Lagoon systems: wastewater treatment plants in Ohio
260 plants · 31% of the state · 285 MGD reported by 212 plants
Klarifi identifies 260 publicly owned wastewater treatment plants with lagoon systems in Ohio, 31% of the 837 plants in the state (285 MGD reported by 212 plants). The largest is Akron WRF in Akron at 44.82 MGD.
Lagoon systems treat wastewater in large earthen ponds over weeks of retention time, with or without mechanical aeration. They serve thousands of small towns because they are cheap to run, but they struggle with ammonia and nutrient limits, fill with sludge over decades and are the plants most often converted or upgraded when a permit is renewed.
The largest lagoons in Ohio
| # | Facility | City | Avg flow (MGD) | NPDES permit | Expires | Violations (3y) |
|---|---|---|---|---|---|---|
| 1 | Akron WRF | Akron | 44.82 | OH0023833 | Aug 2028 | 0 |
| 2 | City Of Toledo Division Of Water Reclaimation | Toledo | 39.6 | OH0027740 | Jan 2029 | 3 |
| 3 | Lima WWTP | Lima | 11.44 | OH0026069 | Jun 2028 | 35 |
| 4 | City Of Warren Water Pollution Control | Warren | 10.13 | OH0027987 | Nov 2028 | 68 |
| 5 | Massillon WWTP | Massillon | 8.87 | OH0020516 | May 2031 | 0 |
| 6 | Upper Mill Creek Water Reclamation Facil | West Chester | 8.34 | OH0072087 | Dec 2023 | 33 |
| 7 | Beavercreek WRRF | Dayton | 7.3 | OH0025381 | Nov 2030 | 47 |
| 8 | Mason WWTP No 2 | Mason | 5.56 | OH0020494 | May 2026 | 1 |
| 9 | Lower East Fork Regional WWTP | Milford | 5.43 | OH0049379 | Oct 2026 | 4 |
| 10 | Barberton WPCF | Barberton | 5.02 | OH0024007 | Oct 2026 | 9 |
| 11 | Alum Creek WWTP | Delaware | 4.87 | OH0121380 | Dec 2030 | 8 |
| 12 | Lancaster Water Pollution Control | Lancaster | 4.7 | OH0026026 | Nov 2028 | 19 |
| 13 | Marion WPC | Marion | 4.64 | OH0026352 | Apr 2030 | 14 |
| 14 | Wooster Renewable Energy | Wooster | 4.42 | OH0028185 | Nov 2029 | 24 |
| 15 | Marysville WRF | Marysville | 3.83 | OH0136271 | Jun 2028 | 7 |
| 16 | Upper Olentangy Water Reclamation Center | Delaware | 3.68 | OH0024911 | Mar 2028 | 2 |
| 17 | Middle East Fork Regional WWTP | Batavia | 3.63 | OH0049387 | Feb 2031 | 25 |
| 18 | Alliance Water Tr. Plant And Wastewater Tr. Plant | Alliance | 3.6 | OH0023868 | Jul 2027 | 0 |
| 19 | North Olmsted WWTP | North Olmsted | 3.57 | OH0026778 | Jul 2030 | 5 |
| 20 | Fairborn Water Reclamation Center | Huber Hts | 3.48 | OH0025062 | Nov 2026 | 0 |
| 21 | Niles WWTP | Niles | 3.43 | OH0026743 | Sep 2028 | 9 |
| 22 | Olentangy Environmental Control Center | Powell | 3.41 | OH0054399 | Jul 2028 | 49 |
| 23 | Bowling Green | Bowling Green | 3.38 | OH0024139 | Apr 2027 | 13 |
| 24 | Wapakoneta WWTP | Wapakoneta | 2.84 | OH0027952 | Nov 2029 | 249 |
| 25 | Trumbull Mosquito Creek WWTP | Warren | 2.69 | OH0043401 | Jan 2027 | 44 |
Contacts and project signals for every plant on this list
Klarifi adds verified decision-maker contacts, permit limits, discharge monitoring data and the capital projects planned in each city, filterable by technology, size and compliance record.
Other technologies in Ohio
Lagoon systems in other states
Lagoon systems 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.