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Wastewater treatment plants in California

192 facilities · 1,181 MGD combined flow

Klarifi tracks 192 publicly owned wastewater treatment plants in California with a combined average flow of 1,181 MGD, serving about 20,105,644 residents. 75 plants treat more than 1 MGD and 20 more than 10 MGD; 99 use lagoon systems and 74 have digesters or biogas infrastructure. The largest is Hyperion Treatment Plant in Playa Del Rey at 222.56 MGD. 15 NPDES permits expire this year and 27 next year.

Every plant below links to a profile with average and design flow, the NPDES permit and its expiry, a three-year compliance snapshot and the capital projects planned in its city. Treatment technology and verified contacts are shown with a free Klarifi account.

192 plant locations in California; dot size follows average flow. Boundaries: U.S. Census Bureau.

NPDES permits and renewals in California

Every plant discharges under an NPDES permit that is renewed every five years, usually with tighter limits. The renewal year is the year a plant budgets for upgrades.

All NPDES permits in California →15 permits expiring in 2026 →27 permits expiring in 2027 →24 permits expiring in 2028 →Find plants near you on the map →

Largest wastewater treatment plants in California

The 10 largest publicly owned wastewater treatment plants in California by average flow, with NPDES permit, expiry and three-year violation count. Source: EPA ICIS-NPDES via Klarifi.
FacilityCityAvg flow (MGD)Design (MGD)NPDES permitExpiresViolations (3y)
Hyperion Treatment PlantPlaya Del Rey222.56450CA0109991Apr 202842
Joint Water Pollution Control PlantCarson154.69400CA0053813Jun 202819
Point Loma Wastewater Treatment PlantSan Diego140.8240CA0107409Apr 20311689
Orange County Sanitation District Plant 1Fountain Valley99.43332CA0110604Jul 20260
Ccsf- Southeast Water Pollution Control PlantSan Francisco72.75400CA0037664Sep 201810
Stockton RwcfStockton28.9455CA0079138Jul 203061
South Bay International WWTPSan Diego28.518CA0109045Jun 20262645
Riverside City, Water Quality ControlRiverside27.9746CA0105350Oct 20182
Encina Water Pollution Control FacilityCarlsbad23.63—CAL107395Dec 203011
Colton/san Bernardino Stp, RixColton20.7940CA8000304Jul 20180

Treatment technology for each plant is shown with a free Klarifi account. Create one →

California plants by treatment technology

All 192 plants in California

FacilityCityFlow (MGD)
Hyperion Treatment PlantPlaya Del Rey222.56
Joint Water Pollution Control PlantCarson154.69
Point Loma Wastewater Treatment PlantSan Diego140.8
Orange County Sanitation District Plant 1Fountain Valley99.43
Ccsf- Southeast Water Pollution Control PlantSan Francisco72.75
Stockton RwcfStockton28.94
South Bay International WWTPSan Diego28.5
Riverside City, Water Quality ControlRiverside27.97
Encina Water Pollution Control FacilityCarlsbad23.63
Colton/san Bernardino Stp, RixColton20.79
La City , Pub Works DeptVan Nuys19.79
Regionwide Water Recycling System - Temescal Creek DischargeLake Elsinore19.76
Combined Wastewater Treatment PlantSacramento16.24
Valencia WwrpValencia15.64
Aliso Creek Ocean OutfallDana Point12.64
Monterey Regional WWTPMarina12.63
Oceanside Ocean OutfallOceanside10.99
ChinoChino10.94
Whittier Narrows Water Reclamation PlantSouth El Monte10.72
Escondido City OfEscondido10.14
City Of Tracy Waste Water Treatment PlantTracy9.33
Forest Shade Sewage Lift StationCrestline9.22
Groundwater Reliability Improvement Project - Advanced Water Treatment FacilityPico Rivera8.87
Western Riverside Co Reg WWTPCorona8.49
Victor Valley Wastewater Reclamation AuthorityVictorville8.44
Corona WWTP 1Corona7.32
Simi Vly Cnty SanitationSimi Valley7.12
Long Beach Water Reclamation PlantLong Beach6.98
Manteca WwqcfManteca6.91
Clear Creek WWTPAnderson6.72
Lompoc Wastewater PlantLompoc6.37
San Luis Obispo WWTPSan Luis Obispo5.6
Watsonville WWTFWatsonville5.28
Yuba City Wastewater Treatment FacilityYuba City5.16
Ventura Water Reclamation FacilityVentura4.94
Water Reclamation Plant No. 4Thermal4.75
Goleta Sd WWTPGoleta4.28
Redding Stillwater Wastewater Treatment PlantAnderson4.24
Camarillo Sanitary Dist Water Reclamation PlantCamarillo3.96
Saugus WwrpSaugus3.87
Woodland WPCFWoodland3.86
Davis Water Pollution Control PlantDavis3.8
Henry N. Wochholz Wastewater Treatment FacilityYucaipa3.8
Linda County WWTPMarysville3.74
Merced WWTFMerced3.61
El Centro WWTPEl Centro3.52
Beaumont WWTFBeaumont3.44
Sewerage Commission - Oroville RegionOroville3.13
Brentwood Wastewater Treatment PlantBrentwood2.88
Ironhouse Sd WWTPOakley2.81
Coachella Sd WWTPCoachella2.77
Michelson Treatment PlantIrvine2.6
Calera Creek WrpPacifica2.59
Brawley Wastewater Treatment PlantBrawley2.55
City Of Paso Robles Wastewater Treatment FacilityPaso Robles2.54
South San Luis Obispo Sd WWTPOceano2.25
Calexico Waste Water PlantCalexico2.02
Olivehurst WWTFOlivehurst1.99
Ojai Valley WWTPVentura1.98
El Dorado Hills WWTPEl Dorado Hills1.97
Mountain House WWTPMountain House1.42
Imperial WWTPImperial1.4
Carpinteria Sanitary DistrictCarpinteria1.39
City Of Arcata Wastewater Treatment FacilityArcata1.38
Fallbrook Pud WWTP No.1Fallbrook1.37
Auburnna City OfAuburn1.29
City Of Red Bluff Wastewater Reclamation PlantRed Bluff1.26
Anderson Wastewater Treatment PlantAnderson1.24
San Elijo WPCFCardiff1.2
Susanville Sd WWTPSusanville1.19
Healdsburg WWTFHealdsburg1.14
City Of Fortuna - Municipal Wastewater PlantFortuna1.13
Discovery Bay WWTPDiscovery Bay1.08
Willits Water Quality Control PlantWillits1.01
Pismo Beach WWTFPismo Beach1.01
Montecito Sd WWTPSanta Barbara0.98
Mckinleyville Csd - Wastewater Treatment PlantMckinleyville0.93
Shasta Lake WWTFShasta Lake0.86
Bear Valley Water DistrictBear Valley0.85
Live Oak City WWTPLive Oak0.8
California Mens ColonySan Luis Obispo0.76
Fort Bragg WWTFFort Bragg0.7
Calipatria WWTPCalipatria0.63
Corning Wastewater Treatment PlantCorning0.61
Willows WWTFWillows0.57
Colusa WWTPColusa0.55
Mt. Shasta WWTPMount Shasta0.54
Rio Vista WWTFRio Vista0.51
Quincy Community Services DistrictQuincy0.5
Scotts Valley WWTPScotts Valley0.49
Centinela SolarImperial0.47
Lake Of The Pines WWTPAuburn0.47
Copper Cove WwrfCopperopolis0.46
Nevada City Wastewater Treatment PlantNevada City0.41
Heber Pud WWTPHeber0.41
Holtville City WWTPHoltville0.37
Lake Wildwood WWTPPenn Valley0.37
Rio Dell POTWRio Dell0.35
Cottonwood WWTPCottonwood0.33
Northwest WWTFRio Vista0.33
Russian River POTWGuerneville0.31
Graton Csd WWTFGraton0.3
City Of Ferndale WWTPFerndale0.29
Calaveras Co Water DistrictSan Andreas0.27
Cayucos Sanitary District WRRFMorro Bay0.26
City Of Alturas Wastewater Treatment PlantAlturas0.26
Clovis Sewage Treatment And Water Reuse FacilityClovis0.25
Westmorland WWTPWestmorland0.2
Donner Summit WWTFSoda Springs0.19
Mariposa Pud WWTFMariposa0.18
Forestville Water District Wastewater Treatment, Recycling, & Disposal FacilityForestville0.15
Dunsmuir WWTPDunsmuir0.14
Mendocino City CsdMendocino0.09
Shelter Cove WWTFWhitethorn0.08
Summerland Sd WWTPSummerland0.08
Avila Beach WWTFAvila Beach0.07
Seeley County WWTPSeeley0.07
Loleta WWTFLoleta0.07
Niland Sd WWTPNiland0.06
Stallion Springs WWTFTehachapi0.06
Delleker WWTPPortola0.02
Anchor Bay WWTFAnchor Bay0.02
Harrah'S Northern California WWTPIone0.01
Hammonton Gold Village WWTPSmartsville0.01
Cascade Shores WWTPNevada City0.01
Town Of Samoa Wastewater Treatment FacilitySamoa0.01
Scotia WWTFScotia0.0031
Royal Palms Public RestroomSan Pedro0.0007
Paradise Cove WWTPTiburon0.000000013
American Canyon Waste Water Treatment FacilityAmerican Canyon—
Atwater Regional Wastewater Treatment FacilityAtwater—
Avalon WWTPAvalon—
Benicia WWTPBenicia—
Burbank WrpBurbank—
Burlingame WWTPBurlingame—
Carmel Area WWTPCarmel—
Central Contra Costa WWTFMartinez—
Chester WWTPChester—
City Of Cloverdale Wastewater Treatment PlantCloverdale—
City Of Lincoln WWTPLincoln—
City Of Livermore Sewage Treatment PlantLivermore—
City Of Morro Bay Water Reclamation FacilityMorro Bay—
City Of San Bernardino WRFSan Bernardino—
City Of St Helena Wastewater Treatment PlantSaint Helena—
City Of Ukiah Wastewater Treatment PlantUkiah—
Colton WWTFColton—
Contra Costa Co San Dist 7aAntioch—
Covelo WWTPCovelo—
Crescent City WWTFCrescent City—
Cutler-Orosi Joint Powers WastewaterCutler—
Dry Creek Regional Wastewater Treatment PlantRoseville—
Dublin-San Ramon WWTFPleasanton—
Dunaweal WWTPCalistoga—
East Bay Mud Main WWTPOakland—
Eureka Wastewater Treatment PlantEureka—
Hangtown Creek WWTPPlacerville—
Heritage Ranch CsdPaso Robles—
Hill Canyon WWTPCamarillo—
La City, La-Glendale Water ReclamationLos Angeles—
La Co., Sanitation DistPomona—
Lavwma Export And Storage FacilitiesPleasanton—
Lytton Wastewater Treatment Plant And Collection SystemWindsor—
Malibu Mesa WrpMalibu—
Mineral WWTPMineral—
Mt View Sanitary Dist WWTFMartinez—
Novato WWTPNovato—
Padre Dam WRFSantee—
Pinole WWTFPinole—
Pleasant Grove WWTPRoseville—
Portola WWTPPortola—
Raymond A. Boege Alvarado Wwtp, Old Alameda Creek Intermittent WwdUnion City—
Redway WWTFRedway—
Regional Wastewater FacilityLake Elsinore—
Rodeo Sanitary DistrictRodeo—
Sacramento County Wastewater Treatment PlantElk Grove—
San Mateo WWTFSan Mateo—
Santa Rosa Water - Laguna Treatment PlantSanta Rosa—
Sausalito-Marin City Sanitary DistrictSausalito—
Scwa: Sonoma Valley CsdtpSonoma—
Sewer Authority Mid-CoastsideHalf Moon Bay—
Sfia, Mel Leong Sanitary And Industrial Treatment PlantsSan Francisco—
Soscol WRFNapa—
South County Regional WastewatGilroy—
Southern Marin WWTPMill Valley—
Sunnyvale Water Pollution Control PlantSunnyvale—
Town Of Windsor Wastewater Treatment PlantWindsor—
Turlock RwqcfTurlock—
Vallejo Flood And Wastewater DistrictVallejo—
Valley Sanitary District WWTPIndio—
White Slough WPCFLodi—
Williams WWTPWilliams—
Yountville - Veterans WWTFYountville—

Wastewater treatment in California: 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: WWTP · POTW · MGD · NPDES permit · 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. “Wastewater treatment plants in California.” Updated October 26, 2026. https://klarifi.io/facilities/california

Need a custom cut of the data for a state, a county or a list of plants? Email info@klarifi.io.

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