How many wastewater treatment plants are there in Ohio?

Klarifi tracks 837 publicly owned wastewater treatment plants in Ohio with a combined average flow of 941 million gallons per day, serving about 7,614,414 residents. 148 of them treat more than 1 MGD and 16 more than 10 MGD.

What is the largest wastewater treatment plant in Ohio?

Southerly Wastewater Treatment Plant in Lockbourne is the largest plant in Ohio by average flow, treating about 82.1 MGD.

What treatment technologies are common in Ohio?

260 of Ohio's plants use lagoon systems and 114 have biogas or anaerobic digestion infrastructure, based on Klarifi's aerial imagery review.

How many NPDES permits in Ohio are up for renewal?

114 permits held by Ohio plants expire in 2026 and 186 in 2027. Renewals typically bring new limits and trigger upgrade projects.

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Wastewater Treatment Plants in Ohio

Name: Wastewater treatment plants in Ohio
Creator: Klarifi
License: https://klarifi.io/terms-of-service

837 facilities · 941 MGD combined flow

Klarifi tracks 837 publicly owned wastewater treatment plants in Ohio with a combined average flow of 941 MGD, serving about 7,614,414 residents. 148 plants treat more than 1 MGD and 16 more than 10 MGD; 260 use lagoon systems and 114 have digesters or biogas infrastructure. The largest is Southerly Wastewater Treatment Plant in Lockbourne at 82.1 MGD. 114 NPDES permits expire this year and 186 next year.

Every plant below links to a profile with average and design flow, treatment technology, the NPDES permit and its expiry, a three-year compliance snapshot and the capital projects planned in its city. Showing facilities 1–200 of 837 by average flow — browse the rest with the page links below.

800 plant locations in Ohio; dot size follows average flow.

NPDES permits and renewals in Ohio

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 Ohio →114 permits expiring in 2026 →186 permits expiring in 2027 →167 permits expiring in 2028 →Find plants near you on the map →

Largest wastewater treatment plants in Ohio

The 25 largest publicly owned wastewater treatment plants in Ohio by average flow, with NPDES permit, expiry, treatment technology and three-year violation count. Source: EPA ICIS-NPDES via Klarifi.
Facility	City	Avg flow (MGD)	Design (MGD)	NPDES permit	Expires	Technology	Violations (3y)
Southerly Wastewater Treatment Plant	Lockbourne	82.1	—	OHL024741	Dec 2030	Clarifiers, Biogas silos	7
Southerly Wastewater Treatment Center	Cleveland	78.11	—	OHL024651	Dec 2030	Clarifiers, Biogas balloons	3
Akron WRF	Akron	44.82	90	OH0023833	Aug 2028	Clarifiers, Uncovered lagoons	0
City Of Toledo Division Of Water Reclaimation	Toledo	39.6	—	OH0027740	Jan 2029	Clarifiers, Uncovered lagoons, Biogas silos, Biogas balloons	3
City Of Dayton Water Reclamation Facility (0857100983)	Dayton	38.22	72	OH0024881	Apr 2027	Clarifiers, Biogas silos, Biogas balloons	17
Metropolitan Sewer Dis Little Miami WWTP	Cincinnati	21.87	55	OH0025453	Jun 2030	Clarifiers, Biogas balloons	8
Waste Water Treatment Plant	Youngstown	20.84	35	OH0028223	Oct 2028	Biogas silos, Biogas balloons	231
City Of Canton	Canton	20.5	39	OH0024350	May 2028	—	1
Neorsd Westerly Wwt Complex	Cleveland	18.52	35	OH0024660	Jun 2030	Biogas balloons	0
City Of Springfield Wastewater Treatment	Springfield	12.27	25	OH0027481	Feb 2030	Clarifiers, Biogas silos	39
Middletown Wastewater Treatment Plant	Middletown	11.69	26	OH0026522	Dec 2026	Clarifiers, Biogas silos, Biogas balloons	82
Maumee River Wastewater Treatment Plant	Waterville	11.65	22.5	OH0034223	Dec 2027	Clarifiers, Biogas balloons	15
Lakewood WWTP	Lakewood	11.52	18	OH0026018	Jul 2026	Clarifiers, Biogas silos, Biogas balloons	5
Lima WWTP	Lima	11.44	18.5	OH0026069	Jun 2028	Aerated lagoons, Uncovered lagoons, Cooling towers	35
City Of Euclid, Wastewater Treatment Plant	Euclid	10.45	22	OH0031062	Aug 2029	—	14
City Of Warren Water Pollution Control	Warren	10.13	16	OH0027987	Nov 2028	Clarifiers, Uncovered lagoons	68
Gary L Kron Water Reclamation Facility	Mentor	9.35	20	OH0043559	Mar 2027	Clarifiers, Biogas silos	29
Massillon WWTP	Massillon	8.87	17	OH0020516	May 2031	Clarifiers, Aerated lagoons, Biogas silos	0
Upper Mill Creek Water Reclamation Facil	West Chester	8.34	16	OH0072087	Dec 2023	Clarifiers, Aerated lagoons, Carrousels / oxidation ditches, Biogas balloons	33
Rocky River Wastewater Treatment Plant	Rocky River	8.3	22.5	OH0030503	Jan 2028	Biogas silos, Biogas balloons	15
Muddy Creek WWTP	Cincinnati	7.73	15	OH0025470	Mar 2030	Clarifiers, Biogas balloons	18
Black River Wastewater Treatment Plant	Lorain	7.69	15	OH0026093	Nov 2027	Clarifiers, Biogas silos	6
Western Regional WRF	West Carrollton	7.67	20	OH0026638	Oct 2026	Clarifiers	2
Lesourdsville Water Reclamation Facility	Hamilton	7.64	15	OH0049417	Nov 2026	—	6
Sandusky WPC	Sandusky	7.47	15.7	OH0027332	Apr 2031	Clarifiers, Biogas silos, Biogas balloons	0

The 50 largest plants in Ohio →Ohio capital improvement plans →

Ohio plants by treatment technology

Activated sludge and clarifiers (303)Lagoon systems (260)Anaerobic digesters and biogas (115)Oxidation ditches (113)

All 837 plants in Ohio

Facility	City	Flow (MGD)
Southerly Wastewater Treatment Plant	Lockbourne	82.1
Southerly Wastewater Treatment Center	Cleveland	78.11
Akron WRF	Akron	44.82
City Of Toledo Division Of Water Reclaimation	Toledo	39.6
City Of Dayton Water Reclamation Facility (0857100983)	Dayton	38.22
Metropolitan Sewer Dis Little Miami WWTP	Cincinnati	21.87
Waste Water Treatment Plant	Youngstown	20.84
City Of Canton	Canton	20.5
Neorsd Westerly Wwt Complex	Cleveland	18.52
City Of Springfield Wastewater Treatment	Springfield	12.27
Middletown Wastewater Treatment Plant	Middletown	11.69
Maumee River Wastewater Treatment Plant	Waterville	11.65
Lakewood WWTP	Lakewood	11.52
Lima WWTP	Lima	11.44
City Of Euclid, Wastewater Treatment Plant	Euclid	10.45
City Of Warren Water Pollution Control	Warren	10.13
Gary L Kron Water Reclamation Facility	Mentor	9.35
Massillon WWTP	Massillon	8.87
Upper Mill Creek Water Reclamation Facil	West Chester	8.34
Rocky River Wastewater Treatment Plant	Rocky River	8.3
Muddy Creek WWTP	Cincinnati	7.73
Black River Wastewater Treatment Plant	Lorain	7.69
Western Regional WRF	West Carrollton	7.67
Lesourdsville Water Reclamation Facility	Hamilton	7.64
Sandusky WPC	Sandusky	7.47
Beavercreek WRRF	Dayton	7.3
Findlay WPCF	Findlay	7.22
North Regional Wastewater Treatment Plan (0857143037)	Dayton	7.07
Mansfield Wastewater Treatment Plant	Mansfield	6.67
Newark WWTP	Newark	6.66
City Of Zanesville Wastewater Treatment Plant	Zanesville	5.91
Medina County - Liverpool WWTP (sd #500)	Valley City	5.85
Eastern Regional Water Reclamation Facility	Kettering	5.68
Mason WWTP No 2	Mason	5.56
City Of Elyria Wastewater Pollution Control Plant	Elyria	5.49
Lower East Fork Regional WWTP	Milford	5.43
Lower Little Miami WWTP	Maineville	5.43
Hamilton Water Reclamation Facility	Hamilton	5.26
Sycamore Creek WWTP	Cincinnati	5.2
Barberton WPCF	Barberton	5.02
French Creek WWTP	North Ridgeville	4.98
Alum Creek WWTP	Delaware	4.87
Sugarcreek WRF	Spring Valley	4.84
Lancaster Water Pollution Control	Lancaster	4.7
Marion WPC	Marion	4.64
Willoughby-Eastlake Water Pollution Cont	Eastlake	4.47
Wooster Renewable Energy	Wooster	4.42
Fremont WPCF	Fremont	4.02
Fairfield WWTP	Fairfield	3.88
Marysville WRF	Marysville	3.83
Avon Lake WPCF	Avon Lake	3.71
Upper Olentangy Water Reclamation Center	Delaware	3.68
Middle East Fork Regional WWTP	Batavia	3.63
Alliance Water Tr. Plant And Wastewater Tr. Plant	Alliance	3.6
Oregon Wastewater Treatment Plant	Oregon	3.58
North Olmsted WWTP	North Olmsted	3.57
Fairborn Water Reclamation Center	Huber Hts	3.48
Troy WWTP	Troy	3.48
Niles WWTP	Niles	3.43
Sidney WWTP	Sidney	3.42
Olentangy Environmental Control Center	Powell	3.41
Bowling Green	Bowling Green	3.38
Polk Run WWTP	Loveland	3.35
Portsmouth Lawson Run WWTP	Portsmouth	3.25
Perrysburg WWTP	Perrysburg	2.99
Wapakoneta WWTP	Wapakoneta	2.84
Struthers WWTP	Struthers	2.8
Ashtabula WPCP	Ashtabula	2.72
City Of Solon Water Reclamation Facility	Solon	2.69
Trumbull Mosquito Creek WWTP	Warren	2.69
Meander WPCF	Mineral Ridge	2.64
Athens WWTP	Athens	2.61
Upper Tuscarawas WWTP No 36	Akron	2.59
Pickerington WWTP	Pickerington	2.54
Boardman WWTP	Youngstown	2.53
City Of Twinsburg WWTP	Twinsburg	2.52
Ashland WWTP	Ashland	2.48
Lebanon WWTP	Lebanon	2.46
Fostoria City Dump	Fostoria	2.42
Taylor Creek WWTP	Cleves	2.38
Wadsworth WWTP	Wadsworth	2.32
Kenton WWTP	Kenton	2.3
New Philadelphia WWTP	New Philadelphia	2.27
Piqua WWTP	Piqua	2.18
Chillicothe WWTP - Easterly	Chillicothe	2.12
Defiance Water Pollution Control Plant	Defiance	2.07
London WWTP	London	2.06
Painesville WPC Plt	Painesville	2.06
Xenia Ford Road Wastewater Treatment Plant	Xenia	2.05
Oxford WWTP	Oxford	2.04
Madison WWTP No 1	Madison	2.01
Kent Water Reclamation Facility	Kent	2
Girard WWTP	Girard	1.97
Tiffin WWTP	Tiffin	1.97
Wilmington WWTP	Wilmington	1.94
Mount Vernon Wastewater Treatment Plant	Mount Vernon	1.92
Streetsboro Hudson Regional WWTP	Streetsboro	1.92
East Liverpool WWTP	East Liverpool	1.91
Southwest Licking W & Sd Gale Rd Envir Ctrl Fac	Hebron	1.87
Washington Court House WWTP	Washington Court House	1.87
Fairfield Co Tussing Road WWTP	Lancaster	1.81
Eastern Ohio Regional WW Authority	Bellaire	1.74
City Of Salem - Wastewater Plant	Salem	1.71
Miamisburg Water Reclamation Facility	Miamisburg	1.66
City Of Cambridge Water Pollution Control Center	Cambridge	1.65
Bellefontaine WWTP	Bellefontaine	1.62
North Royalton WWTP A	North Royalton	1.62
Springboro WWTP	Springboro	1.58
Philip Q Maiorana WWTP	Lorain	1.58
Orrville WWTP	Orrville	1.55
Minster WWTP	Minster	1.52
O'Bannon Creek Regional WWTP	Loveland	1.5
Glady Run WWTP	Xenia	1.47
Bucyrus WWTP	Bucyrus	1.44
Van Wert WWTP	Van Wert	1.44
Urbana WPCF	Urbana	1.42
Archbold Village	Archbold	1.42
Shelby WWTP	Shelby	1.42
Galion WWTP	Galion	1.42
Conneaut WWTP	Conneaut	1.39
Ironton WWTP	Ironton	1.39
Canal Winchester WWTP	Canal Winchester	1.39
Norwalk WWTP	Norwalk	1.32
Clyde WWTP	Clyde	1.28
Nine Mile Creek WWTP	New Richmond	1.22
Jackson WWTP	Jackson	1.2
Amherst Wpcc	Amherst	1.19
Greenville WWTP	Greenville	1.19
Medina Co Sd #300 Hinckley WWTP	Hinckley	1.18
Bedford WWTP	Bedford	1.17
Celina WWTP	Celina	1.17
Circleville WWTP	Circleville	1.17
Franklin Hills WWTP	Kent	1.15
Port Clinton WWTP	Port Clinton	1.15
City Of Dover Wastewater Treatment Plant	Dover	1.14
South Point Village	South Point	1.14
St Marys City WWTP	Saint Marys	1.12
Englewood WWTP	Englewood	1.11
Bedford Hts City Of	Bedford Heights	1.11
Gallipolis WPCF	Gallipolis	1.11
Southwest Regional WWTP	Medway	1.09
Napoleon WWTP	Napoleon	1.08
Louisville WWTP	Louisville	1.07
Oberlin Water Environment Protection Facility	Oberlin	1.05
Ravenna WWTP & Sewer System	Ravenna	1.04
Indian Lake Regional WWTP	Russells Point	1.03
Wellston WWTP North	Wellston	1.03
Upper Sandusky WWTP	Upper Sandusky	1.02
Willard WPCP	Willard	1
City Of Coshocton WWTP	Coshocton	0.99
Twin City WWTP	Uhrichsville	0.99
Mcfarland Creek WWTP	Bainbridge	0.97
Chillicothe Correctional Institution	Chillicothe	0.97
Shawnee No 2 WWTP	Lima	0.96
Harrison WWTP	Harrison	0.96
Hillsboro WWTP	Hillsboro	0.94
Hubbard WPCF	Hubbard	0.93
Delphos WWTP	Delphos	0.92
West Jefferson WWTP	West Jefferson	0.89
Logan WWTP	Logan	0.86
West Carrollton WWTP	W Carrollton	0.85
City Of Bryan Wastewater Treatment Plant	Bryan	0.84
Leipsic WWTP	Leipsic	0.84
Wheelersburg WWTP Sd No 2	Wheelersburg	0.84
Ottawa WWTP	Ottawa	0.79
City Of Bellevue WWTP	Bellevue	0.78
Newton Falls WPC	Newton Falls	0.76
City Of Vermilion WPCF	Vermilion	0.76
Danbury Twp WWTP	Port Clinton	0.76
American-Bath WWTP	Lima	0.74
Aqua Ohio Water Co Inc - Blacklick WWTP	Columbus	0.72
Heath WWTP	Heath	0.71
Aurora Westerly WWTP	Aurora	0.7
Plain City WWTP	Plain City	0.7
Eaton WWTP	Eaton	0.69
Sunbury WWTP	Sunbury	0.68
Columbiana WWTP	Columbiana	0.66
Pataskala WWTP	Pataskala	0.66
Geneva WWTP	Geneva	0.64
Union Rome Twps Sub-Sd WWTP	Chesapeake	0.63
Grafton WWTP	Grafton	0.62
Campbell WWTP	Campbell	0.62
Strongsville Cwwtp & Sewers	Strongsville	0.61
Rittman WWTP	Rittman	0.61
Wauseon WWTP	Wauseon	0.61
Brookville WWTP	Brookville	0.6
Brookfield WWTP	Masury	0.6
Belpre WWTP	Belpre	0.59
Indian Creek WWTP	North Bend	0.59
Strongsville B WWTP	Strongsville	0.59
Huron Basin WWTP	Huron	0.59
American No 2 WWTP	Elida	0.58
Chagrin Falls Meadow Lane WWTP	Chagrin Falls	0.58
Nelsonville WWTP	Nelsonville	0.57
Aqua Ohio Water Co Inc - Huber Ridge WWTP	Westerville	0.56
Aurora Central WWTP	Aurora	0.56
Union WWTP	Union	0.56
Pickaway Correctional Institute	Orient	0.56
New Lexington WWTP	New Lexington	0.55
Lucasville WWTP	Lucasville	0.55

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Wastewater treatment in Ohio: 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.

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