding. The full documentation checklist — the same records SRF and EC-SDC applications ask for — is below on this page.
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Kept for reference. The settlement filing windows have closed, but the same records support state revolving fund and EC-SDC grant applications, and section 3 (treatment costs) is still the one that takes longest to pull together.
Due December 31, 2030 · Fund: Per settlement terms
Systems that completed baseline testing under the 3M and DuPont settlements can seek reimbursement for eligible future treatment and compliance costs through December 31, 2030. Reimbursement runs on documentation — keep treatment invoices, O&M records, and media-changeout logs current. Confirm your system's specific terms with the settlement administrator.
If you miss it: Eligible treatment costs go unreimbursed.
Treatment & remediation cost claims — closed
Closed July 31, 2026 · Fund: $10.5–12.5B
Public water systems with confirmed PFAS detections had until July 31, 2026 to file via the official PFAS Water Settlement portal. The fund — the largest PFAS settlement pool in U.S. history — has moved to allocation: first Phase 2 distributions are expected mid-to-late 2026, staggered through the 2030s.
If you didn't file: Systems that did not file forfeited their share of the 3M fund and waived future direct-action rights against 3M for PFAS.
Check claim status with the administrator →Action Fund claims — closed
Closed June 30, 2026 · Fund: $1.185B
Phase 2 water systems (those serving >3,300 people, or those that detected PFAS more recently) had until June 30, 2026 to submit Action Fund claim forms covering remediation and treatment costs. The window is closed; distributions follow the same mid-2026-onward schedule as the 3M fund.
If you didn't file: Systems that did not file forfeited their share of the DuPont/Chemours/Corteva treatment fund.
Check claim status with the administrator →Disadvantaged-system applications — closed
Closed August 1, 2026 · Fund: Discretionary
The supplemental fund for systems facing capacity, affordability, or technical barriers closed to applications August 1, 2026. Awards are discretionary and determinations come from the settlement administrator.
If you didn't file: Systems that did not apply forfeited the supplemental allocation reserved for disadvantaged communities.
Check claim status with the administrator →