Prosser City WWTP
Prosser, WA · Benton County · Publicly Owned Treatment Works
- Average flow
- —
- Design flow
- —
- NPDES permit
- WAR303447
- Terminated
- Permit expires
- December 2020
- Population served
- 6,616
- CWNS 2022
Prosser City WWTP is a publicly owned wastewater treatment works in Prosser, Benton County, Washington, serving about 6,616 residents. Treatment on site includes clarifiers, aerated lagoons, uncovered lagoons, biogas silos. It discharges under NPDES permit WAR303447 (terminated), which expires in December 2020, with 9 recorded violations in the last three years.
Treatment technology
Treatment structures identified at this facility. Exact unit counts are available in Klarifi.
Clarifiers
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Aerated lagoons
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Uncovered lagoons
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Biogas silos
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Compliance snapshot (last 3 years)
- Total violations
- 9
- 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 Prosser City WWTP.
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Nearby wastewater treatment plants in Washington
Grandview · 7 mi away
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Mabton · 11 mi away
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Sunnyside · 13 mi away
1.17 MGD
Sunnyside · 14 mi away
1.31 MGD
Benton City · 14 mi away
0.22 MGD
Granger · 22 mi away
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Richland · 23 mi away
6.31 MGD
Zillah · 27 mi away
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Prosser City 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 September 11, 2026; facility record last updated November 20, 2025.