EPA v. Yellowstone County MS4
Final Order With Penalty
Case summary
On June 23, 2026, Region 8 issued a CAFO to Yellowstone County to resolve an alleged violation for an unpermitted discharge from its Municipal Separate Storm Sewer System (MS4). EPA alleges that Yellowstone County violated the CWA by discharging stormwater runoff through an outfall at Five Mile Creek during the time where Yellowstone County was not covered under either Montana's Pollutant Discharge Elimination System, or EPA's National Pollutant Discharge Elimination System General Permit. Under the CAFO, Yellowstone County agreed to pay a $22,400 civil penalty to resolve the alleged violation.
Defendants (1)
- Yellowstone County CommissionersNamed in complaintNamed in settlement
Facilities (1)
YELLOWSTONE COUNTY/MDT SMALL MS-4
HWY RIGHT OF WAYS IN YELLOWSTONE COUNTY, BILLINGS, MT, 59107-5024
Registry ID: 110032592148
Statutes cited
- CWA 301/402 — NPDES Permit Violations
Enforcement conclusions (1)
Yellowstone County MS4entered 2026-06-23
Primary law: CWA
Federal penalty: $22,400
Timeline (5 milestones)
- 2026-06-23Complaint Filed/Proposed Order
- 2026-06-23Final Order Issued
- 2026-07-28Enforcement Action Data Entered
- 2026-07-28NPDES Closed
- 2026-07-28Enforcement Action Closed
Case metadata
- EPA activity ID
- 3605024855
- Case number
- 08-2026-0249
- Lead agency
- EPA
- EPA region
- 08
- Voluntary self-disclosure
- No
- Primary statute
- NPDES Permit Violations
Sourced verbatim from EPA ECHO Enforcement Case Report for case 08-2026-0249 . Bulk data: ICIS-FEC download summary.
This is legal information, not legal advice. Laws vary by jurisdiction and change frequently. Always verify current law with official sources and consult a licensed attorney in your jurisdiction for advice on your specific situation.