Wilmington Wastewater Treatment Plant- 12th St & Hay Rd, Wilmington
Wilmington, DE · New Castle County · Publicly Owned Treatment Works
- Average flow
- 78.67 MGD
- Design flow
- —
- NPDES permit
- DEL020320
- Effective
- Permit expires
- December 2030
- Population served
- 530,079
- CWNS 2022
Wilmington Wastewater Treatment Plant- 12th St & Hay Rd, Wilmington is a publicly owned wastewater treatment works in Wilmington, New Castle County, Delaware treating an average of 78.67 million gallons per day, serving about 530,079 residents. Treatment on site includes clarifiers, uncovered lagoons. It discharges under NPDES permit DEL020320 (effective), which expires in December 2030, with 5 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
- 5
- Effluent violations
- 5
Based on NPDES Discharge Monitoring Reports. Full violation history, parameters and discharge data available in the Klarifi platform.
Key contacts
Decision-makers at Wilmington Wastewater Treatment Plant- 12th St & Hay Rd, Wilmington.
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Wilmington Wastewater Treatment Plant- 12th St & Hay Rd, Wilmington: 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 February 2, 2025.