California / Reports /
Cyanobacteria advisory (harmful blue-green algae) reported, Jul 7, 2024
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 4543-2806, reported Jun 28, 2024, 12:00 AM PDT, retrieved 2026-11-06 03:07 UTC · Read the original notice
Current status from this report
Discharge or advisory reported on Lake Del Valle: Official advisory in effect. Current rule period ends Nov 12, 2026, 8:00 PM PST. This is not a water-quality test.
Why this status: Discharge or advisory reported: official advisory.
Why we use this rule: An official advisory is listed. We show it while the authority keeps it in place; an old or missing update does not mean the advisory was lifted.
A report is not a test of the water. See how we assign statuses.
Read the original notice · Report an error
1. Where the advisory applies
Issued by: California State Water Resources Control Board (FHAB program). Place named: “East Beach”. Location: 37.58431, -121.69951; location source: given in the source record.
2. Waters named in the notice
The notice names: “Lake Del Valle”. DirtyWaterWatch links this report to Lake Del Valle, CA. Match basis: the water named in the report.
Map sources: water outlines and launches from OpenBoatLaunch and OpenStreetMap contributors (Open Database License); wastewater outlets from EPA and state records; downstream estimates by DirtyWaterWatch using U.S. Geological Survey maps and flow data. Base map: OpenFreeMap and OpenMapTiles.
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
- Ended
- not reported
- Detail provided by the source
- Times known to the day only
- Reported to the source
- Published
- not given
- Source last updated
- Last retrieved by DirtyWaterWatch
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)
“Caution 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 Lake Del Valle: Official advisory in effect, Jul 6, 2024, 9:00 PM PDT to Nov 12, 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
- 4543-2806
- Original notice
- Read the original notice
- Earlier version
- None: this is the first record
- Later versions
- None
Record details
| Record identifier | ca-swrcb-fhab:4543-2806 |
|---|---|
| Source identifier | ca-swrcb-fhab |
| Source record number | 4543-2806 |
| Earlier version | Not provided |
| Type | Cyanobacteria advisory (harmful blue-green algae) |
| Status in the report | Advisory active |
| Sewer operator identifier | Not provided |
| Sewer operator | Not provided |
| Federal wastewater discharge permit (NPDES) | Not provided |
| Outlet number | Not provided |
| Outlet name | East Beach |
| Water named in the report | Lake Del Valle |
| Linked waters | lake-del-valle-ca |
| How this report was linked to the water | the water named in the report |
| Latitude | 37.584 |
| Longitude | -121.7 |
| Location source | given in the source record |
| Location accuracy, in metres | Not provided |
| Started | Jul 7, 2024 (2024-07-07) |
| Ended | Not provided |
| Detail provided by the source | to the day only |
| Reported to the source | Jun 28, 2024 (2024-06-28) |
| Published | Not provided |
| Source last updated | Oct 30, 2026 (2026-10-30) |
| Last retrieved by DirtyWaterWatch | Nov 5, 2026, 7:07 PM PST (2026-11-06T03:07:10Z) |
| Material | Not provided |
| Volume, in gallons | Not provided |
| Volume as reported | Not provided |
| How volume was determined | not stated whether estimated or measured |
| Authority | California State Water Resources Control Board (FHAB program) |
| Advice | Quoted in full above |
| Advice period, in hours | Not provided |
| Basis of the advice period | Not provided |
| Original notice | https://data.ca.gov/dataset/surface-water-freshwater-harmful-algal-blooms/resource/c6a36b91-ad38-4611-8750-87ee99e497dd |
Original source data
{
"Bloom_Report_ID": 4543,
"Report_Type": "Public Reporting",
"Bloom_Date_Created": "2024-06-28T09:51:14.000",
"Water_Body_Name": "Lake Del Valle",
"Official_Water_Body_Name": null,
"Landmark": "East Beach",
"County": "Alameda",
"Regional_Water_Board": "Region 2 - San Francisco Bay",
"Bloom_Latitude": 37.584306,
"Bloom_Longitude": -121.69951,
"Observation_Date": "2024-06-25",
"Bloom_Texture": null,
"Water_Body_Type": null,
"Advisory_ID": 2806,
"Advisory_Recommended": "Caution",
"Advisory_Date": "2026-10-30",
"AdvisoryStartDate": "2024-07-07",
"AdvisoryEndDate": null,
"AdvisoryDetail": "Lake-wide advisory; Updates from routine monitoring program-organization",
"Advisory_Date_of_Recommendation": "2026-10-30",
"Case_ID": 1215,
"Case_Status": "Ongoing",
"Case_End_Date": null,
"Last_Field_Result_Sample_Date": null,
"advisory_level": "Caution"
} Staff names, email addresses and phone numbers are removed from source data before it is stored.