Twin Lakes Sanitary District STP
Rockwell City, IA · Calhoun County · Publicly Owned Treatment Works
- Average flow
- —
- Design flow
- 0.09 MGD
- NPDES permit
- IA0070114
- Effective
- Permit expires
- June 2030
- Population served
- 1,434
- CWNS 2022
Twin Lakes Sanitary District STP is a publicly owned wastewater treatment works in Rockwell City, Calhoun County, Iowa, serving about 1,434 residents. Treatment on site includes uncovered lagoons. It discharges under NPDES permit IA0070114 (effective), which expires in June 2030, with 14 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
- 14
- Effluent violations
- 14
Based on NPDES Discharge Monitoring Reports. Full violation history, parameters and discharge data available in the Klarifi platform.
Key contacts
1 verified contact for Twin Lakes Sanitary District STP, with validated emails and direct phone numbers.
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Names, validated emails and direct phone numbers for decision-makers at Twin Lakes Sanitary District STP, plus the full compliance history and discharge data.
Nearby wastewater treatment plants in Iowa
Pomeroy · 6 mi away
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Manson · 6 mi away
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Palmer · 11 mi away
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Rinard · 12 mi away
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Fonda · 12 mi away
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Barnum · 14 mi away
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Lake City · 14 mi away
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Clare · 17 mi away
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Twin Lakes Sanitary District 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 16, 2025.