Who issues NPDES permits in Washington?

Washington State Department of Ecology issues and enforces NPDES permits for wastewater discharges in Washington. Klarifi tracks 125 permits held by publicly owned treatment plants in the state.

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

58 permits are administratively continued (the plant applied for renewal and the old permit stays in force) and 3 are recorded as expired, out of 125 permits tracked. 52 are effective.

How many Washington wastewater permits come up for renewal soon?

14 in 2026, 2 in 2027 and 1 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 Washington

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

125 permits held by publicly owned wastewater treatment plants · issued by Ecology

Effective

Administratively continued

Expired

Total tracked

125

Washington State Department of Ecology (Ecology) runs the NPDES program in Washington under delegation from EPA Region 10, issuing and enforcing the discharge permits listed here. Klarifi tracks 125 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: 14 permits →

2027: 2 permits

2028: 1 permits

2029: 11 permits

2030: 19 permits

2031: 6 permits

Largest permit holders in Washington

The 25 largest publicly owned wastewater treatment plants in Washington 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)
Colville WWTP	Colville	0.62	73.1	WA0022616	Administratively continued	Jul 2020	0
Three Rivers Regional WWTP	Longview	—	52	WA0037788	Administratively continued	Feb 2026	0
Ellensburg WWTP	Ellensburg	—	32	WA0024341	Effective	Dec 2023	0
Riverside Park Water Reclamation Facility	Spokane	31.72	—	WA0024473	Effective	Aug 2027	4
Medical Lake WWTP	Medical Lake	0.27	24.6	WA0021148	Administratively continued	Jul 2019	13
Richland City Wastewater Lab	Richland	6.31	22.8	WA0020419	Expired	Sep 2021	0
Sunnyside STP	Sunnyside	1.31	22.4	WA0020991	Administratively continued	Jan 2020	1
Port Angeles WWTP	Port Angeles	—	21.6	WA0023973	Administratively continued	Jan 2021	0
Pullman City Muni SW	Pullman	2.13	21.5	WA0044652	Administratively continued	May 2019	1
Chambers Creek WWTP	University Place	17.07	—	WAR000727	Effective	Dec 2029	0
Wenatchee Wastewater Treatment Plant	Wenatchee	—	16.5	WA0023949	Administratively continued	Aug 2015	10
Clarkston WWTP	Clarkston	0.71	15.6	WA0021113	Expired	Apr 2021	0
Othello STP	Othello	1.27	10	WA0022357	Effective	Sep 2025	85
Palouse Wastewater Treatment Plant	Palouse	0.04	8.4	WA0044806	Administratively continued	Mar 2020	21
Port Of Sunnyside Industrial WWTF	Sunnyside	1.17	8.1	WA0052426	Administratively continued	Aug 2019	79
Colfax Wastewater Treatment Plant	Colfax	—	4.8	WA0020613	Administratively continued	Oct 2015	4
Newport WWTP	Newport	—	4	WA0022322	Administratively continued	Apr 2013	21
Okanogan WWTP	Okanogan	0.15	3.78	WA0022365	Effective	Sep 2030	1
Omak Wastewater Treatment Plant	Omak	0.53	3.78	WA0020940	Administratively continued	Dec 2020	0
Oroville Wastewater Treatment Plant	Oroville	—	3.5	WA0022390	Administratively continued	Nov 2019	0
Ilwaco Wastewater Treatment Plant	Ilwaco	0.15	3.03	WA0023159	Effective	Aug 2030	4
Kittitas POTW	Kittitas	—	2.7	WA0021253	Effective	Mar 2029	25
Camas STP	Camas	2.62	—	WA0020249	Effective	Jul 2030	19
Leavenworth STP	Leavenworth	—	2.52	WA0020974	Administratively continued	Aug 2020	0
Bingen POTW	Bingen	—	2.4	WA0022373	Administratively continued	Jun 2019	13

All 125 plants in Washington →

NPDES permits in Washington: 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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