Twisp WWTP
1240B Cottonwood St, Twisp, WA 98856 · Okanogan County · Publicly Owned Treatment Works
- Average flow
- 0.07 MGD
- 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 treating an average of 0.07 million gallons per day against a permitted design capacity of 1.27 MGD, serving about 1,059 residents. It discharges under NPDES permit WA0023370 (administratively continued), which expires in February 2020, with 0 recorded violations in the last three years.
Treatment technology
2 treatment structures and unit processes identified at Twisp WWTP.
Available with a free Klarifi account
See the full treatment train at Twisp WWTP: 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 Twisp WWTP.
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Nearby wastewater treatment plants in Washington
Winthrop · 8 mi away
0.05 MGD
Okanogan · 23 mi away
0.16 MGD
Brewster · 24 mi away
0.16 MGD
Omak · 26 mi away
0.54 MGD
Bridgeport · 30 mi away
0.15 MGD
Chelan · 38 mi away
0.75 MGD
Tonasket · 39 mi away
0.1 MGD
Leavenworth · 47 mi away
0.02 MGD
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 October 26, 2026; facility record last updated November 29, 2025.
Wastewater terms: POTW · MGD · NPDES permit · Inflow and infiltration · Anaerobic digester · Lift station · all terms