How many wastewater permits expire in Idaho in 2026?

6 NPDES permits held by publicly owned wastewater treatment plants in Idaho expire in 2026, covering a combined average flow of 2 MGD. The busiest month is Dec 2026 with 2 expiries.

What happens when an NPDES permit expires?

The plant must have applied for renewal at least 180 days before the expiry date. If the agency has not reissued the permit by then, the old permit is administratively continued and stays enforceable. The reissued permit typically carries updated effluent limits based on the latest water-quality standards, which is what drives upgrade projects.

Which is the largest plant with a permit expiring in Idaho in 2026?

Salmon Sewage Lagoon in Salmon, treating about 1.09 MGD under permit ID0020001, expiring May 2026.

How do I get contacts for the plants on this list?

Every plant links to its profile with flow, permit and compliance data. Treatment technology and verified decision-maker contacts for each plant, and the same list for every state and year, are available in Klarifi with a free account.

Try for free Log in

Idaho wastewater permits expiring in 2026

Name: Idaho NPDES permits expiring in 2026
Creator: Klarifi
License: https://klarifi.io/terms-of-service

6 NPDES permits · 2 MGD combined average flow

6 publicly owned wastewater treatment plants in Idaho hold NPDES permits that expire during 2026, issued by Idaho Department of Environmental Quality. The table lists each plant with its permit number, expiry month, average flow, treatment technology and three-year violation count, in order of expiry.

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.

Other years:

2028 (7)All Idaho NPDES permits →

Publicly owned wastewater treatment plants in Idaho with NPDES permits expiring in 2026, from EPA ICIS-NPDES records. Refreshed on every release.
Facility	City	Avg flow (MGD)	NPDES permit	Expires	Violations (3y)
White Bird Sewage Treatment System	White Bird	—	ID0024252	Mar 2026	11
Richfield WWTP	Richfield	0.04	ID0021211	Apr 2026	19
Salmon Sewage Lagoon	Salmon	1.09	ID0020001	May 2026	2
Cottonwood STP	Cottonwood	0.22	ID0021849	Aug 2026	22
Riverside Water And Sewer District WWTP	Orofino	0.28	ID0024503	Dec 2026	4
Ahsahka Wastewater Treatment Plant	Orofino	0.02	ID0025224	Dec 2026	0

Idaho permit renewals in 2026: 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 October 26, 2026.

Wastewater terms: NPDES permit · POTW · Biological nutrient removal · Tertiary treatment · Filter press · FOG · all terms

Cite this page

Journalists, researchers and educators are welcome to quote these figures. Please credit Klarifi as the source and link to this page.

Klarifi. “NPDES permits expiring in 2026: Idaho wastewater plants.” Updated October 26, 2026. https://klarifi.io/facilities/idaho/permits-expiring/2026

Need a custom cut of the data for a state, a county or a list of plants? Email info@klarifi.io.

Try Klarifi for free

Create your own trial account and explore how Klarifi can help you.

Try for free