Dayton STP
800 Stockton Rd, Dayton, WA 99328 · Columbia County · Publicly Owned Treatment Works
- Average flow
- 0.25 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 0.25 million gallons per day, serving about 2,825 residents. It discharges under NPDES permit WA0020729 (administratively continued), which expires in September 2016, with 2 recorded violations in the last three years.
Treatment technology
One treatment structure or unit process identified at Dayton STP.
Available with a free Klarifi account
See the full treatment train at Dayton STP: structures, unit processes and planned upgrades, with exact unit counts.
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
0.16 MGD
Pomeroy · 21 mi away
0.12 MGD
Walla Walla · 25 mi away
—
Walla Walla · 28 mi away
0.87 MGD
Colton · 45 mi away
0.08 MGD
Endicott · 45 mi away
0.08 MGD
Clarkston · 45 mi away
0.06 MGD
Clarkston · 46 mi away
0.69 MGD
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 October 26, 2026; facility record last updated May 29, 2025.
Wastewater terms: POTW · MGD · NPDES permit · Inflow and infiltration · Biological nutrient removal · Tertiary treatment · all terms