Colton STP
Colton, WA · Whitman County · Publicly Owned Treatment Works
- Average flow
- —
- Design flow
- 0.38 MGD
- NPDES permit
- WA0023175
- Administratively continued
- Permit expires
- May 2020
- Population served
- 452
- CWNS 2022
Colton STP is a publicly owned wastewater treatment works in Colton, Whitman County, Washington, serving about 452 residents. Treatment on site includes aerated lagoons, uncovered lagoons. It discharges under NPDES permit WA0023175 (administratively continued), which expires in May 2020, with 69 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
- 69
- Effluent violations
- 69
Based on NPDES Discharge Monitoring Reports. Full violation history, parameters and discharge data available in the Klarifi platform.
Key contacts
Decision-makers at Colton STP.
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Nearby wastewater treatment plants in Washington
Pullman · 10 mi away
2.13 MGD
Clarkston · 11 mi away
0.71 MGD
Clarkston · 16 mi away
0.08 MGD
Palouse · 23 mi away
0.04 MGD
Pomeroy · 24 mi away
0.09 MGD
Colfax · 25 mi away
—
Oakesdale · 38 mi away
—
Dayton · 45 mi away
0.19 MGD
Colton 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 November 8, 2025.