Williams WWTP
501 N Colusa Cut Opf Road, Williams, CA 95987 · Colusa County · Publicly Owned Treatment Works
- Average flow
- —
- Design flow
- 0.5 MGD
- NPDES permit
- CAC433345
- Effective
- Permit expires
- September 2031
- Population served
- —
- CWNS 2022
Williams WWTP is a publicly owned wastewater treatment works in Williams, Colusa County, California. It discharges under NPDES permit CAC433345 (effective), which expires in September 2031, with 58 recorded violations in the last three years.
Treatment technology
2 treatment structures and unit processes identified at Williams WWTP.
Available with a free Klarifi account
See the full treatment train at Williams WWTP: structures, unit processes and planned upgrades, with exact unit counts.
Compliance snapshot (last 3 years)
- Total violations
- 58
- Effluent violations
- 27
Based on NPDES Discharge Monitoring Reports. Full violation history, parameters and discharge data available in the Klarifi platform.
Key contacts
Decision-makers at Williams WWTP.
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Nearby wastewater treatment plants in California
Colusa · 7 mi away
0.55 MGD
Willows · 23 mi away
0.57 MGD
Live Oak · 26 mi away
0.8 MGD
Yuba City · 29 mi away
5.16 MGD
Marysville · 31 mi away
3.74 MGD
Olivehurst · 33 mi away
1.99 MGD
Oroville · 38 mi away
3.13 MGD
Woodland · 42 mi away
3.86 MGD
Williams 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 July 29, 2026.
Wastewater terms: POTW · MGD · NPDES permit · Inflow and infiltration · Oxidation ditch · Anaerobic digester · all terms