Massachusetts / Events /

Combined sewer overflow: MASSACHUSETTS WATER RESOURCES AUTHORITY, Sep 27, 2026

Ended (as reported) · MASSACHUSETTS WATER RESOURCES AUTHORITY (MassDEP sewage notification portal)

Source: MASSACHUSETTS WATER RESOURCES AUTHORITY (MassDEP sewage notification portal) via MassDEP CSO API behind the portal (eeaonline.eea.state.ma.us/dep/CSOAPI/api/), record 6ab65d5c-a34d-4d05-9e6f-dc79368c6dcb, published Oct 8, 2026, 4:01 PM EDT, retrieved 2026-11-02 11:54 UTC · notice

1. The reported outfall

Outfall reported by MASSACHUSETTS WATER RESOURCES AUTHORITY (MA0103284 outfall MWR203): “JUST NORTH OF LOCKS AT CHARLSTOWN BRIDGE”. Location: 42.36895, -71.06090, from the state's or EPA's outfall layer.

2. Waters named in the notice

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

3. Modeled downstream reach

No modeled reach for this record in this build.

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

Sep 27, 2026, 8:34 AM EDT

Ended

Sep 27, 2026, 3:44 PM EDT

Precision

Known to the minute

Reported to the source

not given

Published

Oct 8, 2026, 4:01 PM 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 – Treated”

Volume

28.89 million gal (not stated whether estimated or measured)

Volume in the source's words

“28890000”

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

• Advisory in effect Charles River: Discharge in progress, Sep 27, 2026, 8:34 AM EDT to Sep 27, 2026, 3:44 PM EDT
• Advisory in effect Charles River: Within the authority's advice window after the discharge ended, Sep 27, 2026, 3:44 PM EDT to Sep 29, 2026, 3:44 PM EDT
• Caution Charles River: Within the site's caution window after the discharge ended (data/rules.json), Sep 29, 2026, 3:44 PM EDT to Sep 30, 2026, 3:44 PM EDT

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

6ab65d5c-a34d-4d05-9e6f-dc79368c6dcb

Original notice

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

Revision of

ma-massdep:364208db-effe-45dc-82c5-18ae369beb17

Revised by

no later revision

{
  "incidentId": "6ab65d5c-a34d-4d05-9e6f-dc79368c6dcb",
  "incidentNumber": "26017721",
  "incidentDate": "2026-09-27T00:00:00",
  "incidentTime": "08:34",
  "amPm": null,
  "reporterClass": "Verified Data Report",
  "eventType": "CSO – Treated",
  "permiteeClass": "CSO",
  "permiteeName": "MASSACHUSETTS WATER RESOURCES AUTHORITY",
  "permiteeId": "MA0103284",
  "outfallId": "MWR203",
  "municipality": "BOSTON",
  "reportingType": null,
  "location": "JUST NORTH OF LOCKS AT CHARLSTOWN BRIDGE",
  "latitude": null,
  "longitude": null,
  "waterBody": "CHARLES RIVER",
  "waterBodyDescription": null,
  "volumnOfEvent": "28890000",
  "rainfallData": "1.50",
  "hours": "7",
  "minutes": "10",
  "month": null,
  "year": null,
  "additionalInformation": null,
  "submittedDate": "2026-10-08T16:01:55.33",
  "parentIncidentId": null,
  "_report_class": "Verified Data Report",
  "_tz_assumed": "America/New_York (portal gives local clock time without zone)",
  "_ended_at_basis": "computed: started_at + verified duration 7 h 10 min (Verified Data Report)",
  "_coords": "MassDEP CSOs layer DEP_OUTFL_ MWR203 (locations are estimates)",
  "_water": {
    "via": "crosswalk on portal waterbody",
    "text": "CHARLES RIVER",
    "confidence": "high"
  },
  "_volume_note": "verified by permittee, reported to MassDEP (metered or modelled not stated)",
  "_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",
  "_link_basis": "same permittee and outfall as notice 26017605; start times 3 min apart"
}