Twisp WWTP
Twisp, WA · Okanogan County · Publicly Owned Treatment Works
- Average flow
- —
- Design flow
- 1.27 MGD
- NPDES permit
- WA0023370
- Administratively continued
- Permit expires
- February 2020
- Population served
- 1,059
- CWNS 2022
Twisp WWTP is a publicly owned wastewater treatment works in Twisp, Okanogan County, Washington, serving about 1,059 residents. Treatment on site includes clarifiers, carrousels / oxidation ditches. It discharges under NPDES permit WA0023370 (administratively continued), which expires in February 2020, with 0 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
- 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 Twisp WWTP.
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Nearby wastewater treatment plants in Washington
Winthrop · 8 mi away
0.06 MGD
Okanogan · 23 mi away
0.15 MGD
Brewster · 24 mi away
0.18 MGD
Omak · 26 mi away
0.53 MGD
Bridgeport · 30 mi away
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Chelan · 38 mi away
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Tonasket · 39 mi away
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Leavenworth · 47 mi away
—
Twisp 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 29, 2025.