Who issues NPDES permits in Montana?

Montana Department of Environmental Quality issues and enforces NPDES permits for wastewater discharges in Montana. Klarifi tracks 102 permits held by publicly owned treatment plants in the state.

How many NPDES permits in Montana are expired or administratively continued?

55 permits are administratively continued (the plant applied for renewal and the old permit stays in force) and 3 are recorded as expired, out of 102 permits tracked. 43 are effective.

How many Montana wastewater permits come up for renewal soon?

11 in 2026, 27 in 2027 and 5 in 2028. Each year has its own renewal calendar with the plants listed.

How do I look up an NPDES permit number?

Enter the permit number (two letters and seven characters, for example TX0021873) or the plant name in the lookup on the NPDES page; each result opens the plant profile with status, expiry, design flow and the three-year violation count.

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NPDES permits in Montana

Name: NPDES permits held by wastewater treatment plants in Montana
Creator: Klarifi
License: https://klarifi.io/terms-of-service

102 permits held by publicly owned wastewater treatment plants · issued by MDEQ

Effective

Administratively continued

Expired

Total tracked

102

Montana Department of Environmental Quality (MDEQ) runs the NPDES program in Montana under delegation from EPA Region 8, issuing and enforcing the discharge permits listed here. Klarifi tracks 102 permits held by publicly owned treatment plants in the state, with status, expiry, design flow and three-year compliance for each. Agency website →

An NPDES permit runs for five years. To keep discharging, a plant must apply for renewal at least 180 days before the expiry date, and the renewed permit usually arrives with tighter effluent limits, new monitoring requirements or a compliance schedule. That is why the year a permit expires is the year a plant starts budgeting for upgrades: nutrient removal, disinfection, capacity or controls.

Permit renewals by year

2026: 11 permits →2027: 27 permits →2028: 5 permits →

2029: 3 permits

2030: 2 permits

2031: 1 permits

Largest permit holders in Montana

The 25 largest publicly owned wastewater treatment plants in Montana by permitted design flow, with NPDES permit number, status and expiry. Source: EPA ICIS-NPDES via Klarifi.
Facility	City	Avg flow (MGD)	Design (MGD)	NPDES permit	Status	Expires	Violations (3y)
City Of Billings Wastewater Treatment Plant	Billings	20.31	—	MTR000459	Effective	Jan 2028	7
City Of Missoula WWTF No Exposure	Missoula	7.52	12	MT0022594	Administratively continued	Apr 2020	7
Crow Agency Lagoon	Crow Agency	—	11.21	MTG589009	Effective	Mar 2027	850
City Of Bozeman WWTP	Bozeman	7.35	—	MT0022608	Administratively continued	May 2017	0
City Of Kalispell WWTP	Kalispell	3.21	—	MT0021938	Administratively continued	Jul 2020	11
City Of Helena WWTP	Helena	3.14	—	MT0022641	Administratively continued	Sep 2017	37
Lewistown WWTP	Lewistown	2.38	2.5	MT0020044	Administratively continued	Aug 2017	32
Water Reclamation Facility	Livingston	0.69	2.18	MT0020435	Administratively continued	Oct 2021	0
Miles City WWTP	Miles City	1.11	1.98	MT0020001	Administratively continued	Sep 2023	3
Havre WWTF	Havre	1.64	—	MT0022535	Administratively continued	Aug 2026	0
City Of Glendive Water Resource & Recovery Facility	Glendive	0.84	1.6	MT0021628	Effective	May 2027	3
Red Lodge WWTF	Red Lodge	0.57	1.2	MT0020478	Effective	Apr 2027	3
Town Of Belt - WWTP	Belt	—	0.9	MT0021571	Administratively continued	Jun 2022	92
City Of Hamilton Wastewater Treatment Plant	Hamilton	0.79	—	MT0020028	Effective	Dec 2026	0
Deer Lodge WWTP	Deer Lodge	0.72	—	MT0022616	Administratively continued	Feb 2018	3
Bigfork County Water And Sewer	Bigfork	0.32	0.69	MT0020397	Administratively continued	Apr 2023	1
City Of Glasgow Parks Maintenance Bldg	Glasgow	0.66	—	MT0021211	Effective	Nov 2026	21
Anaconda-Deer Lodge County Wastewater Holding Ponds And Ip Beds Facility	Anaconda	0.66	—	MTX000231	Expired	May 2024	0
City Of Polson WWTP	Polson	0.5	0.65	MT0020559	Administratively continued	Aug 2024	0
City Of Cut Bank WWTF	Cut Bank	0.17	0.64	MT0020141	Administratively continued	Feb 2017	42
Three Forks WWTF	Three Forks	0.31	0.61	MT0020401	Effective	Apr 2027	5
Town Of Poplar WTP	Poplar	0.59	0.6	MT0030597	Administratively continued	Jun 2025	176
City Of Shelby Wastewater Lagoons	Shelby	0.53	—	MT0031488	Administratively continued	Feb 2025	20
City Of Belgrade- Belgrade Wastewater Treatment Plant	Belgrade	0.5	—	MTX000116	Administratively continued	Sep 2023	30
Gardiner Wastewater Treatment Facility	Gardiner	0.13	0.47	MT0022705	Effective	Sep 2027	119

All 102 plants in Montana →

NPDES permits in Montana: questions

Sources and methodology

Flow, permit and violation figures come from the EPA's ICIS-NPDES discharge monitoring records. Population served comes from the Clean Watersheds Needs Survey 2022. Treatment structures are identified by Klarifi's review of aerial imagery, and capital improvement projects are extracted from published municipal budget documents. Violations are counted over the last three years of monitoring reports.

Data refreshed September 11, 2026.

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