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Sanitary sewer overflow (SSO) reported — Los Angeles Cnty DPW, Sep 15, 2026

Ended (as reported) · California State Water Resources Control Board (CIWQS Sanitary Sewer System Database)

Source: California State Water Resources Control Board (CIWQS Sanitary Sewer System Database) via State Water Board CIWQS Sanitary Sewer System spill data: Cat1-2-3-Spills.txt (nightly flat file), record 908145, reported Sep 16, 2026, 6:20 AM PDT, retrieved 2026-11-05 15:08 UTC · Read the original notice

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1. Reported wastewater outlet

Operator named in the record: Los Angeles Cnty DPW (federal wastewater discharge permit, NPDES, 4SSO11365). Outlet: “2020-0502 ([house number removed] Potrero Grande Drive, Rosemead, CA) Unincorporated County Area”. Location: 34.04729, -118.09914; location source: given in the source record.

Outfall: a pipe or outlet where wastewater enters a water body.

2. Waters named in the notice

The notice names: “The drainage area is within the Alhambra Wash-Rio Hondo drainage system, within the Rio Hondo Watershed and ultimately the Los Angeles River Watershed.”. DirtyWaterWatch links this report to Alhambra Wash, CA, Rio Hondo, CA. Match basis: the water named in the report.

3. Estimated downstream stretch

No downstream estimate is available for this report.

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When it happened and when it was reported

Event and notice times use Eastern Time (EST or EDT). Retrieval times use Coordinated Universal Time (UTC).

Started

Sep 15, 2026, 3:22 PM PDT

Ended

Sep 15, 2026, 4:08 PM PDT

Detail provided by the source

Times known to the minute

Reported to the source

Sep 16, 2026, 6:20 AM PDT

Published

not given

Source last updated

Sep 29, 2026, 12:00 AM PDT

Last retrieved by DirtyWaterWatch

2026-11-05 15:08 UTC

What and how much

Type

Sanitary sewer overflow (SSO): sewage spills from a sewer meant to carry sewage separately from rainwater.

Status in the record

Ended (as reported)

Material

“untreated sewage”

Volume

500 gallons (estimated)

Volume as reported

“500 gallons spilled (estimated total leaving the sewer system); 400 gallons reached surface water; 100 gallons recovered”

Advice from California State Water Resources Control Board (CIWQS Sanitary Sewer System Database)

This report includes no advice. Check current local health notices.

Advice period

This report does not state a period. See the rule DirtyWaterWatch applies and its source.

Basis

not stated

Status history from this report

• Discharge or advisory reported Alhambra Wash: Discharge reported ongoing, Sep 15, 2026, 3:22 PM PDT to Sep 15, 2026, 4:08 PM PDT
• Caution Alhambra Wash: Within the caution period after the reported end, Sep 15, 2026, 4:08 PM PDT to Sep 18, 2026, 4:08 PM PDT
• Discharge or advisory reported Rio Hondo: Discharge reported ongoing, Sep 15, 2026, 3:22 PM PDT to Sep 15, 2026, 4:08 PM PDT
• Caution Rio Hondo: Within the caution period after the reported end, Sep 15, 2026, 4:08 PM PDT to Sep 18, 2026, 4:08 PM PDT

Source: DirtyWaterWatch calculations using this report and the published status rules. Updated 2026-11-06 09:03 UTC.

Source and versions

Source

State Water Board CIWQS Sanitary Sewer System spill data: Cat1-2-3-Spills.txt (nightly flat file)

Source record number

908145

Original notice

Read the original notice

Earlier version

None: this is the first record

Later versions

None

{
  "region": "4",
  "wdid": "4SSO11365",
  "enrollee_status": "Active",
  "system_name": "Unincorporated County Area CSMD South/County Sanitation District CS",
  "agency_name": "Los Angeles Cnty DPW",
  "spill_event_id": "908145",
  "version": "1.2",
  "spill_status": "Certified",
  "draft_submitted_on": "17-SEP-26",
  "first_certified_on": "29-SEP-26",
  "final_certified_on": "29-SEP-26",
  "spill_type": "Category 1 Spill",
  "location_name": "2020-0502 ([house number removed] Potrero Grande Drive, Rosemead, CA) Unincorporated County Area",
  "enrollee_notified_at": "09/15/2026 15:28",
  "crew_arrival_at": "09/15/2026 16:00",
  "start_at": "09/15/2026 15:22",
  "caloes_notified_at": "09/16/2026 06:20",
  "caloes_control_number": "26-4779",
  "technical_report_on": null,
  "lat": "34.04729",
  "lon": "-118.09914",
  "appearance_points": "Manhole",
  "volume_total_gal": "500",
  "reached_drainage_system": "Y",
  "volume_recovered_from_drainage_gal": "100",
  "volume_left_in_drainage_gal": "400",
  "volume_to_surface_water_gal": "400",
  "volume_recovered_gal": "100",
  "destinations": "Drainage Conveyance System that discharges to surface water; Paved Surface; Street/Curb and Gutter (2 3)",
  "destination_points_given": "Y",
  "end_at": "09/15/2026 16:08",
  "causes": "Debris-Rags",
  "failure_location": "Siphon",
  "storm_event": "N",
  "response_completed_at": "09/15/2026 17:40",
  "receiving_water": "The drainage area is within the Alhambra Wash-Rio Hondo drainage system, within the Rio Hondo Watershed and ultimately the Los Angeles River Watershed.",
  "receiving_water_type": "Other (specify below); River; Wash",
  "public_access_impact": "Other (specify below)",
  "closing_entity": "N/A",
  "days_closed_or_restricted": "0",
  "within_1000_ft_of_intake": "N",
  "samples_collected": "N",
  "spill_category": "1",
  "reached_water": true,
  "destination_points": [
    {
      "lat": 34.047,
      "lon": -118.099
    },
    {
      "lat": 34.048,
      "lon": -118.099
    }
  ]
}