Dayton STP
Dayton, WA · Columbia County · Publicly Owned Treatment Works
- Average flow
- 0.19 MGD
- Design flow
- —
- NPDES permit
- WA0020729
- Administratively continued
- Permit expires
- September 2016
- Population served
- 2,825
- CWNS 2022
Dayton STP is a publicly owned wastewater treatment works in Dayton, Columbia County, Washington treating an average of 0.19 million gallons per day, serving about 2,825 residents. Treatment on site includes clarifiers. It discharges under NPDES permit WA0020729 (administratively continued), which expires in September 2016, with 2 recorded violations in the last three years.
Treatment technology
Treatment structures identified at this facility. Exact unit counts are available in Klarifi.
Clarifiers
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Compliance snapshot (last 3 years)
- Total violations
- 2
- Effluent violations
- 2
Based on NPDES Discharge Monitoring Reports. Full violation history, parameters and discharge data available in the Klarifi platform.
Key contacts
Decision-makers at Dayton STP.
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Nearby wastewater treatment plants in Washington
Waitsburg · 9 mi away
—
Pomeroy · 21 mi away
0.09 MGD
Walla Walla · 25 mi away
—
Colton · 45 mi away
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Clarkston · 45 mi away
0.08 MGD
Clarkston · 46 mi away
0.71 MGD
Pullman · 48 mi away
2.13 MGD
Colfax · 50 mi away
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Dayton 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 May 29, 2025.