City Of St Helena Wastewater Treatment Plant
Saint Helena, CA · Napa County · Publicly Owned Treatment Works
- Average flow
- —
- Design flow
- 2.8 MGD
- NPDES permit
- CA0038016
- Expired
- Permit expires
- May 2026
- Population served
- 4,847
- CWNS 2022
City Of St Helena Wastewater Treatment Plant is a publicly owned wastewater treatment works in Saint Helena, Napa County, California, serving about 4,847 residents. Treatment on site includes aerated lagoons. It discharges under NPDES permit CA0038016 (expired), which expires in May 2026, with 198 recorded violations in the last three years.
Treatment technology
Treatment structures identified at this facility. Exact unit counts are available in Klarifi.
Aerated lagoons
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Compliance snapshot (last 3 years)
- Total violations
- 198
- Effluent violations
- 36
Based on NPDES Discharge Monitoring Reports. Full violation history, parameters and discharge data available in the Klarifi platform.
Key contacts
Decision-makers at City Of St Helena Wastewater Treatment Plant.
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Nearby wastewater treatment plants in California
Calistoga · 8 mi away
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Yountville · 9 mi away
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Sonoma · 17 mi away
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Windsor · 20 mi away
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Santa Rosa · 20 mi away
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Windsor · 20 mi away
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Napa · 21 mi away
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American Canyon · 23 mi away
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City Of St Helena Wastewater Treatment Plant: 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 July 29, 2026.