How many wastewater permits expire in California in 2027?

28 NPDES permits held by publicly owned wastewater treatment plants in California expire in 2027, covering a combined average flow of 57 MGD. The busiest month is Jul 2027 with 5 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 California in 2027?

Valencia Wwrp in Valencia, treating about 14.1 MGD under permit CA0054216, expiring Jun 2027.

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

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

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California wastewater permits expiring in 2027

Name: California NPDES permits expiring in 2027
Creator: Klarifi
License: https://klarifi.io/terms-of-service

28 NPDES permits · 57 MGD combined average flow

28 publicly owned wastewater treatment plants in California hold NPDES permits that expire during 2027, issued by California State Water Resources Control Board. 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:

2026 (20)2028 (24)All California NPDES permits →

Publicly owned wastewater treatment plants in California with NPDES permits expiring in 2027, from EPA ICIS-NPDES records. Refreshed on every release.
Facility	City	Avg flow (MGD)	NPDES permit	Expires	Technology	Violations (3y)
Los Coyotes Water Reclamation Plant	Cerritos	—	CA0054011	Jan 2027	Aerated lagoons	2
Mt View Sanitary Dist WWTF	Martinez	—	CA0037770	Jan 2027	Clarifiers, Uncovered lagoons, Biogas silos	6
Holtville City WWTP	Holtville	0.36	CA0104361	Feb 2027	Clarifiers	6
Long Beach Water Reclamation Plant	Long Beach	4.44	CA0054119	Mar 2027	—	5
Padre Dam WRF	Santee	—	CA0107492	Mar 2027	Uncovered lagoons, Biogas silos	5
Soscol WRF	Napa	—	CA0037575	Mar 2027	Aerated lagoons, Uncovered lagoons, Biogas silos, Biogas balloons	11
Aliso Creek Ocean Outfall	Dana Point	11.47	CA0107417	Apr 2027	Biogas silos	32
Dunaweal WWTP	Calistoga	—	CA0037966	Apr 2027	Clarifiers, Aerated lagoons, Uncovered lagoons	30
Lompoc Wastewater Plant	Lompoc	—	CA0048127	Apr 2027	Clarifiers, Aerated lagoons, Uncovered lagoons, Carrousels / oxidation ditches, Biogas silos	11
Corning Wastewater Treatment Plant	Corning	0.63	CA0004995	May 2027	Clarifiers, Aerated lagoons, Uncovered lagoons, Carrousels / oxidation ditches	681
Colusa WWTP	Colusa	0.46	CA0078999	May 2027	Clarifiers, Aerated lagoons, Uncovered lagoons	67
Hammonton Gold Village WWTP	Smartsville	0.01	CA0081574	May 2027	Uncovered lagoons	209
City Of San Leandro Water Pollution Control Plant - Treatment Wetland	San Leandro	—	CA0038881	May 2027	Clarifiers, Uncovered lagoons, Biogas silos, Biogas balloons	0
Valencia Wwrp	Valencia	14.1	CA0054216	Jun 2027	Biogas silos	5
Saugus Wwrp	Saugus	4.3	CA0054313	Jun 2027	Biogas silos	9
Chino	Chino	6.4	CA8000409	Jul 2027	Clarifiers, Biogas silos	519
Clear Creek WWTP	Anderson	5.67	CA0079731	Jul 2027	Clarifiers, Uncovered lagoons, Biogas silos	16
Nevada City Wastewater Treatment Plant	Nevada City	0.38	CA0079901	Jul 2027	Clarifiers	184
American Canyon Waste Water Treatment Facility	American Canyon	—	CA0038768	Jul 2027	Aerated lagoons, Uncovered lagoons	0
Central Contra Costa WWTF	Martinez	—	CA0037648	Jul 2027	Clarifiers, Uncovered lagoons	0
City Of Morro Bay Water Reclamation Facility	Morro Bay	2.74	CA3000002	Aug 2027	—	40
City Of Livermore Sewage Treatment Plant	Livermore	—	CA0038008	Aug 2027	Clarifiers, Uncovered lagoons, Biogas silos	7
Dublin-San Ramon WWTF	Pleasanton	—	CA0037613	Aug 2027	Clarifiers, Biogas silos	15
Mendocino City Csd	Mendocino	0.06	CA0022870	Sep 2027	Uncovered lagoons	2
Beaumont WWTF	Beaumont	3.54	CA0105376	Oct 2027	—	14
Summerland Sd WWTP	Summerland	0.06	CA0048054	Oct 2027	—	5
Calera Creek Wrp	Pacifica	1.91	CA0038776	Nov 2027	—	4
Healdsburg WWTF	Healdsburg	0.75	CA0025135	Nov 2027	Aerated lagoons, Uncovered lagoons	249

California permit renewals in 2027: 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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