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Wastewater treatment plants in Maine

92 facilities · 46 MGD combined flow

Klarifi tracks 92 publicly owned wastewater treatment plants in Maine with a combined average flow of 46 MGD, serving about 329,060 residents. 6 plants treat more than 1 MGD and 1 more than 10 MGD; 28 use lagoon systems and 25 have digesters or biogas infrastructure. The largest is East End Wastewater Treatment Facility in Portland at 13.14 MGD. 3 NPDES permits expire this year and 7 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.

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

NPDES permits and renewals in Maine

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 Maine →7 permits expiring in 2027 →9 permits expiring in 2028 →Find plants near you on the map →

Largest wastewater treatment plants in Maine

The 10 largest publicly owned wastewater treatment plants in Maine 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)
East End Wastewater Treatment FacilityPortland13.1419.8ME0102075Mar 202220
Bangor Wastewater Treatment FacilityBangor7.0918ME0100781Jul 203114
Westbrook Waste Water Treatmemt FacilityWestbrook3.054.54ME0100846Jul 202226
Brewer Wastewater Treatment FacilityBrewer1.475.19ME0100072Nov 20292
Sanford Wastewater Treatment FacilitySanford1.424.4ME0100617Jul 20234
Old Town Wastewater Treatment FacilityOld Town1.093.5ME0100471Sep 20292
Old Orchard Beach Wastewater Treatment FacilityOld Orchard Beach0.993.5ME0101524May 202012
York Wastewater Treatment FacilityYork0.993ME0101222Mar 203012
Gardiner WWTFGardiner0.974.5ME0101702Oct 20211
Bar Harbor WWTF Main FacilityBar Harbor0.912ME0101214Jan 20219

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

The 50 largest plants in Maine →EPA enforcement actions in Maine →Maine capital improvement plans →

Maine plants by treatment technology

Chlorine disinfection (48)Activated sludge and clarifiers (46)Lagoon systems (30)Anaerobic digesters and biogas (26)UV disinfection (7)Oxidation ditches (6)

All 92 plants in Maine

FacilityCityFlow (MGD)
East End Wastewater Treatment FacilityPortland13.14
Bangor Wastewater Treatment FacilityBangor7.09
Westbrook Waste Water Treatmemt FacilityWestbrook3.05
Brewer Wastewater Treatment FacilityBrewer1.47
Sanford Wastewater Treatment FacilitySanford1.42
Old Town Wastewater Treatment FacilityOld Town1.09
Old Orchard Beach Wastewater Treatment FacilityOld Orchard Beach0.99
York Wastewater Treatment FacilityYork0.99
Gardiner WWTFGardiner0.97
Bar Harbor WWTF Main FacilityBar Harbor0.91
Falmouth Waste Water Treatment FacilityFalmouth0.89
Canton Wastewater Treatment FacilityCanton0.77
Ellsworth Water Pollution Control FacilityEllsworth0.74
Pittsfield Wastewater Treatment FacilityPittsfield0.71
Anson Madison Wastewater Treatment FacilityMadison0.67
Camden Wastewater Treatment FacilityCamden0.67
Belfast Wastewater Treatment FacilityBelfast0.59
Yarmouth Wastewater Treatiment FacilityYarmouth0.55
Skowhegan Wastewater Treatment FacilitySkowhegan0.54
Calais Wastewater Treatment FacilityCalais0.52
Ogunquit Wastewater Treatment FacilityOgunquit0.49
Unity Ud WWTFUnity0.47
Livermore Falls WWTFLivermore Falls0.45
Lisbon Wastewater Treatment FacilityLisbon0.45
Madawaska WWTFMadawaska0.42
Jackman Wastewater Treatment FacilityJackman0.35
Norway Wastewater Treatment FacilityNorway0.33
Kennebunkport Wastewater Treatment FacilityKennebunkport0.32
Bucksport Wastewater Treatment FacilityBucksport0.31
Dover-Foxcroft Wastewater Treatment FacilityDover-Foxcroft0.31
Freeport Wastewater Treatment FacilityFreeport0.3
Ft Fairfield Wastewater Treatment FacilityFort Fairfield0.27
South Berwick Sd WWTFSouth Berwick0.25
Fort Kent WWTFFort Kent0.24
South Cape Elizabeth WWTFCape Elizabeth0.22
Newport Wastewater Treatement FacilityNewport0.22
Machias Wastewater Treatment FacilityMachias0.21
Northeast Harbor Wastewater Treatment FacilityNortheast Harbor0.2
Milo Wastewater Treatment FacilityMilo0.2
Wiscasset WWTFWiscasset0.17
Bingham WWTFBingham0.16
Warren Wastewater Treatment FacilityWarren0.14
Clinton WWTFClinton0.14
Richmond Wastewater Treatment FacilityRichmond0.14
Veazie WWTFVeazie0.13
Eastport WWTFEastport0.12
Ashland Wastwater Treatment FacilityAshland0.11
Howland WWTFHowland0.1
Limerick WWTFLimerick0.1
Hartland Wastewater Treatment FacilityHartland0.1
Bethel Wastewater Treatment FacilityBethel0.09
Peaks Island STPPortland0.08
Washburn Wastewater Treatment FacilityWashburn0.08
Sabattus Sanitary DistrictSabattus0.07
Passamaquoddy Wastewater Treatment FacilityPerry0.07
Seal Harbor WWTFSeal Harbor0.07
Searsport Wastewater Treatment FacilitySearsport0.06
Blue Hill, Wastewater Treatment FacilityBlue Hill0.05
Wastewater Treatment Facility Hulls CoveBar Harbor0.05
Frenchville Wastewater Treatment FacilityFrenchville0.05
Penobscot Housing Indian IslandOld Town0.04
Castine Wastewater Treatment FacilityCastine0.04
Lubec Wastewater Treatment FacilityLubec0.03
Danforth WWTFDanforth0.03
Moosehead Sanitary DistrictGreenville0.03
Milbridge WWTFMilbridge0.03
Eastport Quoddy WWTFEastport0.03
Winter Harbor WWTFWinter Harbor0.02
Somesville WWTFMount Desert0.02
Mattawamkeag WWTFMattawamkeag0.02
Passamaquoddy Water Treatment FacilityPerry0.02
Dark Harbor Wastewater Treatment FacilityIslesboro0.02
North Haven WWTFNorth Haven0.01
Thomaston Waste Water Treatment FacilityThomaston0.01
Vinalhaven WWTFVinalhaven0.01
Grand Isle WWTFGrand Isle0.01
Yarmouth Sea Meadows WWTFYarmouth0.0078
Biddeford Pool Wastewater Treatment FacBiddeford0.0075
Great Salt Bay Sanitary DistNobleboro0.0061
Bar Harbor Wastewater Treatment FacilityBar Harbor0.0035
Sorrento Wastewater Treatment FacilitySorrento0.0034
East Machias WWTFEast Machias0.0034
Patten Wastwater Treatment FacilityPatten0.003
Monson Utilities District Subsurface WwtsMonson0.0028
Bayville Village Wastewater Treatment FacilityBoothbay Harbor0.0027
Whitneyville WWTFWhitneyville0.0021
Eagle Lake Water & Sewer DistWallagrass0.0015
North Haven Pumping StationNorth Haven0.00072
Ellsworth WWTF SandfilterEllsworth0.00068
Dexter Utility DistrictDexter—
Rangeley Wastewater Treatment FacilityRangeley—
Subsurface Wastewater Trtmnt DischargeBridgton—

Wastewater treatment in Maine: 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 19, 2026.

Wastewater terms: WWTP · POTW · MGD · NPDES permit · Significant industrial user · Biosolids · 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 Maine.” Updated October 19, 2026. https://klarifi.io/facilities/maine

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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