California wastewater permits expiring in 2026
15 NPDES permits · 150 MGD combined average flow
15 publicly owned wastewater treatment plants in California hold NPDES permits that expire during 2026, 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.
| Facility | City | Avg flow (MGD) | NPDES permit | Expires | Violations (3y) |
|---|---|---|---|---|---|
| Shasta Lake WWTF | Shasta Lake | 0.86 | CA0079511 | Jan 2026 | 31 |
| Harrah'S Northern California WWTP | Ione | 0.01 | CA0049675 | Feb 2026 | 56 |
| Turlock Rwqcf | Turlock | — | CA0078948 | Mar 2026 | 28 |
| City Of St Helena Wastewater Treatment Plant | Saint Helena | — | CA0038016 | May 2026 | 198 |
| Olivehurst WWTF | Olivehurst | 1.99 | CA0077836 | May 2026 | 25 |
| Donner Summit WWTF | Soda Springs | 0.19 | CA0081621 | May 2026 | 23 |
| Anchor Bay WWTF | Anchor Bay | 0.02 | CA0024040 | May 2026 | 107 |
| Malibu Mesa Wrp | Malibu | — | CA0059099 | May 2026 | 0 |
| South Bay International WWTP | San Diego | 28.5 | CA0109045 | Jun 2026 | 2645 |
| Brawley Wastewater Treatment Plant | Brawley | 2.55 | CA0104523 | Jun 2026 | 24 |
| City Of Paso Robles Wastewater Treatment Facility | Paso Robles | 2.54 | CA0047953 | Jun 2026 | 15 |
| Orange County Sanitation District Plant 1 | Fountain Valley | 99.43 | CA0110604 | Jul 2026 | 0 |
| Whittier Narrows Water Reclamation Plant | South El Monte | 10.72 | CA0053716 | Jul 2026 | 14 |
| La Co., Sanitation Dist | Pomona | — | CA0053619 | Jul 2026 | 11 |
| Sewerage Commission - Oroville Region | Oroville | 3.13 | CA0079235 | Sep 2026 | 0 |
California 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 · Equalization tank · Centrate · 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: California wastewater plants.” Updated October 26, 2026. https://klarifi.io/facilities/california/permits-expiring/2026Need a custom cut of the data for a state, a county or a list of plants? Email info@klarifi.io.