California / Reports /

Cyanobacteria advisory (harmful blue-green algae) reported, Aug 21, 2026

Advisory active · California State Water Resources Control Board (FHAB program)

Source: California State Water Resources Control Board (FHAB program) via Surface Water - Freshwater Harmful Algal Blooms, record 5313-3411, reported Aug 21, 2026, 12:00 AM PDT, retrieved 2026-11-06 03:07 UTC · Read the original notice

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1. Where the advisory applies

Issued by: California State Water Resources Control Board (FHAB program). Place named: “NF ~0.6mi below Basin Cr. (536TMR003)”. Location: 37.99435, -120.19254; location source: given in the source record.

2. Waters named in the notice

The notice names: “Tuolumne River”. DirtyWaterWatch links this report to Tuolumne River, CA. Match basis: the water named in the 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

Aug 21, 2026

Ended

not reported

Detail provided by the source

Times known to the day only

Reported to the source

Aug 21, 2026, 12:00 AM PDT

Published

not given

Source last updated

Aug 21, 2026, 12:00 AM PDT

Last retrieved by DirtyWaterWatch

2026-11-06 03:07 UTC

What was reported

Type

Cyanobacteria (harmful blue-green algae) can make water unfit for contact; the issuing authority decides when its advisory ends.

Status in the record

Advisory active

Advice from California State Water Resources Control Board (FHAB program)

“Algal mat alert sign advisory for cyanobacteria (harmful algal bloom), as recommended in the FHAB report”

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 a water not yet on the map: Official advisory in effect, Aug 20, 2026, 9:00 PM PDT to Sep 3, 2026, 9:00 PM PDT
• No current status shown a water not yet on the map: advisory not re-confirmed by its source recently, no map colour, Sep 3, 2026, 9:00 PM PDT to Nov 18, 2026, 8:00 PM PST (the end is scheduled: a new report can change it)

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

Source and versions

Source

Surface Water - Freshwater Harmful Algal Blooms

Source record number

5313-3411

Original notice

Read the original notice

Earlier version

None: this is the first record

Later versions

None

{
  "Bloom_Report_ID": 5313,
  "Report_Type": "Agency/Partner Reporting",
  "Bloom_Date_Created": "2026-08-21T08:41:25.000",
  "Water_Body_Name": "Tuolumne River",
  "Official_Water_Body_Name": null,
  "Landmark": "NF ~0.6mi below Basin Cr. (536TMR003)",
  "County": "Tuolumne",
  "Regional_Water_Board": "Region 5 - Central Valley",
  "Bloom_Latitude": 37.99435,
  "Bloom_Longitude": -120.19254,
  "Observation_Date": "2026-08-12",
  "Bloom_Texture": null,
  "Water_Body_Type": null,
  "Advisory_ID": 3411,
  "Advisory_Recommended": "Algal mat alert sign",
  "Advisory_Date": "2026-08-21",
  "AdvisoryStartDate": "2026-08-21",
  "AdvisoryEndDate": null,
  "AdvisoryDetail": "Alert-high concentration toxins",
  "Advisory_Date_of_Recommendation": "2026-08-21",
  "Case_ID": 1826,
  "Case_Status": "Open",
  "Case_End_Date": null,
  "Last_Field_Result_Sample_Date": null,
  "advisory_level": "Algal mat alert sign"
}