California wastewater permits expiring in 2026
20 NPDES permits · 170 MGD combined average flow
20 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 | Technology | Violations (3y) |
|---|---|---|---|---|---|---|
| Shasta Lake WWTF | Shasta Lake | 0.43 | CA0079511 | Jan 2026 | Clarifiers, Aerated lagoons, Uncovered lagoons, Carrousels / oxidation ditches | 30 |
| Harrah'S Northern California WWTP | Ione | 0.01 | CA0049675 | Feb 2026 | — | 57 |
| Manteca Wwqcf | Manteca | 5.18 | CA0081558 | Mar 2026 | Clarifiers, Uncovered lagoons, Biogas silos | 7 |
| Uc Davis WWTP | Davis | 1.47 | CA0077895 | Mar 2026 | — | 11 |
| Turlock Rwqcf | Turlock | — | CA0078948 | Mar 2026 | Clarifiers, Covered lagoons, Uncovered lagoons, Biogas silos | 28 |
| City Of St Helena Wastewater Treatment Plant | Saint Helena | — | CA0038016 | May 2026 | Aerated lagoons | 198 |
| Olivehurst WWTF | Olivehurst | 1.99 | CA0077836 | May 2026 | Clarifiers, Aerated lagoons, Uncovered lagoons, Carrousels / oxidation ditches | 24 |
| Anchor Bay WWTF | Anchor Bay | 0.0064 | CA0024040 | May 2026 | Aerated lagoons | 110 |
| Malibu Mesa Wrp | Malibu | — | CA0059099 | May 2026 | Clarifiers | 0 |
| Sacramento County Wastewater Treatment Plant | Elk Grove | — | CA0077682 | May 2026 | Clarifiers, Uncovered lagoons, Carrousels / oxidation ditches, Biogas silos, Biogas balloons | 6 |
| South Bay International WWTP | San Diego | 29 | CA0108928 | Jun 2026 | Clarifiers, Biogas silos | 3159 |
| City Of Paso Robles Wastewater Treatment Facility | Paso Robles | 2.27 | CA0047953 | Jun 2026 | Clarifiers, Uncovered lagoons, Biogas silos | 17 |
| Brawley Wastewater Treatment Plant | Brawley | — | CA0104523 | Jun 2026 | Clarifiers, Uncovered lagoons | 25 |
| Lavwma Export And Storage Facilities | Pleasanton | — | CA0038679 | Jun 2026 | Uncovered lagoons | 76 |
| Orange County Sanitation District Plant 1 | Fountain Valley | 77.37 | CA0110604 | Jul 2026 | Clarifiers | 0 |
| Whittier Narrows Water Reclamation Plant | South El Monte | 10.24 | CA0053716 | Jul 2026 | — | 14 |
| Terminal Island Treatment Plant | San Pedro | 9.8 | CA0053856 | Jul 2026 | — | 17 |
| La Co., Sanitation Dist | Pomona | — | CA0053619 | Jul 2026 | Uncovered lagoons | 11 |
| Sewerage Commission - Oroville Region | Oroville | 3.4 | CA0079235 | Sep 2026 | Clarifiers, Aerated lagoons, Uncovered lagoons, Biogas silos | 0 |
| San Jose Creek Water Reclamation Plant | Whittier | 28.38 | CA0053911 | Nov 2026 | — | 26 |
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 September 11, 2026.