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World wastewater treatment plant observatory · data as reported by each inventory

Wastewater treatment plants in United States · Washington

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262 inventory records · EPA Clean Watersheds Needs Survey 2022

Data years: 2022. The inventory date does not establish current operation.

262 results

CompareNameNative sizeYear
QUINCY DOMESTIC STPQuincy0.72 MGD (million gallons per day)2022
Snoqualmie WWTPSnoqualmie0.72 MGD (million gallons per day)2022
Willapa Regional WWTPRaymond0.72 MGD (million gallons per day)2022
Woodland Wastewater Treatment PlantWoodland0.71 MGD (million gallons per day)2022
LA CENTER STPLa Center0.69 MGD (million gallons per day)2022
BLAINE STPBlaine0.68 MGD (million gallons per day)2022
MONTESANO WWPCPMontesano0.67 MGD (million gallons per day)2022
MORTON STPMorton0.62 MGD (million gallons per day)2022
SULTAN WWTPSultan0.612 MGD (million gallons per day)2022
CONNELL STPConnell0.61 MGD (million gallons per day)2022
EPHRATA STPEphrata0.604 MGD (million gallons per day)2022
MATTAWA WWTPMattawa0.6 MGD (million gallons per day)2022
COLFAX STPColfax0.6 MGD (million gallons per day)2022
GOLDENDALE POTWGoldendale0.6 MGD (million gallons per day)2022
OKANOGAN S/T FAC.Okanogan0.54 MGD (million gallons per day)2022
King County Vashon WWTPVashon0.52 MGD (million gallons per day)2022
OROVILLE POTWOroville0.5 MGD (million gallons per day)2022
BENTON CITY, S/T FAC.Benton City0.5 MGD (million gallons per day)2022
WINSLOW TREATMENTBainbridge Island0.5 MGD (million gallons per day)2022
ZILLAH TREATMENTZillah0.49 MGD (million gallons per day)2022
CARNATION TREATMENTCarnation0.48 MGD (million gallons per day)2022
ELMA STPElma0.48 MGD (million gallons per day)2022
KINGSTON STPKingston0.46 MGD (million gallons per day)2022
MANCHESTER STPManchester0.46 MGD (million gallons per day)2022
KITTITAS STPKittitas0.45 MGD (million gallons per day)2022
STEVENSON STPStevenson0.45 MGD (million gallons per day)2022
COWICHE REGIONAL POTWCowiche0.44 MGD (million gallons per day)2022
DEER PARK POTWDeer Park0.42 MGD (million gallons per day)2022
BREWSTER STPBrewster0.418 MGD (million gallons per day)2022
LYNDEN STPLynden0.41 MGD (million gallons per day)2022
Grand Mound WWTPRochester0.38 MGD (million gallons per day)2022
SNOQUALMIE PASS UD TREATMENTSnoqualmie Pass0.37 MGD (million gallons per day)2022
North Bay WWTPAllyn0.365 MGD (million gallons per day)2022
FORKS TREAT STPForks0.35 MGD (million gallons per day)2022
BINGEN POTWBingen0.35 MGD (million gallons per day)2022
Rock Island WWTPRock Island0.338 MGD (million gallons per day)2022
FRIDAY HARBOR STPFriday Harbor0.33 MGD (million gallons per day)2022
Belfair Wastewater & Water ReclaimBelfair0.32 MGD (million gallons per day)2022
WARDEN DOMESTIC STPWarden0.31 MGD (million gallons per day)2022
COUPEVILLE STPCoupeville0.3 MGD (million gallons per day)2022
GRAND COULEE WWTPGrand Coulee0.3 MGD (million gallons per day)2022
BRIDGEPORT WWTPBridgeport0.3 MGD (million gallons per day)2022
RIDGEFIELD WWTPRidgefield0.297 MGD (million gallons per day)2022
EVERSON STPEverson0.297 MGD (million gallons per day)2022
PALOUSE TREATMENT FACILITPalouse0.28 MGD (million gallons per day)2022
RITZVILLE STPRitzville0.273 MGD (million gallons per day)2022
POMEROY WWTPPomeroy0.27 MGD (million gallons per day)2022
NEWPORT WWTPNewport0.26 MGD (million gallons per day)2022
PACIFIC BEACH STPPacific Beach0.257 MGD (million gallons per day)2022
Wilbur Wastewater Treatment PlantWilbur0.255 MGD (million gallons per day)2022
LOON LAKE TREATMENTLoon Lake0.254 MGD (million gallons per day)2022
TOUTLE STPToutle0.25 MGD (million gallons per day)2022
MCCLEARY STPMccleary0.25 MGD (million gallons per day)2022
TONASKET POTWTonasket0.25 MGD (million gallons per day)2022
ROYAL CITY STPRoyal City0.25 MGD (million gallons per day)2022
LA CONNER TREATMENTLa Conner0.23 MGD (million gallons per day)2022
Tenino Wastewater FacilityTenino0.23 MGD (million gallons per day)2022
ROSLYN SewerRoslyn0.22 MGD (million gallons per day)2022
City of WESTPORT- WW Treatment/SewerWestport0.215 MGD (million gallons per day)2022
TEKOA STPTekoa0.2 MGD (million gallons per day)2022
Big Lake WWTPMount Vernon0.2 MGD (million gallons per day)2022
ODESSA STPOdessa0.197 MGD (million gallons per day)2022
COULEE DAM SewerCoulee Dam0.195 MGD (million gallons per day)2022
Mabton POTWMabton0.189 MGD (million gallons per day)2022
DIAMOND LAKE STPNewport0.187 MGD (million gallons per day)2022
HARTSTENE POINTE STPShelton0.186 MGD (million gallons per day)2022
NACHES STPNaches0.18 MGD (million gallons per day)2022
SOAP LAKE STPSoap Lake0.18 MGD (million gallons per day)2022
WILLIAMS LAKE SEWER DISTRICT NO 2Cheney0.168 MGD (million gallons per day)2022
DAVENPORT LAGOONDavenport0.16 MGD (million gallons per day)2022
REPUBLIC STPRepublic0.16 MGD (million gallons per day)2022
EASTSOUND W.D. STPEastsound0.16 MGD (million gallons per day)2022
GRANGER POTWGranger0.157 MGD (million gallons per day)2022
HARRINGTON WWTPHarrington0.155 MGD (million gallons per day)2022
LANGLEY STPLangley0.15 MGD (million gallons per day)2022
WAITSBURG STPWaitsburg0.15 MGD (million gallons per day)2022
CATHLAMET S/T FACILITYCathlamet0.15 MGD (million gallons per day)2022
TWISP POTWTwisp0.149 MGD (million gallons per day)2022
TOLEDO STPToledo0.148 MGD (million gallons per day)2022
SEKIU STPSekiu0.145 MGD (million gallons per day)2022
ASOTIN MUNICIPAL STPAsotin0.14 MGD (million gallons per day)2022
EATONVILLE STPEatonville0.13 MGD (million gallons per day)2022
PATEROS S/T FACILITYPateros0.13 MGD (million gallons per day)2022
ROCKFORD TOWN STPRockford0.13 MGD (million gallons per day)2022
ROSALIA STPRosalia0.13 MGD (million gallons per day)2022
VADER STPVader0.13 MGD (million gallons per day)2022
WHATCOM CNTY WATER DIST 13Maple Falls0.125 MGD (million gallons per day)2022
NORTH BONNEVILLE S/T FAC.North Bonneville0.125 MGD (million gallons per day)2022
KETTLE FALLS STPKettle Falls0.122 MGD (million gallons per day)2022
DALLESPORT TREATMENTGoldendale0.12 MGD (million gallons per day)2022
ALBION S/T FACILITYAlbion0.12 MGD (million gallons per day)2022
MOSSYROCK STPMossyrock0.12 MGD (million gallons per day)2022
WATERVILLE POTWWaterville0.118 MGD (million gallons per day)2022
ENDICOTT STPEndicott0.115 MGD (million gallons per day)2022
FAIRFIELD STPFairfield0.113 MGD (million gallons per day)2022
ENTIAT POTWEntiat0.11 MGD (million gallons per day)2022
Peshastin POTWPeshastin0.11 MGD (million gallons per day)2022
OAKESDALE S/T FACILITYOakesdale0.108 MGD (million gallons per day)2022
WAITTS LAKE SEWER SYSTEMValley0.101 MGD (million gallons per day)2022
CARBONADO S/T FAC.Carbonado0.1 MGD (million gallons per day)2022

Regulatory context

General reference. This is not an exhaustive review of applicable law.

United States: Clean Water Act / NPDES

NPDES regulates pollutant discharges from point sources to waters of the United States. The permit sets limits and monitoring conditions. A CWNS code identifies an inventory record, not an NPDES permit.

  • Permit identifier and permitting authority: EPA or an authorized state.
  • Outfall and receiving water; sewer connections follow a different control route.
  • Current permit conditions, limits and dated measurements; these are not included in CWNS.

References reviewed: 2026-11-06. Individual applicability: undetermined. This profile does not establish authorization or compliance.