New Hampshire wastewater permits expiring in 2026
29 NPDES permits · 14 MGD combined average flow
29 publicly owned wastewater treatment plants in New Hampshire hold NPDES permits that expire during 2026, issued by US EPA Region 1 (with NHDES). The table lists each plant with its permit number, expiry month, average flow, treatment technology and three-year violation count, in order of expiry.
An NPDES permit runs for five years. To keep discharging, a plant must apply for renewal at least 180 days before the expiry date, and the renewed permit usually arrives with tighter effluent limits, new monitoring requirements or a compliance schedule. That is why the year a permit expires is the year a plant starts budgeting for upgrades: nutrient removal, disinfection, capacity or controls.
| Facility | City | Avg flow (MGD) | NPDES permit | Expires | Violations (3y) |
|---|---|---|---|---|---|
| Huckleberry Hill Wastewater Treatment Facility | Dover | 2.18 | NHG58A003 | Jan 2026 | 30 |
| Exeter Wastewater Treatment Facility | Exeter | 1.45 | NHG58A004 | Jan 2026 | 18 |
| Durham Wastewater Treatment Facility | Durham | 0.72 | NHG58A005 | Jan 2026 | 8 |
| Pease Wastewater Treatment Facility | Portsmouth | — | NHG58A007 | Jan 2026 | 65 |
| Leavitt E. Magrath Wastewater Treatment Facility | Hampton | 2.24 | NH0100625 | Feb 2026 | 29 |
| Merrimack WWTF | Merrimack | 1.29 | NHR053094 | Feb 2026 | 10 |
| Lebanon Wastewater Treatment Facility | Lebanon | 1.15 | NHR053176 | Feb 2026 | 2 |
| Keene Wastewater Treatment Facility | Keene | 1.87 | NH0100790 | Nov 2026 | 8 |
| Newmarket, Town Of - WPCF | Newmarket | 0.44 | NHG580013 | Nov 2026 | 17 |
| Sunapee, Town Of-WWTP | Sunapee | 0.3 | NHG580017 | Nov 2026 | 28 |
| Colebrook Wastewater Treatment Plant | Colebrook | 0.28 | NHG580315 | Nov 2026 | 33 |
| Town Of Bristol WWTF | Bristol | 0.2 | NHG580021 | Nov 2026 | 0 |
| Woodsville Wastewater Treatment Facility | Haverhill | 0.18 | NHG580978 | Nov 2026 | 26 |
| Epping Wasterwater Treatment Facility | Epping | 0.18 | NHG580012 | Nov 2026 | 121 |
| Lisbon Wastewater Treatment Facility | Lisbon | 0.18 | NHG580421 | Nov 2026 | 26 |
| Winchester Wastewater Treatment Plant | Winchester | 0.14 | NHG580404 | Nov 2026 | 2 |
| Henniker Wastewater Treatment Facility | Henniker | 0.13 | NHG580018 | Nov 2026 | 81 |
| Whitefield Wastewater Treatment Facility | Whitefield | 0.13 | NHG580002 | Nov 2026 | 22 |
| Hinsdale Wastewater Treatment Plant | Hinsdale | 0.12 | NHG580016 | Nov 2026 | 6 |
| Woodstock WWTF | Woodstock | 0.11 | NHG580020 | Nov 2026 | 32 |
| Newington Wastewater Treatment Plant | Portsmouth (newington) | 0.11 | NHG581141 | Nov 2026 | 83 |
| Groveton Wastewater Treatment Plant | Northumberland | 0.09 | NHG580226 | Nov 2026 | 15 |
| W Swanzey WWTF | Swanzey | 0.06 | NHG580015 | Nov 2026 | 182 |
| Town Of Hopkinton WWTP | Hopkington | 0.04 | NHG580579 | Nov 2026 | 25 |
| Northumberland Village Water Pollution Control Facility | Groveton | 0.04 | NHG581206 | Nov 2026 | 25 |
| Stratford Village System | North Stratford | 0.02 | NHG580536 | Nov 2026 | 8 |
| Cheshire County Maplewood Nursing Home | Westmoreland | 0.01 | NHG580391 | Nov 2026 | 14 |
| Lancaster Grange Wastewater Treatment Plant | Lancaster | 0.0034 | NHG581249 | Nov 2026 | 27 |
| Wallis Sands State Park | Rye | 0.0005 | NHG580014 | Nov 2026 | 51 |
New Hampshire permit renewals in 2026: 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.
Wastewater terms: NPDES permit · POTW · Biological nutrient removal · Tertiary treatment · Sludge dewatering · Significant industrial user · all terms
Cite this page
Journalists, researchers and educators are welcome to quote these figures. Please credit Klarifi as the source and link to this page.
Klarifi. “NPDES permits expiring in 2026: New Hampshire plants.” Updated October 26, 2026. https://klarifi.io/facilities/new-hampshire/permits-expiring/2026Need a custom cut of the data for a state, a county or a list of plants? Email info@klarifi.io.