Lagoon systems: wastewater treatment plants in Pennsylvania
90 plants · 11% of the state · 48 MGD reported by 87 plants
Klarifi identifies 90 publicly owned wastewater treatment plants with lagoon systems in Pennsylvania, 11% of the 790 plants in the state (48 MGD reported by 87 plants). The largest is Springettsbury Wastewater Treatment Plant in York at 9.09 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 Pennsylvania
| # | Facility | City | Avg flow (MGD) | NPDES permit | Expires | Violations (3y) |
|---|---|---|---|---|---|---|
| 1 | Springettsbury Wastewater Treatment Plant | York | 9.09 | PAL026808 | Dec 2030 | 4 |
| 2 | Clairton Mun Auth STP | Clairton | 4.78 | PAL026824 | Dec 2030 | 18 |
| 3 | Indiana Boro WWTP | Indiana | 4.67 | PA0026751 | Jun 2031 | 0 |
| 4 | Altoona Easterly STP | Altoona | 4.58 | PA0027014 | Sep 2026 | 4 |
| 5 | Ingleside STP | Johnstown | 2.64 | PA0026778 | Apr 2026 | 2 |
| 6 | Clearfield Mun Sew Sys STP | Clearfield | 1.84 | PA0026310 | Feb 2028 | 1 |
| 7 | Grove City Boro STP | Grove City | 1.56 | PA0020257 | Oct 2030 | 0 |
| 8 | Farrell Mun Sew | Farrell | 1.29 | PA0027227 | Jun 2017 | 20 |
| 9 | Amity Twp WWTP | Douglassville | 1.11 | PA0070351 | Apr 2028 | 16 |
| 10 | Wellsboro Muni Auth | Wellsboro | 1.04 | PAL021687 | Dec 2030 | 9 |
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 Pennsylvania
Lagoon systems in other states
Lagoon systems in Pennsylvania: 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 · Biosolids · Activated sludge · Oxidation ditch · all terms