Grinnell, City Of STP
Grinnell, IA · Poweshiek County · Publicly Owned Treatment Works
- Average flow
- —
- Design flow
- 5 MGD
- NPDES permit
- IA0031186
- Effective
- Permit expires
- November 2029
- Population served
- 9,624
- CWNS 2022
Grinnell, City Of STP is a publicly owned wastewater treatment works in Grinnell, Poweshiek County, Iowa, serving about 9,624 residents. Treatment on site includes clarifiers, carrousels / oxidation ditches. It discharges under NPDES permit IA0031186 (effective), which expires in November 2029, with 0 recorded violations in the last three years.
Treatment technology
Treatment structures identified at this facility. Exact unit counts are available in Klarifi.
Compliance snapshot (last 3 years)
- Total violations
- 0
- Effluent violations
- 0
Based on NPDES Discharge Monitoring Reports. Full violation history, parameters and discharge data available in the Klarifi platform.
Key contacts
1 verified contact for Grinnell, City Of STP, with validated emails and direct phone numbers.
Unlock 1 verified contact
Names, validated emails and direct phone numbers for decision-makers at Grinnell, City Of STP, plus the full compliance history and discharge data.
Nearby wastewater treatment plants in Iowa
Kellogg · 8 mi away
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Lynnville · 10 mi away
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Malcom · 11 mi away
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Searsboro · 11 mi away
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Gilman · 11 mi away
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Laurel · 14 mi away
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Newton · 16 mi away
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Brooklyn · 16 mi away
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Grinnell, 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 7, 2025.