Derry Borough STP
Derry, PA · Westmoreland County · Publicly Owned Treatment Works
- Average flow
- 0.54 MGD
- Design flow
- 1.31 MGD
- NPDES permit
- PA0020788
- Expired
- Permit expires
- May 2026
- Population served
- 3,057
- CWNS 2022
Derry Borough STP is a publicly owned wastewater treatment works in Derry, Westmoreland County, Pennsylvania treating an average of 0.54 million gallons per day against a permitted design capacity of 1.31 MGD, serving about 3,057 residents. Treatment on site includes clarifiers. It discharges under NPDES permit PA0020788 (expired), which expires in May 2026, with 16 recorded violations in the last three years.
Treatment technology
Treatment structures identified at this facility. Exact unit counts are available in Klarifi.
Clarifiers
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Compliance snapshot (last 3 years)
- Total violations
- 16
- Effluent violations
- 16
Based on NPDES Discharge Monitoring Reports. Full violation history, parameters and discharge data available in the Klarifi platform.
Key contacts
1 verified contact for Derry Borough STP, with validated emails and direct phone numbers.
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Names, validated emails and direct phone numbers for decision-makers at Derry Borough STP, plus the full compliance history and discharge data.
Nearby wastewater treatment plants in Pennsylvania
Derry · 1 mi away
0.02 MGD
Latrobe · 5 mi away
3.1 MGD
Heilwood · 6 mi away
0.007 MGD
Blairsville · 7 mi away
0.36 MGD
Latrobe · 7 mi away
0.24 MGD
Ligonier · 7 mi away
0.34 MGD
Robinson · 9 mi away
0.04 MGD
Clarksburg · 9 mi away
0.0014 MGD
Derry Borough 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 September 11, 2026; facility record last updated November 28, 2025.