Plymouth City Of STP
19683 325th St., Plymouth, IA 50464 · Cerro Gordo County · Publicly Owned Treatment Works
- Average flow
- 0.12 MGD
- 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 treating an average of 0.12 million gallons per day against a permitted design capacity of 0.53 MGD, serving about 375 residents. It discharges under NPDES permit IA0033383 (effective), which expires in April 2030, with 46 recorded violations in the last three years.
Treatment technology
One treatment structure or unit process identified at Plymouth City Of STP.
Available with a free Klarifi account
See the full treatment train at Plymouth City Of STP: structures, unit processes and planned upgrades, with exact unit counts.
Compliance snapshot (last 3 years)
- Total violations
- 46
- Effluent violations
- 19
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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Nearby wastewater treatment plants in Iowa
Rock Falls · 4 mi away
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Manly · 4 mi away
0.27 MGD
Grafton · 7 mi away
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Mason City · 7 mi away
5.13 MGD
Kensett · 9 mi away
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Nora Springs · 9 mi away
0.13 MGD
Rudd · 13 mi away
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St. Ansgar · 14 mi away
0.1 MGD
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 October 26, 2026; facility record last updated March 28, 2025.
Wastewater terms: POTW · MGD · NPDES permit · Inflow and infiltration · Equalization tank · Centrate · all terms