Water Quality | Supplemental MPDES Small MS4 Rulemaking | Comment Period Ends June 5, 2026 | Public Hearing June 4, 2026
On April 24, 2026, the Montana Department of Environmental Quality (DEQ) initiated rulemaking on proposed amendments to ARM 17.30.201, 17.30.1102, and 17.30.1107 pertaining to Montana Pollutant Discharge Elimination System (MPDES) permits, definitions, and designation procedures for small municipal separate storm sewer systems (MS4s).
On April 27, 2026, the department determined that the document entitled “MPDES MS4 Designation: City of Belgrade (DEQ 2026)” had not been posted to the department's website as indicated in MAR Notice No. 2026-489.1. On April 28, 2026, the department posted the document on its website at https://deq.mt.gov/News/publiccomment-folder/WPB-MPDES-Small-MS4-Rulemaking. To ensure adequate opportunity for public notice and comment, the department is rescheduling the public hearing and extending the public comment period as set forth below.
The proposed rulemaking updates MPDES small municipal separate storm sewer system (MS4) rule language to reflect current federal terminology and updates rule references and jurisdiction listings based on the most recent decennial census data. The amendments replace the term “urbanized area” with current federal terminology and clarify which jurisdictions meet automatic designation thresholds or are identified under existing designation criteria based on current census classifications. The amendments do not alter the structure or effect of the designation or waiver provisions and do not impose new fees or new permit obligations on private entities.
Associated materials and links:
- MAR Notice No. 2026-489.1 (Notice of Proposed Rulemaking; Montana Administrative Register, Issue No. 8, April 24, 2026)
- MAR Notice No. 2026-489.2 (Supplemental Notice of Proposed Rulemaking, Montana Administrative Register, Issue No. 9, May 8, 2026)
- MPDES MS4 Designation City of Belgrade
How to submit public comments:
Mail comments to:
Department of Environmental Quality
Legal Unit
P.O. Box 200901
Helena, Montana 59620-0901
Or e-mail comments to: DEQMAR489@mt.gov
Comment period ends on June 5, 2026, at 5:00 p.m.
Public hearing information:
June 4, 2026, at 10:00 a.m.
Wilderness Room
2401 Colonial Drive
Helena, Montana
Or, join the hearing online via Zoom:
Webinar ID: 843 9400 1081
Passcode: 815267
Telephone: (213) 338-8477; (206) 337-9723; or (646) 558-8656
Tags: Public Comment, Water, Public Meeting and Rule Making