Massachusetts / Events /

Combined sewer overflow: LOWELL REGIONAL WASTEWATER UTILITY, Oct 11, 2026

Ended (as reported) · LOWELL REGIONAL WASTEWATER UTILITY (MassDEP sewage notification portal)

Source: LOWELL REGIONAL WASTEWATER UTILITY (MassDEP sewage notification portal) via MassDEP CSO API behind the portal (eeaonline.eea.state.ma.us/dep/CSOAPI/api/), record 41c6dc16-b968-44ba-940a-6d1b09380903, published Oct 12, 2026, 5:45 AM EDT, retrieved 2026-11-02 11:54 UTC · notice

1. The reported outfall

Outfall reported by LOWELL REGIONAL WASTEWATER UTILITY (MA0100633 outfall LOW030-2): “MERRIMACK STATION”. Location: 42.64530, -71.28892, from the state's or EPA's outfall layer.

2. Waters named in the notice

The notice names: “MERIMACK RIVER”. We place it on Merrimack River, MA. Matched by the name of the water in the source record.

3. Modeled downstream reach

Modeled downstream reach (estimate, not verified by sampling). Computed by DirtyWaterWatch from the river network and the nearest flow gauge; it is not an official advisory area.

• Unresolved: no end reported 0 to 2.7 km below the outfall

  0 to 2.7 km below the outfall · on Merrimack River

  If sewage entered the river at outfall 0302 at Oct 11 21:57, water from that point would typically reach here in about 2 hours (it could be as soon as about 1 hour) at the river flow measured at MERRIMACK RIVER BL CONCORD RIVER AT LOWELL, MA (2010 cfs) at 2026-11-02T11:30:00+00:00. This is a calculation from published USGS methods, not a measurement of bacteria. It does not mark where the river is or is not fit for contact.

• Unresolved: no end reported 2.7 to 3.2 km below the outfall

  2.7 to 3.2 km below the outfall · on Merrimack River

  If sewage entered the river at outfall 0302 at Oct 11 21:57, water from that point would typically reach here in about 2 hours (it could be as soon as about 1 hour) at the river flow measured at MERRIMACK RIVER BL CONCORD RIVER AT LOWELL, MA (2010 cfs) at 2026-11-02T11:30:00+00:00. This is a calculation from published USGS methods, not a measurement of bacteria. It does not mark where the river is or is not fit for contact.

• Unresolved: no end reported 3.2 to 7.8 km below the outfall

  3.2 to 7.8 km below the outfall · on Merrimack River

  If sewage entered the river at outfall 0302 at Oct 11 21:57, water from that point would typically reach here in about 6 hours (it could be as soon as about 3 hours) at the river flow measured at MERRIMACK RIVER BL CONCORD RIVER AT LOWELL, MA (2010 cfs) at 2026-11-02T11:30:00+00:00. This is a calculation from published USGS methods, not a measurement of bacteria. It does not mark where the river is or is not fit for contact.

• Unresolved: no end reported 7.8 to 9.7 km below the outfall

  7.8 to 9.7 km below the outfall · on Merrimack River

  If sewage entered the river at outfall 0302 at Oct 11 21:57, water from that point would typically reach here in about 7 hours (it could be as soon as about 4 hours) at the river flow measured at MERRIMACK RIVER BL CONCORD RIVER AT LOWELL, MA (2010 cfs) at 2026-11-02T11:30:00+00:00. This is a calculation from published USGS methods, not a measurement of bacteria. It does not mark where the river is or is not fit for contact.

• Unresolved: no end reported 9.7 to 13.1 km below the outfall

  9.7 to 13.1 km below the outfall · on Merrimack River

  If sewage entered the river at outfall 0302 at Oct 11 21:57, water from that point would typically reach here in about 10 hours (it could be as soon as about 6 hours) at the river flow measured at MERRIMACK RIVER BL CONCORD RIVER AT LOWELL, MA (2010 cfs) at 2026-11-02T11:30:00+00:00. This is a calculation from published USGS methods, not a measurement of bacteria. It does not mark where the river is or is not fit for contact.

• Unresolved: no end reported 13.1 to 16.1 km below the outfall

  13.1 to 16.1 km below the outfall · on Merrimack River

  If sewage entered the river at outfall 0302 at Oct 11 21:57, water from that point would typically reach here in about 12 hours (it could be as soon as about 7 hours) at the river flow measured at MERRIMACK RIVER BL CONCORD RIVER AT LOWELL, MA (2010 cfs) at 2026-11-02T11:30:00+00:00. This is a calculation from published USGS methods, not a measurement of bacteria. It does not mark where the river is or is not fit for contact.

  Model stops here: tidal below this point. Below this point water moves back and forth with the tide and wind, so we do not model where the discharge goes. See the official notice and local beach or shellfish advisories.

Open on the main map

When: three different times

The time of the event, the time the source reported, published or updated it, and the time we fetched it are kept apart. Times are shown in New England time; the record keeps the original offsets.

Started

Oct 11, 2026, 9:57 PM EDT

Ended

not reported

Precision

Known to the minute

Reported to the source

not given

Published

Oct 12, 2026, 5:45 AM EDT

Source last updated

not given

We fetched it

2026-11-02 11:54 UTC

What and how much

Type

Combined sewer overflow

Status in the record

Ended (as reported)

Material

“CSO – UnTreated”

Volume

not reported (not stated whether estimated or measured)

Volume in the source's words

none

Advice

“Avoid contact with these water bodies for 48 hours after the discharge or overflow ceases due to increased health risks from bacteria and other pollutants. See website for more information on whether specific resource areas, such as bathing beaches, are affected.”

Advice window

48 hours

Basis

314 CMR 16.04(10)(g)

What it does to the map, over time

• Caution Merrimack River: Discharge record with no status and no reported end, Oct 11, 2026, 9:57 PM EDT to Oct 26, 2026, 5:45 AM EDT
• Unresolved: no end reported Merrimack River: Unresolved: no end reported, Oct 26, 2026, 5:45 AM EDT to Nov 11, 2026, 4:45 AM EST
• No current report Merrimack River: Unresolved: no end reported (off the map after 30 days), Nov 11, 2026, 4:45 AM EST to Jan 9, 2027, 8:57 PM EST

Source: intervals computed by DirtyWaterWatch (build/status.py) from this record and the rules on the methods page, as of 2026-11-02 11:56 UTC.

Source and revisions

Source

MassDEP CSO API behind the portal (eeaonline.eea.state.ma.us/dep/CSOAPI/api/)

Record id at the source

41c6dc16-b968-44ba-940a-6d1b09380903

Original notice

https://eeaonline.eea.state.ma.us/portal/dep/cso-data-portal/detail…

Revision of

none (first record)

Revised by

no later revision

{
  "incidentId": "41c6dc16-b968-44ba-940a-6d1b09380903",
  "incidentNumber": "26017736",
  "incidentDate": "2026-10-11T00:00:00",
  "incidentTime": "21:57",
  "amPm": null,
  "reporterClass": "Public Notification Report",
  "eventType": "CSO – UnTreated",
  "permiteeClass": "CSO",
  "permiteeName": "LOWELL REGIONAL WASTEWATER UTILITY",
  "permiteeId": "MA0100633",
  "outfallId": "LOW030-2",
  "municipality": "LOWELL",
  "reportingType": "Initial-Ceased",
  "location": "MERRIMACK STATION",
  "latitude": null,
  "longitude": null,
  "waterBody": "MERIMACK RIVER",
  "waterBodyDescription": null,
  "volumnOfEvent": "",
  "rainfallData": "",
  "hours": "",
  "minutes": "",
  "month": null,
  "year": null,
  "additionalInformation": null,
  "submittedDate": "2026-10-12T05:45:46.903",
  "parentIncidentId": null,
  "_report_class": "Public Notification Report",
  "_tz_assumed": "America/New_York (portal gives local clock time without zone)",
  "_ended_note": "reported ceased; the portal gives no cessation time",
  "_coords": "MassDEP CSOs layer DEP_OUTFL_ LOW030-2 (locations are estimates)",
  "_water": {
    "via": "crosswalk on portal waterbody",
    "text": "MERIMACK RIVER",
    "confidence": "high"
  },
  "_advice_source": "required wording of 314 CMR 16.04(10)(g); the permittee's own advisory is only in an attachment the portal will not serve"
}