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California / Waters /

Lake Temescal

Lake in California, near Oakland

Current status

Algal bloom advisory

An official advisory about an algal bloom (cyanobacteria) is listed for this water. Open the report for its source, dates and advice. This status since . Why this status, and its source

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.

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About this status

Algal bloom advisory: official algal bloom advisory listed; shown while the authority keeps it in place

Source: California State Water Resources Control Board (FHAB program) via Surface Water - Freshwater Harmful Algal Blooms, record 3965-2322, reported Jan 13, 2023, 12:00 AM PST, retrieved 2026-11-06 03:07 UTC · Original notice · Updated

Reports behind this status

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

Reports behind the status of Lake Temescal, newest first
WhenReportStatus
California State Water Resources Control Board (FHAB program) · Lake Temescal · Algae advisory · volume not reported report · notice · mapto Nov 12, 8:00 PM PST

Sources: Surface Water - Freshwater Harmful Algal Blooms, retrieved 2026-11-06 03:07 UTC. A report's record id and times show when you hover or focus its "report" link.

Advice in the reports

California State Water Resources Control Board (FHAB program) · Jan 13, 2023 · Current status: sets this water's status now

“Danger advisory for cyanobacteria (harmful algal bloom), as recommended in the FHAB report”

The last 90 days

Last 90 days, hour by hour. Red: discharge or advisory reported. Amber: caution. Hatched amber: end not confirmed. Plum: algal bloom advisory. Red or amber with a light line inside: beach advisory or caution. Dotted: monthly report (days with discharge, dates not given). Grey: no current status on the water outline. Purple hatching: a status resting on a source that could not be checked on schedule.

Algal bloom advisories: 1 period

  • Algal bloom advisory: to the latest update
    1 report: California State Water Resources Control Board (FHAB program) 1
    Show records

    The records are also in the report table on this page.

Source: DirtyWaterWatch calculations using the reports named above and the published status rules. Updated 2026-11-06 09:03 UTC.

Reported discharges over time

  • Hours with a discharge or advisory status on Lake Temescal in California, last 12 months8,165Reported on Lake Temescal in California: 0 · Arriving from outfalls upstream, estimated: 0 · Official advisories (beach, algal bloom): 8,165December 2025 to November 2026Red hours by the map's rules: each discharge to its reported end plus the state's post-discharge period; overlapping hours count once.
  • 2026 season with a discharge or advisory status on Lake Temescal in California100%May to October 2026Share of May 1 to October 31 hours with red status by the map's rules, of the hours a source covered.
  • Records behind the last-90-days strip for Lake Temescal in California1Reported on Lake Temescal in California: 1 · Arriving from outfalls upstream, estimated: 0last 90 daysEvery distinct record the strip lists for its red, yellow and unresolved hours, notices and unresolved reports included; counted as the strip counts them.

Hours with a discharge or advisory status per month

Hours when this water had a discharge or advisory status under DirtyWaterWatch rules.

  • Discharge or advisory reported

5 discharges reported to last more than 31 days are counted as 31 days.

Source: ca-swrcb-fhab. Records cover March 4, 2016 to November 6, 2026.

Show table

Hours with a discharge or advisory status per year

Hours with a discharge or advisory status each year under DirtyWaterWatch rules; 2026 to date.

  • Discharge or advisory reported
  • Incomplete source coverage

5 discharges reported to last more than 31 days are counted as 31 days.

Source: ca-swrcb-fhab. Records cover March 4, 2016 to November 6, 2026.

Show table

Share of the May to October season with a discharge or advisory status

Share of the hours from May 1 to October 31 with a discharge or advisory status under DirtyWaterWatch rules.

  • Discharge or advisory reported

5 discharges reported to last more than 31 days are counted as 31 days.

Source: ca-swrcb-fhab. Records cover March 4, 2016 to November 6, 2026.

Show table
How these charts are counted

We count each discharge once. Where a source publishes notices and confirmed reports, we use confirmed reports for an operator's month when available; otherwise we use notices. We combine revisions and exclude duplicate state reports copied by the U.S. Environmental Protection Agency (EPA). Monthly and yearly totals appear separately. Status hours follow this site's rules. Shaded gaps mean missing coverage, not zero discharges.

  • ca-swrcb-fhab: records from March 4, 2016 to the latest update

Reports linked to Lake Temescal

Reports linked to Lake Temescal, newest first
WhenReportStatus
California State Water Resources Control Board (FHAB program) · Lake Temescal · Algae advisory · volume not reported report · notice · mapto Nov 12, 8:00 PM PST
to Dec 31 ’22California State Water Resources Control Board (FHAB program) · East Bay Regional Parks · Algae advisory · volume not reported report · notice · maplifted
to Dec 31 ’20California State Water Resources Control Board (FHAB program) · Lake Temescal · Algae advisory · volume not reported report · notice · maplifted
to Dec 31 ’19California State Water Resources Control Board (FHAB program) · Lake Temescal · Algae advisory · volume not reported report · notice · maplifted
to Dec 31 ’17California State Water Resources Control Board (FHAB program) · Lake Temescal · Algae advisory · volume not reported report · notice · maplifted
to Dec 31 ’16California State Water Resources Control Board (FHAB program) · Lake Temescal · Algae advisory · volume not reported report · notice · maplifted

Download these reports as CSV

All reports in California by year: 2023 (1 here) · 2022 (1 here) · 2020 (1 here) · 2019 (1 here) · 2017 (1 here) · 2016 (1 here)

Wastewater outlets on this water

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

No wastewater outlet in our records is linked to this water.

Boat launches

No public boat launch is listed in our records for this water.

Nearby waters

Sources covering this water

6 records linked to this water. Updated .