California wastewater permits expiring in 2027
27 NPDES permits · 73 MGD combined average flow
27 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.
| Facility | City | Avg flow (MGD) | NPDES permit | Expires | Violations (3y) |
|---|---|---|---|---|---|
| Mt View Sanitary Dist WWTF | Martinez | — | CA0037770 | Jan 2027 | 6 |
| Holtville City WWTP | Holtville | 0.37 | CA0104361 | Feb 2027 | 6 |
| Long Beach Water Reclamation Plant | Long Beach | 6.98 | CA0054119 | Mar 2027 | 5 |
| Padre Dam WRF | Santee | — | CA0107492 | Mar 2027 | 5 |
| Soscol WRF | Napa | — | CA0037575 | Mar 2027 | 12 |
| Aliso Creek Ocean Outfall | Dana Point | 12.64 | CA0107611 | Apr 2027 | 34 |
| Lompoc Wastewater Plant | Lompoc | 6.37 | CA0048127 | Apr 2027 | 11 |
| Dunaweal WWTP | Calistoga | — | CA0037966 | Apr 2027 | 26 |
| Corning Wastewater Treatment Plant | Corning | 0.61 | CA0004995 | May 2027 | 681 |
| Colusa WWTP | Colusa | 0.55 | CA0078999 | May 2027 | 67 |
| Hammonton Gold Village WWTP | Smartsville | 0.01 | CA0081574 | May 2027 | 209 |
| Valencia Wwrp | Valencia | 15.64 | CA0054216 | Jun 2027 | 5 |
| Saugus Wwrp | Saugus | 3.87 | CA0054313 | Jun 2027 | 9 |
| Chino | Chino | 10.94 | CA8000409 | Jul 2027 | 519 |
| Clear Creek WWTP | Anderson | 6.72 | CA0079731 | Jul 2027 | 16 |
| Bear Valley Water District | Bear Valley | 0.85 | CA0085146 | Jul 2027 | 7 |
| Nevada City Wastewater Treatment Plant | Nevada City | 0.41 | CA0079901 | Jul 2027 | 181 |
| American Canyon Waste Water Treatment Facility | American Canyon | — | CA0038768 | Jul 2027 | 0 |
| Central Contra Costa WWTF | Martinez | — | CA0037648 | Jul 2027 | 0 |
| City Of Morro Bay Water Reclamation Facility | Morro Bay | — | CA3000002 | Aug 2027 | 18 |
| City Of Livermore Sewage Treatment Plant | Livermore | — | CA0038008 | Aug 2027 | 7 |
| Dublin-San Ramon WWTF | Pleasanton | — | CA0037613 | Aug 2027 | 15 |
| Mendocino City Csd | Mendocino | 0.09 | CA0022870 | Sep 2027 | 2 |
| Beaumont WWTF | Beaumont | 3.44 | CA0105376 | Oct 2027 | 12 |
| Summerland Sd WWTP | Summerland | 0.08 | CA0048054 | Oct 2027 | 5 |
| Calera Creek Wrp | Pacifica | 2.59 | CA0038776 | Nov 2027 | 4 |
| Healdsburg WWTF | Healdsburg | 1.14 | CA0025135 | Nov 2027 | 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 October 26, 2026.
Wastewater terms: NPDES permit · POTW · Biological nutrient removal · Tertiary treatment · Centrate · Ozonation · 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 2027: California wastewater plants.” Updated October 26, 2026. https://klarifi.io/facilities/california/permits-expiring/2027Need a custom cut of the data for a state, a county or a list of plants? Email info@klarifi.io.