Plymouth City Of STP
Plymouth, IA · Cerro Gordo County · Publicly Owned Treatment Works
- Average flow
- —
- Design flow
- 0.53 MGD
- NPDES permit
- IA0033383
- Effective
- Permit expires
- April 2030
- Population served
- 375
- CWNS 2022
Plymouth City Of STP is a publicly owned wastewater treatment works in Plymouth, Cerro Gordo County, Iowa, serving about 375 residents. Treatment on site includes uncovered lagoons. It discharges under NPDES permit IA0033383 (effective), which expires in April 2030, with 48 recorded violations in the last three years.
Treatment technology
Treatment structures identified at this facility. Exact unit counts are available in Klarifi.
Uncovered lagoons
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Compliance snapshot (last 3 years)
- Total violations
- 48
- Effluent violations
- 21
Based on NPDES Discharge Monitoring Reports. Full violation history, parameters and discharge data available in the Klarifi platform.
Key contacts
Decision-makers at Plymouth City Of STP.
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Mason City · 7 mi away
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Kensett · 9 mi away
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Nora Springs · 9 mi away
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Rudd · 13 mi away
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St. Ansgar · 14 mi away
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Plymouth City Of STP: frequently asked 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; facility record last updated March 28, 2025.