Umatilla STP
Umatilla, OR · Umatilla County · Publicly Owned Treatment Works
- Average flow
- 0.72 MGD
- Design flow
- 0.8 MGD
- NPDES permit
- OR0022306
- Effective
- Permit expires
- December 2027
- Population served
- 6,574
- CWNS 2022
Umatilla STP is a publicly owned wastewater treatment works in Umatilla, Umatilla County, Oregon treating an average of 0.72 million gallons per day against a permitted design capacity of 0.8 MGD, serving about 6,574 residents. Treatment on site includes clarifiers, carrousels / oxidation ditches. It discharges under NPDES permit OR0022306 (effective), which expires in December 2027, with 0 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
- 0
- Effluent violations
- 0
Based on NPDES Discharge Monitoring Reports. Full violation history, parameters and discharge data available in the Klarifi platform.
Key contacts
Decision-makers at Umatilla STP.
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Nearby wastewater treatment plants in Oregon
Hermiston · 4 mi away
1.56 MGD
Stanfield · 11 mi away
0.15 MGD
Heppner · 40 mi away
0.07 MGD
Athena · 41 mi away
0.1 MGD
Arlington · 44 mi away
0.05 MGD
Elgin · 73 mi away
0.09 MGD
Biggs · 74 mi away
0.03 MGD
Long Creek · 84 mi away
0.03 MGD
Umatilla 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 18, 2025.