Merrimack WWTF
36 Mast Rdd W Hwy, Merrimack, NH 03054 · Hillsborough County · Publicly Owned Treatment Works
- Average flow
- 1.29 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 1.29 million gallons per day, serving about 15,850 residents. It discharges under NPDES permit NHR053094 (administratively continued), which expires in February 2026, with 10 recorded violations in the last three years.
Treatment technology
2 treatment structures and unit processes identified at Merrimack WWTF.
Available with a free Klarifi account
See the full treatment train at Merrimack WWTF: structures, unit processes and planned upgrades, with exact unit counts.
Compliance snapshot (last 3 years)
- Total violations
- 10
- Effluent violations
- 10
Based on NPDES Discharge Monitoring Reports. Full violation history, parameters and discharge data available in the Klarifi platform.
EPA enforcement history
Federal civil enforcement cases, compliance inspections and informal actions recorded for Merrimack WWTF in EPA's ICIS system.
- Formal actions
- 0
- none on record
- EPA inspections
- 1
- latest Feb 2004
No formal federal enforcement case is on record for this plant.
Full case history with a free Klarifi account
Every action against Merrimack WWTF with dates, milestones, violation types and EPA's complete case summaries, plus inspections and informal actions.
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
9.77 MGD
Milford · 8 mi away
1.14 MGD
Derry · 8 mi away
1.46 MGD
Hooksett · 18 mi away
0.82 MGD
Allenstown · 22 mi away
0.53 MGD
Concord · 26 mi away
3.5 MGD
Epping · 26 mi away
0.18 MGD
Exeter · 30 mi away
1.45 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 October 26, 2026; facility record last updated September 11, 2026.
Wastewater terms: POTW · MGD · NPDES permit · Inflow and infiltration · Biosolids · Filter press · all terms