Monmouth STP
Monmouth, OR · Polk County · Publicly Owned Treatment Works
- Average flow
- 0.79 MGD
- Design flow
- 0.6 MGD
- NPDES permit
- OR0020613
- Effective
- Permit expires
- December 2030
- Population served
- 9,940
- CWNS 2022
Monmouth STP is a publicly owned wastewater treatment works in Monmouth, Polk County, Oregon treating an average of 0.79 million gallons per day against a permitted design capacity of 0.6 MGD, serving about 9,940 residents. Treatment on site includes aerated lagoons, uncovered lagoons. It discharges under NPDES permit OR0020613 (effective), which expires in December 2030, with 3 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
- 3
- Effluent violations
- 3
Based on NPDES Discharge Monitoring Reports. Full violation history, parameters and discharge data available in the Klarifi platform.
Key contacts
Decision-makers at Monmouth STP.
No verified contacts on file yet
Klarifi verifies plant and municipal decision-makers continuously. Start a free trial to browse contacts at nearby plants and flag this one for verification.
Nearby wastewater treatment plants in Oregon
Independence · 1 mi away
0.47 MGD
Rickreall · 5 mi away
1.42 MGD
Falls City · 10 mi away
0.009 MGD
Corvallis · 13 mi away
0.1 MGD
Salem · 13 mi away
24.62 MGD
Jefferson · 14 mi away
0.17 MGD
Albany · 16 mi away
4.59 MGD
Aumsville · 17 mi away
0.3 MGD
Monmouth 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 August 18, 2026.