Williamstown STP
Sr 2039, Jefferson, PA 15344 · Washington County · Publicly Owned Treatment Works
- Average flow
- 0.04 MGD
- Design flow
- 0.3 MGD
- NPDES permit
- PA0096601
- Effective
- Permit expires
- January 2028
- Population served
- —
- CWNS 2022
Williamstown STP is a publicly owned wastewater treatment works in Jefferson, Washington County, Pennsylvania treating an average of 0.04 million gallons per day against a permitted design capacity of 0.3 MGD. It discharges under NPDES permit PA0096601 (effective), which expires in January 2028, with 7 recorded violations in the last three years.
Treatment technology
One treatment structure or unit process identified at Williamstown STP.
Available with a free Klarifi account
See the full treatment train at Williamstown STP: structures, unit processes and planned upgrades, with exact unit counts.
Compliance snapshot (last 3 years)
- Total violations
- 7
- Effluent violations
- 7
Based on NPDES Discharge Monitoring Reports. Full violation history, parameters and discharge data available in the Klarifi platform.
Key contacts
Decision-makers at Williamstown STP.
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Nearby wastewater treatment plants in Pennsylvania
Rices Landing · 2 mi away
0.04 MGD
Fredericktown · 3 mi away
0.13 MGD
Jefferson · 3 mi away
0.04 MGD
Carmichaels · 3 mi away
0.04 MGD
Labelle · 4 mi away
0.18 MGD
Marianna · 4 mi away
0.16 MGD
Richeyville · 6 mi away
0.12 MGD
Carmichaels · 7 mi away
0.53 MGD
Williamstown STP: 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 12, 2026; facility record last updated September 14, 2026.
Wastewater terms: POTW · MGD · NPDES permit · Inflow and infiltration · Filter press · FOG · all terms