Merrimack WWTF
Merrimack, NH · Hillsborough County · Publicly Owned Treatment Works
- Average flow
- 1.37 MGD
- Design flow
- —
- NPDES permit
- NHR053094
- Administratively continued
- Permit expires
- February 2026
- Population served
- 15,850
- CWNS 2022
Merrimack WWTF is a publicly owned wastewater treatment works in Merrimack, Hillsborough County, New Hampshire treating an average of 1.37 million gallons per day, serving about 15,850 residents. Treatment on site includes clarifiers, biogas silos. It discharges under NPDES permit NHR053094 (administratively continued), which expires in February 2026, with 9 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
- 9
- Effluent violations
- 9
Based on NPDES Discharge Monitoring Reports. Full violation history, parameters and discharge data available in the Klarifi platform.
Key contacts
2 verified contacts for Merrimack WWTF, with validated emails and direct phone numbers.
Unlock 2 verified contacts
Names, validated emails and direct phone numbers for decision-makers at Merrimack WWTF, plus the full compliance history and discharge data.
Nearby wastewater treatment plants in New Hampshire
Nashua · 5 mi away
9.2 MGD
Milford · 8 mi away
0.78 MGD
Derry · 8 mi away
1.17 MGD
Hooksett · 18 mi away
0.68 MGD
Allenstown · 22 mi away
0.45 MGD
Concord · 26 mi away
3.2 MGD
Epping · 26 mi away
0.13 MGD
Exeter · 30 mi away
1.1 MGD
Merrimack WWTF: 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 September 11, 2026.