How much wastewater does Monroe STP treat?

Monroe STP treats an average of 0.04 MGD and is permitted for a design flow of 0.18 MGD.

What treatment technology does Monroe STP use?

Klarifi has identified uncovered lagoons at the Monroe facility.

What is the NPDES permit for Monroe STP?

The facility discharges under NPDES permit OR0029203, currently effective, expiring April 2027.

Is Monroe STP in compliance?

Discharge monitoring reports show 14 violations at Monroe STP in the last three years, 2 of them effluent limit exceedances. The full history is available in Klarifi.

Who operates Monroe STP and how do I contact them?

Monroe STP is a publicly owned treatment works in Monroe, Oregon. Klarifi lists decision-maker contacts for this facility, available with a free trial.

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Monroe STP

Monroe, OR · Benton County · Publicly Owned Treatment Works

Average flow: 0.04 MGD

Design flow: 0.18 MGD

NPDES permit: OR0029203; Effective

Permit expires: April 2027

Population served: 640; CWNS 2022

Monroe STP is a publicly owned wastewater treatment works in Monroe, Benton County, Oregon treating an average of 0.04 million gallons per day against a permitted design capacity of 0.18 MGD, serving about 640 residents. Treatment on site includes uncovered lagoons. It discharges under NPDES permit OR0029203 (effective), which expires in April 2027, with 14 recorded violations in the last three years.

Treatment technology

Treatment structures identified at this facility. Exact unit counts are available in Klarifi.

Uncovered lagoons

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Compliance snapshot (last 3 years)

Total violations: 14

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 Monroe STP.

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Nearby wastewater treatment plants in Oregon

Alpine Community STP

Monroe · 3 mi away

0.0027 MGD

Harrisburg Lagoon Treatment Plant

Harrisburg · 6 mi away

—

Junction City STP

Junction City · 7 mi away

0.55 MGD

Halsey STP

Halsey · 9 mi away

0.04 MGD

Philomath WWTP

Corvallis · 15 mi away

0.43 MGD

Brownsville STP

Brownsville · 16 mi away

0.1 MGD

Coburg STP

Coburg · 16 mi away

0.15 MGD

Tangent STP

Tangent · 18 mi away

0.09 MGD

Monroe 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.

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