DirtyWaterWatch

New Hampshire / Dischargers /

City of Manchester DPW Environmental Protection Division (Manchester WWTF, 300 Winston St, and 15 CSOs)

CSO · New Hampshire · Manchester, Bedford, Goffstown, Londonderry

NPDES permit
NH0100447
Outfalls
15 with coordinates in the registry
Receiving waters
Merrimack River; Piscataquog River; Baker Brook (Tannery Brook); Rays Brook; Unnamed Brook
Tracked waters
Merrimack River, NH, Piscataquog River, NH
Events tracked
10 discharges · latest Oct 18, 2026, 8:23 AM EDT
Volume reported
16,426,070 gallons across the 2 discharges that give a volume (8 without one)

Source: discharger record from the project's research and EPA ECHO (dischargers.json); counts from the 10 event records below, as of 2026-11-02 11:56 UTC.

How it tells the public

(a) Web notice list https://www.manchesternh.gov/Departments/Sewer-and-Stormwater/CSO/CSO-Discharge-Notification. Posts are titled 'City Of Manchester CSO Notification - Activation' or '- No Activations for 12 Hours' and give no outfall, time or volume. (b) Email newsletter 'CSO Discharge Notification': page text says 'subscribe to the "CSO Discharge Notification" Newsletter by visiting our Newsletter page and filling out the form at the bottom' (https://www.manchesternh.gov/Residents/e-Services/Email-Notifications). (c) Flow Assessment Services ArcGIS map https://www.manchesternh.gov/csomap, an iframe of https://appservices.flowassessment.com/mapserver/cso_map.html?project=Manchester. Page text: 'identifies the six (6) combined sewer overflow (CSO)outfalls the city currently has active. Each outfall has a drop down menu that details the individual CSO activation time, termination time, and volume of discharge.' (d) 28 river signs at 14 outfalls, in English and Spanish.

Sign up for its notices

Source: the project's research on each operator's notification channel (research/<state>/dischargers.json), checked by fetching the operator's pages.

Outfalls

Source: water outlines from OpenBoatLaunch and OpenStreetMap contributors (ODbL); outfalls from EPA ECHO and the state outfall layers; modeled reaches computed by DirtyWaterWatch from USGS NLDI, NHDPlus and the nearest USGS gauge (Jobson 1996); basemap OpenFreeMap and OpenMapTiles.

15 outfalls in the registry
  • 011 Schiller Street · CSO · Merrimack River
  • 018 Turner/Ferry Streets · CSO · Merrimack River
  • 031 Stark Brook · CSO · Merrimack River
  • 039 Third Street · CSO · Piscataquog River
  • 043 Tannery Brook · CSO · Merrimack River
  • 044 Cemetery Brook · CSO · Merrimack River
  • 045 Granite Street · CSO · Merrimack River
  • 046 Bridge Street (East) · CSO · Merrimack River
  • 047 Pennacook Street · CSO · Merrimack River
  • 050 WWTP Manhole #1 · CSO · Merrimack River
  • 051 West Side Pumping Station Emergency Overflow · CSO · Merrimack River
  • 052 WWTP Manhole #2 · CSO · Merrimack River
  • 053 Walnut/North Streets and Canal/West Pennacook Streets · CSO · Merrimack River
  • 054 Ray Brook · CSO · Merrimack River
  • 055 Dunbar Street · CSO · Merrimack River

Source: EPA ECHO CSO outfall inventory matched to waters (data/outfalls-ne.json).

Event history

Events reported for City of Manchester DPW Environmental Protection Division (Manchester WWTF, 300 Winston St, and 15 CSOs), newest first
StartEnd Water OutfallTypeVolumeSourceLinks
not reported (reported Oct 18, 2026, 8:23 AM EDT) Oct 17, 2026, 8 PM EDT Merrimack River, NH, Piscataquog River, NH not stated Combined sewer overflowrevised not reported City of Manchester EPD (CSO Discharge Notification page) via nh-permittees, record manchester:Item14032, reported Oct 18, 2026, 8:23 AM EDT, retrieved 2026-11-02 11:55 UTC · notice Event: Combined sewer overflow, City of Manchester DPW Environmental Protection Division, not reported (reported Oct 18, 2026, 8:23 AM EDT) · Map
not reported (reported Oct 18, 2026, 8:23 AM EDT) Oct 17, 2026, 8:23 PM EDT Merrimack River, NH, Piscataquog River, NH not stated Combined sewer overflow not reported City of Manchester EPD (CSO Discharge Notification page) via nh-permittees, record manchester:Item14033, reported Oct 18, 2026, 8:23 AM EDT, retrieved 2026-11-02 11:55 UTC · notice Event: Combined sewer overflow, City of Manchester DPW Environmental Protection Division, not reported (reported Oct 18, 2026, 8:23 AM EDT) · Map
not reported (reported Oct 14, 2026, 12:08 AM EDT) Oct 17, 2026, 8 PM EDT Merrimack River, NH, Piscataquog River, NH not stated Combined sewer overflow not reported City of Manchester EPD (CSO Discharge Notification page) via nh-permittees, record manchester:Item14026, reported Oct 14, 2026, 12:08 AM EDT, retrieved 2026-11-02 11:55 UTC · notice Event: Combined sewer overflow, City of Manchester DPW Environmental Protection Division, not reported (reported Oct 14, 2026, 12:08 AM EDT) · Map
not reported (reported Oct 12, 2026, 3:04 PM EDT) Oct 17, 2026, 8 PM EDT Merrimack River, NH, Piscataquog River, NH not stated Combined sewer overflow not reported City of Manchester EPD (CSO Discharge Notification page) via nh-permittees, record manchester:Item14024, reported Oct 12, 2026, 3:04 PM EDT, retrieved 2026-11-02 11:55 UTC · notice Event: Combined sewer overflow, City of Manchester DPW Environmental Protection Division, not reported (reported Oct 12, 2026, 3:04 PM EDT) · Map
not reported (reported Oct 12, 2026, 1:53 PM EDT) Oct 12, 2026, 1:53 AM EDT Merrimack River, NH, Piscataquog River, NH not stated Combined sewer overflow not reported City of Manchester EPD (CSO Discharge Notification page) via nh-permittees, record manchester:Item14023, reported Oct 12, 2026, 1:53 PM EDT, retrieved 2026-11-02 11:55 UTC · notice Event: Combined sewer overflow, City of Manchester DPW Environmental Protection Division, not reported (reported Oct 12, 2026, 1:53 PM EDT) · Map
not reported (reported Oct 11, 2026, 9:21 PM EDT) Oct 12, 2026, 1 AM EDT Merrimack River, NH, Piscataquog River, NH not stated Combined sewer overflowrevised not reported City of Manchester EPD (CSO Discharge Notification page) via nh-permittees, record manchester:Item14022, reported Oct 11, 2026, 9:21 PM EDT, retrieved 2026-11-02 11:55 UTC · notice Event: Combined sewer overflow, City of Manchester DPW Environmental Protection Division, not reported (reported Oct 11, 2026, 9:21 PM EDT) · Map
not reported (reported Oct 7, 2026, 5:22 AM EDT) Oct 6, 2026, 5:22 PM EDT Merrimack River, NH, Piscataquog River, NH not stated Combined sewer overflow not reported City of Manchester EPD (CSO Discharge Notification page) via nh-permittees, record manchester:Item14013, reported Oct 7, 2026, 5:22 AM EDT, retrieved 2026-11-02 11:55 UTC · notice Event: Combined sewer overflow, City of Manchester DPW Environmental Protection Division, not reported (reported Oct 7, 2026, 5:22 AM EDT) · Map
not reported (reported Oct 3, 2026, 11:38 PM EDT) Oct 3, 2026, 11:38 AM EDT Merrimack River, NH, Piscataquog River, NH not stated Combined sewer overflow not reported City of Manchester EPD (CSO Discharge Notification page) via nh-permittees, record manchester:Item14011, reported Oct 3, 2026, 11:38 PM EDT, retrieved 2026-11-02 11:55 UTC · notice Event: Combined sewer overflow, City of Manchester DPW Environmental Protection Division, not reported (reported Oct 3, 2026, 11:38 PM EDT) · Map
not reported (reported Oct 3, 2026, 11:39 AM EDT) Oct 3, 2026, 11 AM EDT Merrimack River, NH, Piscataquog River, NH not stated Combined sewer overflowrevised not reported City of Manchester EPD (CSO Discharge Notification page) via nh-permittees, record manchester:Item14010, reported Oct 3, 2026, 11:39 AM EDT, retrieved 2026-11-02 11:55 UTC · notice Event: Combined sewer overflow, City of Manchester DPW Environmental Protection Division, not reported (reported Oct 3, 2026, 11:39 AM EDT) · Map
not reported (reported Sep 29, 2026, 11:39 AM EDT) Sep 28, 2026, 11:39 PM EDT Merrimack River, NH, Piscataquog River, NH not stated Combined sewer overflow not reported City of Manchester EPD (CSO Discharge Notification page) via nh-permittees, record manchester:Item14000, reported Sep 29, 2026, 11:39 AM EDT, retrieved 2026-11-02 11:55 UTC · notice Event: Combined sewer overflow, City of Manchester DPW Environmental Protection Division, not reported (reported Sep 29, 2026, 11:39 AM EDT) · Map
Apr 10, 2026, 1:00 AM EDT Apr 14, 2026, 12:00 PM EDT Piscataquog River, NH not stated Sanitary sewer overflow 1,070 gal EPA ECHO Sewer Overflow and Bypass Event report (reported to regulators) via ECHO NPDES Sewer Overflow and Bypass Event Dataset (eRule Phase 2, current versions), record NH0100447:59:1, reported Apr 16, 2026, 8:00 PM EDT, retrieved 2026-11-02 11:54 UTC · notice record below · Map
Full record (older than 180 days, so no page of its own)

This record in the archive list
Jul 15, 2023 Jul 15, 2023 Merrimack River, NH not stated Sanitary sewer overflow not reported EPA ECHO Sewer Overflow and Bypass Event report (reported to regulators) via ECHO NPDES Sewer Overflow and Bypass Event Dataset (eRule Phase 2, current versions), record NH0100447:26:1, reported Jul 25, 2023, 8:00 PM EDT, retrieved 2026-11-02 11:54 UTC · notice record below · Map
Full record (older than 180 days, so no page of its own)

This record in the archive list
Feb 8, 2023, 11:00 AM EST Feb 15, 2023, 7:15 AM EST Merrimack River, NH 044 Cemetery Brook Combined sewer overflow 16.43 million gal EPA ECHO Sewer Overflow and Bypass Event report (reported to regulators) via ECHO NPDES Sewer Overflow and Bypass Event Dataset (eRule Phase 2, current versions), record NH0100447:19:1, reported Mar 5, 2023, 7:00 PM EST, retrieved 2026-11-02 11:54 UTC · notice record below · Map
Full record (older than 180 days, so no page of its own)

This record in the archive list

History

  • Discharge events, last 12 months8Dec 2025 to Nov 2026; partly covered or sparse source
  • Days with a discharge, last 12 months15Dec 2025 to Nov 2026; partly covered or sparse source
  • Hours under advisory, last 12 months376Dec 2025 to Nov 2026; on this discharger's reports; partly covered or sparse source
  • 2026 season under advisory25%May to October, partly covered; 197 h

Discharge events per month

10 events, Jan 2022 to Nov 2026.

  • Combined sewer overflow
  • Sanitary sewer overflow
  • Bypass, blended or other
  • No source
  • Partly covered or sparse source
Sparse sourceSparse source

No source covers 2022-01 to 2022-04. EPA ECHO sewer overflow records are sparse (only what permittees file with EPA). NH permittees publish on their own pages; each discharger's record begins on a different date.

Sources: EPA ECHO sewer overflow events; NH permittee notices (Nashua, Manchester, Portsmouth, Exeter). Covered 2022-05-03 to 2026-11-02.

Show table
Discharge events per month
MonthCombined sewer overflowSanitary sewer overflowBypass, blended or otherTotalCounted fromCoverage
Jan 20220000No source
Feb 20220000No source
Mar 20220000No source
Apr 20220000No source
May 20220000Partly covered or sparse source
Jun 20220000Partly covered or sparse source
Jul 20220000Partly covered or sparse source
Aug 20220000Partly covered or sparse source
Sep 20220000Partly covered or sparse source
Oct 20220000Partly covered or sparse source
Nov 20220000Partly covered or sparse source
Dec 20220000Partly covered or sparse source
Jan 20230000Partly covered or sparse source
Feb 20231001Source recordsPartly covered or sparse source
Mar 20230000Partly covered or sparse source
Apr 20230000Partly covered or sparse source
May 20230000Partly covered or sparse source
Jun 20230000Partly covered or sparse source
Jul 20230101Source recordsPartly covered or sparse source
Aug 20230000Partly covered or sparse source
Sep 20230000Partly covered or sparse source
Oct 20230000Partly covered or sparse source
Nov 20230000Partly covered or sparse source
Dec 20230000Partly covered or sparse source
Jan 20240000Partly covered or sparse source
Feb 20240000Partly covered or sparse source
Mar 20240000Partly covered or sparse source
Apr 20240000Partly covered or sparse source
May 20240000Partly covered or sparse source
Jun 20240000Partly covered or sparse source
Jul 20240000Partly covered or sparse source
Aug 20240000Partly covered or sparse source
Sep 20240000Partly covered or sparse source
Oct 20240000Partly covered or sparse source
Nov 20240000Partly covered or sparse source
Dec 20240000Partly covered or sparse source
Jan 20250000Partly covered or sparse source
Feb 20250000Partly covered or sparse source
Mar 20250000Partly covered or sparse source
Apr 20250000Partly covered or sparse source
May 20250000Partly covered or sparse source
Jun 20250000Partly covered or sparse source
Jul 20250000Partly covered or sparse source
Aug 20250000Partly covered or sparse source
Sep 20250000Partly covered or sparse source
Oct 20250000Partly covered or sparse source
Nov 20250000Partly covered or sparse source
Dec 20250000Partly covered or sparse source
Jan 20260000Partly covered or sparse source
Feb 20260000Partly covered or sparse source
Mar 20260000Partly covered or sparse source
Apr 20260101Source recordsPartly covered or sparse source
May 20260000Partly covered or sparse source
Jun 20260000Partly covered or sparse source
Jul 20260000Partly covered or sparse source
Aug 20260000Partly covered or sparse source
Sep 20261001Source recordsPartly covered or sparse source
Oct 20266006Source records
Nov 20260000

Hours under advisory per month

Hours this discharger's reports put a water under an advisory, by the map's red rules.

  • Advisory in effect
  • No source
  • Partly covered or sparse source
Sparse sourceSparse source

No source covers 2022-01 to 2022-04. 5 discharge events have no reported end and no ongoing status; under the status rules they set caution, not an advisory, and add no hours here. Official beach and cyanobacteria advisories are counted on water pages only. EPA ECHO sewer overflow records are sparse (only what permittees file with EPA). NH permittees publish on their own pages; each discharger's record begins on a different date.

Sources: EPA ECHO sewer overflow events; NH permittee notices (Nashua, Manchester, Portsmouth, Exeter). Covered 2022-05-03 to 2026-11-02.

Show table
Hours under advisory per month
MonthHours under advisoryFrom discharge windowsHours in monthCoverage
Jan 202200744No source
Feb 202200672No source
Mar 202200744No source
Apr 202200720No source
May 202200744Partly covered or sparse source
Jun 202200720Partly covered or sparse source
Jul 202200744Partly covered or sparse source
Aug 202200744Partly covered or sparse source
Sep 202200720Partly covered or sparse source
Oct 202200744Partly covered or sparse source
Nov 202200720Partly covered or sparse source
Dec 202200744Partly covered or sparse source
Jan 202300744Partly covered or sparse source
Feb 2023236236672Partly covered or sparse source
Mar 202300744Partly covered or sparse source
Apr 202300720Partly covered or sparse source
May 202300744Partly covered or sparse source
Jun 202300720Partly covered or sparse source
Jul 20239696744Partly covered or sparse source
Aug 202300744Partly covered or sparse source
Sep 202300720Partly covered or sparse source
Oct 202300744Partly covered or sparse source
Nov 202300720Partly covered or sparse source
Dec 202300744Partly covered or sparse source
Jan 202400744Partly covered or sparse source
Feb 202400696Partly covered or sparse source
Mar 202400744Partly covered or sparse source
Apr 202400720Partly covered or sparse source
May 202400744Partly covered or sparse source
Jun 202400720Partly covered or sparse source
Jul 202400744Partly covered or sparse source
Aug 202400744Partly covered or sparse source
Sep 202400720Partly covered or sparse source
Oct 202400744Partly covered or sparse source
Nov 202400720Partly covered or sparse source
Dec 202400744Partly covered or sparse source
Jan 202500744Partly covered or sparse source
Feb 202500672Partly covered or sparse source
Mar 202500744Partly covered or sparse source
Apr 202500720Partly covered or sparse source
May 202500744Partly covered or sparse source
Jun 202500720Partly covered or sparse source
Jul 202500744Partly covered or sparse source
Aug 202500744Partly covered or sparse source
Sep 202500720Partly covered or sparse source
Oct 202500744Partly covered or sparse source
Nov 202500720Partly covered or sparse source
Dec 202500744Partly covered or sparse source
Jan 202600744Partly covered or sparse source
Feb 202600672Partly covered or sparse source
Mar 202600744Partly covered or sparse source
Apr 2026179179720Partly covered or sparse source
May 202600744Partly covered or sparse source
Jun 202600720Partly covered or sparse source
Jul 202600744Partly covered or sparse source
Aug 202600744Partly covered or sparse source
Sep 202600720Partly covered or sparse source
Oct 2026197197744
Nov 20260032

Days with a discharge per month

A day counts when any counted discharge was under way on it (start to reported end, local time); an event with no end counts its start day.

  • No source
  • Partly covered or sparse source
Sparse sourceSparse source

No source covers 2022-01 to 2022-04.

Sources: EPA ECHO sewer overflow events; NH permittee notices (Nashua, Manchester, Portsmouth, Exeter). Covered 2022-05-03 to 2026-11-02.

Show table
Days with a discharge per month
MonthDays with a dischargeCoverage
Jan 20220No source
Feb 20220No source
Mar 20220No source
Apr 20220No source
May 20220Partly covered or sparse source
Jun 20220Partly covered or sparse source
Jul 20220Partly covered or sparse source
Aug 20220Partly covered or sparse source
Sep 20220Partly covered or sparse source
Oct 20220Partly covered or sparse source
Nov 20220Partly covered or sparse source
Dec 20220Partly covered or sparse source
Jan 20230Partly covered or sparse source
Feb 20238Partly covered or sparse source
Mar 20230Partly covered or sparse source
Apr 20230Partly covered or sparse source
May 20230Partly covered or sparse source
Jun 20230Partly covered or sparse source
Jul 20231Partly covered or sparse source
Aug 20230Partly covered or sparse source
Sep 20230Partly covered or sparse source
Oct 20230Partly covered or sparse source
Nov 20230Partly covered or sparse source
Dec 20230Partly covered or sparse source
Jan 20240Partly covered or sparse source
Feb 20240Partly covered or sparse source
Mar 20240Partly covered or sparse source
Apr 20240Partly covered or sparse source
May 20240Partly covered or sparse source
Jun 20240Partly covered or sparse source
Jul 20240Partly covered or sparse source
Aug 20240Partly covered or sparse source
Sep 20240Partly covered or sparse source
Oct 20240Partly covered or sparse source
Nov 20240Partly covered or sparse source
Dec 20240Partly covered or sparse source
Jan 20250Partly covered or sparse source
Feb 20250Partly covered or sparse source
Mar 20250Partly covered or sparse source
Apr 20250Partly covered or sparse source
May 20250Partly covered or sparse source
Jun 20250Partly covered or sparse source
Jul 20250Partly covered or sparse source
Aug 20250Partly covered or sparse source
Sep 20250Partly covered or sparse source
Oct 20250Partly covered or sparse source
Nov 20250Partly covered or sparse source
Dec 20250Partly covered or sparse source
Jan 20260Partly covered or sparse source
Feb 20260Partly covered or sparse source
Mar 20260Partly covered or sparse source
Apr 20265Partly covered or sparse source
May 20260Partly covered or sparse source
Jun 20260Partly covered or sparse source
Jul 20260Partly covered or sparse source
Aug 20260Partly covered or sparse source
Sep 20261Partly covered or sparse source
Oct 20269
Nov 20260

Reported volume per year

Gallons, summed from the 2 events that gave a number (8 did not).

  • Partly covered or sparse source
Sparse sourceSparse source

8 of 10 events gave no volume as a number; only numbers are summed.

Sources: EPA ECHO sewer overflow events; NH permittee notices (Nashua, Manchester, Portsmouth, Exeter). Covered 2022-05-03 to 2026-11-02.

Show table
Reported volume per year
YearGallonsEvents with a numberEvents withoutCoverage
2022000Partly covered or sparse source
202316,425,00011Partly covered or sparse source
2024000Partly covered or sparse source
2025000Partly covered or sparse source
20261,07017Partly covered or sparse source

Hours under advisory per year

Hours under advisory each year; 2026 to date.

  • Advisory in effect
  • Partly covered or sparse source
Sparse sourceSparse source

5 discharge events have no reported end and no ongoing status; under the status rules they set caution, not an advisory, and add no hours here. Official beach and cyanobacteria advisories are counted on water pages only.

Sources: EPA ECHO sewer overflow events; NH permittee notices (Nashua, Manchester, Portsmouth, Exeter). Covered 2022-05-03 to 2026-11-02.

Show table
Hours under advisory per year
YearHours under advisoryShare of the yearCoverage
202200.0%Partly covered or sparse source
20233323.8%Partly covered or sparse source
202400.0%Partly covered or sparse source
202500.0%Partly covered or sparse source
20263765.1%Partly covered or sparse source

Share of the May to October season under advisory

Share of the hours from May 1 to October 31 with an advisory in effect.

  • Advisory in effect
  • Season partly covered

Seasons only partly covered by a source: 2026 (share is of the covered hours). 5 discharge events have no reported end and no ongoing status; under the status rules they set caution, not an advisory, and add no hours here. Official beach and cyanobacteria advisories are counted on water pages only.

Sources: EPA ECHO sewer overflow events; NH permittee notices (Nashua, Manchester, Portsmouth, Exeter). Covered 2022-05-03 to 2026-11-02.

Show table
Share of the May to October season under advisory
SeasonShare under advisoryHours under advisoryHours coveredSeason hoursPartly covered
202625.3%1977804,416yes

Discharge events by calendar month, all years

Every counted discharge event, by the calendar month it began.

Months are summed over every year a source covers; the table gives the number of years behind each month.

Sources: EPA ECHO sewer overflow events; NH permittee notices (Nashua, Manchester, Portsmouth, Exeter). Covered 2022-05-03 to 2026-11-02.

Show table
Discharge events by calendar month, all years
MonthEventsYears of records
Jan00
Feb10
Mar00
Apr10
May00
Jun00
Jul10
Aug00
Sep11
Oct61
Nov01
Dec00

Discharge events by outfall

The 1 outfalls with the most events of 1, all years.

EPA ECHO sewer overflow records are sparse (only what permittees file with EPA). NH permittees publish on their own pages; each discharger's record begins on a different date.

Sources: EPA ECHO sewer overflow events; NH permittee notices (Nashua, Manchester, Portsmouth, Exeter). Covered 2022-05-03 to 2026-11-02.

Show table
Discharge events by outfall
OutfallEvents
044 Cemetery Brook1
Outfall not stated9
How these charts are counted

Discharge events are counted once: where a source publishes both public notices and verified reports (MassDEP, Vermont DEC), a discharger's month with any verified report counts its verified reports only, and other months count notices. Revisions are folded into the record they revise, and EPA copies of a state report are not counted twice. Monthly and yearly totals (Maine DEP, EPA discharge monitoring reports, Portsmouth) are shown on their own and never added to the event counts. Hours under advisory follow the map's red rules. A muted band marks periods no source covers: a gap there is missing data, not a quiet month.

  • EPA ECHO sewer overflow events: 2022-05-03 to now (sparse)
  • NH permittee notices (Nashua, Manchester, Portsmouth, Exeter): 2026-09-29 to now