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Clean Water Act discharge permit · NPDES NH0100170

NASHUA WASTEWATER TREATMENT FACILITY, Nashua, NH: NPDES NH0100170 discharge permit, effluent exceedances, inspections, penalties

NASHUA WASTEWATER TREATMENT FACILITY, held by NASHUA CITY OF, holds NPDES permit NH0100170, which discharges to Merrimack River & Nashua River. EPA’s file records it issued May 31, 2000 and expiring July 31, 2005. The status and dates are as EPA’s permit file stood when Velarion loaded it (September 15, 2026); EPA’s free Detailed Facility Report on ECHO carries the permit’s current standing.

Identity

Facility as filedNASHUA WASTEWATER TREATMENT FACILITY
Permittee as filedNASHUA CITY OF
NPDES IDNH0100170
Permit statusAdministratively continued (past its expiration date and still in force until reissued)
Permit typeIndividual permit
Discharger classMajor discharger
Facility typePublicly owned treatment works
ProgramPublicly owned treatment works
IssuedMay 31, 2000
Expiration dateJuly 31, 2005
AddressNashua, NH 03060
Receiving waterMERRIMACK RIVER & NASHUA RIVER
Receiving water impaired303(D) Listed
SubwatershedUnkety Brook-Nashua River (HUC 010700040402)
Other EPA IDs (FRS)RCRA handler NHD500018569; ICIS-AIR source NH0000003301191104

Cited to the EPA ICIS-NPDES permit file (ECHO download); cross-program IDs from EPA’s FRS facility-registry crosswalk.

Effluent limits and exceedances

An effluent exceedance is a discharge monitoring report value over the permit’s numeric limit (EPA’s violation code E90). A violation of any kind also counts a report not filed. Each row is EPA’s own count for that pollutant.

Pollutant or measureLimitsViolations, any kindEffluent exceedancesLatest exceedanceLargest exceedance, as filed
Solids, total suspended15127113November 30, 2025471% over the limit
E. coli, thermotol, MF, MTEC1325090December 31, 202599,999% over the limit
BOD, 5-day, 20 deg. C1510573December 31, 202499,999% over the limit
pH62119September 30, 2023
LC50 Static 48Hr Acute Pimephales promelas12517June 30, 202550% over the limit
LC50 Static 48Hr Acute Ceriodaphnia dubia1156June 30, 202679% over the limit
Chlorine, total residual484September 30, 20081,404% over the limit
Solids, suspended percent removal132December 31, 201227% over the limit
BOD, 5-day, percent removal121June 30, 20069% over the limit
Rainfall events0760
Copper, total recoverable3110
Nitrogen, ammonia total [as N]190
Hardness, total [as CaCO3]190
Nickel, total recoverable190
Zinc, total recoverable190
Aluminum, total recoverable190
Cadmium, total recoverable190
Lead, total recoverable190
Flow, in conduit or thru treatment plant660
Chromium, total recoverable150
Alkalinity, total [as CaCO3]040
Bypass valve200
Bypass of treatment100

Cited to the EPA ICIS-NPDES limits and effluent violations files (ECHO download); up to 60 rows shown, most exceedances first.

Inspections, violations and enforcement

DateWhat EPA recordedAgency
August 3, 2026Wet-weather SSO, no discharge to waters of the U.S., that may endanger health or the environmentEP6
December 28, 2025Dry-weather SSO discharge to waters of the U.S. that may endanger health or the environmentEP6
November 25, 2025Dry-weather SSO, no discharge to waters of the U.S., that may endanger health or the environmentEP6
November 24, 2025Dry-weather SSO, no discharge to waters of the U.S., that may endanger health or the environmentEP6
November 17, 2025Dry-weather SSO, no discharge to waters of the U.S., that may endanger health or the environmentEP6
October 27, 2025Dry-weather SSO, no discharge to waters of the U.S., that may endanger health or the environmentEP6
September 10, 2025Dry-weather SSO, no discharge to waters of the U.S., that may endanger health or the environmentEP6
August 25, 2025PR: Failure to submit noncompliance report - CSO, SSO, or Bypass [40 CFR 122.41(l)(6) & (m)(3)(ii)]EP6
August 19, 2025Dry-weather SSO discharge to waters of the U.S. that may endanger health or the environmentEP6

Velarion’s copy of EPA’s ICIS-NPDES files does not include the inspections, formal enforcement actions and informal enforcement actions files, so this page shows none of them. EPA’s free Detailed Facility Report on ECHO lists this permit’s inspections, enforcement actions and penalties.

Cited to the EPA ICIS-NPDES violation, inspection and enforcement files (ECHO download); up to 50 rows of each shown, newest first.

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EPA publishes a free Detailed Facility Report for every permit on ECHO: its compliance status quarter by quarter, its inspections, and its enforcement actions and penalties. EPA also sends free notices of new inspections and enforcement actions through ECHO Notify; enter NPDES ID NH0100170 there.

Nearby on the register

Figures from EPA’s ICIS-NPDES download, loaded September 15, 2026.

What this page shows

This public-records page covers the Clean Water Act discharge permit NPDES NH0100170 for the Nashua Wastewater Treatment Facility in Nashua, NH, which is held by Nashua City of and discharges to the Merrimack River and Nashua River. The permit is administratively continued and classed as a Major Discharger, with 21 pollutants under a numeric limit and 9 pollutants with an effluent exceedance.