Combined sewer overflow: BOSTON WATER & SEWER COMMISSION, May 19, 2026

Ended (as reported) · BOSTON WATER & SEWER COMMISSION (MassDEP sewage notification portal)

Source: BOSTON WATER & SEWER COMMISSION (MassDEP sewage notification portal) via MassDEP CSO API behind the portal (eeaonline.eea.state.ma.us/dep/CSOAPI/api/), record 9fd4f718-7abe-4b16-bd02-f05a41a83298, published May 20, 2026, 11:10 AM EDT, retrieved 2026-11-02 10:58 UTC · notice

Revised. Revised by ma-massdep:21b203bc-daa1-44b7-8df8-ba34511c6861. The newest revision is the one used for the map. see the revision

A report is not a test of the water. See how statuses are worked out.

1. The reported outfall

Outfall reported by BOSTON WATER & SEWER COMMISSION (MA0101192 outfall BOS010): “WEST OF BORDER ST ON EAST BANK BOS INNER HRBR”. Location: 42.37344, -71.04217, from the state's or EPA's outfall layer.

2. Waters named in the notice

The notice names: “BOSTON INNER HARBOR”. We place it on Mystic River, MA. Matched by the outfall's ID in the outfall registry, which places each outfall on a water.

outfall MA0101192 010 (geometry, 320 m)

3. Modeled downstream reach

No modeled reach for this record in this build.

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.

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: May 19, 2026, 6:40 PM EDT
Ended: May 20, 2026, 9:00 AM EDT
Precision: Known to the minute
Reported to the source: not given
Published: May 20, 2026, 11:10 AM EDT
Source last updated: not given
We fetched it: 2026-11-02 10:58 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.”
BOSTON WATER & SEWER COMMISSION (MassDEP sewage notification portal) · 314 CMR 16.04(10)(g)

Advice window: 48 hours
Basis: 314 CMR 16.04(10)(g)

Source and revisions

Source: MassDEP CSO API behind the portal (eeaonline.eea.state.ma.us/dep/CSOAPI/api/)
Record id at the source: 9fd4f718-7abe-4b16-bd02-f05a41a83298
Original notice: https://eeaonline.eea.state.ma.us/portal/dep/cso-data-portal/detail…
Revision of: none (first record)
Revised by: ma-massdep:21b203bc-daa1-44b7-8df8-ba34511c6861

Every field of the record

All fields of event ma-massdep:9fd4f718-7abe-4b16-bd02-f05a41a83298
`event_id`	ma-massdep:9fd4f718-7abe-4b16-bd02-f05a41a83298
`source_id`	ma-massdep
`source_record_id`	9fd4f718-7abe-4b16-bd02-f05a41a83298
`parent_event_id`	null
`event_type`	cso
`status`	ended
`discharger_id`	ma-bwsc
`discharger_name`	BOSTON WATER & SEWER COMMISSION
`npdes_permit`	MA0101192
`outfall_id`	BOS010
`outfall_name`	WEST OF BORDER ST ON EAST BANK BOS INNER HRBR
`waterbody_text`	BOSTON INNER HARBOR
`water_slugs`	["mystic-river-ma"]
`water_match`	outfall_registry
`lat`	42.373442
`lon`	-71.042169
`coord_source`	outfall_layer
`coord_precision_m`	null
`started_at`	2026-05-19T18:40:00-04:00
`ended_at`	2026-05-20T09:00:00-04:00
`time_precision`	minute
`reported_at`	null
`published_at`	2026-05-20T11:10:15-04:00
`source_updated_at`	null
`fetched_at`	2026-11-02T10:58:11Z
`material`	CSO – UnTreated
`volume_gal`	null
`volume_text`	null
`estimate_flag`	unknown
`authority`	BOSTON WATER & SEWER COMMISSION (MassDEP sewage notification portal)
`advice_text`	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_hours`	48
`advice_window_basis`	314 CMR 16.04(10)(g)
`source_url`	https://eeaonline.eea.state.ma.us/portal/dep/cso-data-portal/details/9fd4f718-7abe-4b16-bd02-f05a41a83298
`parse_error`	null
`fixture`	false
`superseded`	revised by ma-massdep:21b203bc-daa1-44b7-8df8-ba34511c6861
`reach`	MA0101192-010
`file`	events/ma-massdep~3A9fd4f718-7abe-4b16-bd02-f05a41a83298.json
`duplicate_of`	null
`placement_note`	outfall MA0101192 010 (geometry, 320 m)
`unplaced_reason`	null
`set_aside`	null
`reach_band`	null

The source's record (raw)

{
  "incidentId": "9fd4f718-7abe-4b16-bd02-f05a41a83298",
  "incidentNumber": "26016170",
  "incidentDate": "2026-05-19T00:00:00",
  "incidentTime": "18:40",
  "amPm": null,
  "reporterClass": "Public Notification Report",
  "eventType": "CSO – UnTreated",
  "permiteeClass": "CSO",
  "permiteeName": "BOSTON WATER & SEWER COMMISSION",
  "permiteeId": "MA0101192",
  "outfallId": "BOS010",
  "municipality": "BOSTON",
  "reportingType": "Initial-Ceased",
  "location": "WEST OF BORDER ST ON EAST BANK BOS INNER HRBR",
  "latitude": null,
  "longitude": null,
  "waterBody": "BOSTON INNER HARBOR",
  "waterBodyDescription": null,
  "volumnOfEvent": "",
  "rainfallData": "",
  "hours": "",
  "minutes": "",
  "month": null,
  "year": null,
  "additionalInformation": null,
  "submittedDate": "2026-05-20T11:10:15.207",
  "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_ BOS010 (locations are estimates)",
  "_water": {
    "echo_candidate": {
      "slug": "mystic-river-ma",
      "match": "geometry",
      "why_not": "geometry only, name differs"
    },
    "no_slug": [
      "BOSTON INNER HARBOR (no Boston Harbor slug)",
      "BOSTON INNER HARBOR (no Boston Harbor slug)"
    ]
  },
  "_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",
  "_ended_at_basis": "from Verified Data Report 26016287: its start + verified duration"
}

Personal fields (names, emails, phone numbers of staff) are removed from raw records before they are stored.