Mosier WWTP
1505 Rock Creek Rd, Mosier, OR 97040 · Wasco County · Publicly Owned Treatment Works
- Average flow
- 0.06 MGD
- Design flow
- 0.09 MGD
- NPDES permit
- OR0028045
- Administratively continued
- Permit expires
- January 2024
- Population served
- 470
- CWNS 2022
Mosier WWTP is a publicly owned wastewater treatment works in Mosier, Wasco County, Oregon treating an average of 0.06 million gallons per day against a permitted design capacity of 0.09 MGD, serving about 470 residents. It discharges under NPDES permit OR0028045 (administratively continued), which expires in January 2024, with 17 recorded violations in the last three years. EPA has recorded 1 formal enforcement action naming the plant, the latest in August 2021.
Treatment technology
Treatment structures and unit processes at Mosier WWTP.
Treatment structure data not yet analyzed for this facility.
Compliance snapshot (last 3 years)
- Total violations
- 17
- Effluent violations
- 6
Based on NPDES Discharge Monitoring Reports. Full violation history, parameters and discharge data available in the Klarifi platform.
EPA enforcement history
Federal civil enforcement cases, compliance inspections and informal actions recorded for Mosier WWTP in EPA's ICIS system.
- Formal actions
- 1
- 1 since FY2020
- Penalties assessed
- $52,500
- all cases
- Compliance actions
- $1M
- required by EPA orders
- EPA inspections
- 0
- none on record
Latest case · Aug 2021
UNION PACIFIC RAILROAD (UPRR)
Administrative order · CWA, NPDES Permit Violations · Final Order With Penalty · Penalty $52,500 · Compliance actions $1M
EPA's description of the case:
“EPA Region 10 Settles with Union Pacific Railroad Company, Mosier, OR for CWA Violations On August 27th, 2021 , Region 10 filed a consent agreement and final order resolving violations of the Clean…”
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Source: EPA ECHO, civil enforcement case 10-2021-0101.
Full case history with a free Klarifi account
Every action against Mosier WWTP with dates, milestones, violation types and EPA's complete case summaries, plus inspections and informal actions.
Key contacts
Decision-makers at Mosier WWTP.
No verified contacts on file yet
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Nearby wastewater treatment plants in Oregon
Hood River · 6 mi away
1.3 MGD
Hood River · 7 mi away
0.32 MGD
Mount Hood Parkdale · 15 mi away
0.06 MGD
Dufur · 21 mi away
0.05 MGD
Cascade Locks · 22 mi away
0.14 MGD
Biggs · 28 mi away
0.03 MGD
Government Camp · 32 mi away
0.1 MGD
Maupin · 38 mi away
0.06 MGD
Mosier WWTP: 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 October 1, 2025.
Wastewater terms: POTW · MGD · NPDES permit · Inflow and infiltration · Lift station · Sludge dewatering · all terms