Winlock Wastewater Treatment Plant
1206 SW Mayer Ave, Winlock, WA 98596 · Lewis County · Publicly Owned Treatment Works
- Average flow
- 0.54 MGD
- Design flow
- —
- NPDES permit
- WA0021199
- Effective
- Permit expires
- February 2028
- Population served
- 1,534
- CWNS 2022
Winlock Wastewater Treatment Plant is a publicly owned wastewater treatment works in Winlock, Lewis County, Washington treating an average of 0.54 million gallons per day, serving about 1,534 residents. It discharges under NPDES permit WA0021199 (effective), which expires in February 2028, with 0 recorded violations in the last three years.
Treatment technology
One treatment structure or unit process identified at Winlock Wastewater Treatment Plant.
Available with a free Klarifi account
See the full treatment train at Winlock Wastewater Treatment Plant: structures, unit processes and planned upgrades, with exact unit counts.
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 Winlock Wastewater Treatment Plant.
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Winlock Wastewater Treatment Plant: 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 May 29, 2025.
Wastewater terms: POTW · MGD · NPDES permit · Inflow and infiltration · Lift station · Sludge dewatering · all terms