Lake Anza: toxic algae advisories
Lake Anza, Contra Costa County. See all Contra Costa County waters.
What the state's records say
Danger advisory, last posted Jul 16, 2021. No all-clear recorded.
4 reported spots here have an advisory with no all-clear recorded.
Reporting is voluntary, so the state may not have recorded an end even if conditions changed. Check posted signs and the official map.
What this level asks: Toxins may be at levels that can seriously harm people and animals. Stay out of the water and keep children and pets away from the water and the shore.
Before you go, check the state's official algae page and any signs posted at the water.
Dogs at Lake Anza
The state has an advisory on file for Lake Anza (Danger advisory), last posted Jul 16, 2021, and no all-clear recorded. Keep your dog out of the water and away from scum on the shore until the state records an end.
Reported spots
The state records each report at a spot, such as a beach or a boat ramp. Each spot's latest deciding record:
| Spot | Status |
|---|---|
| Lake Anza | The state's latest record, from Oct 16, 2026, recommends no advisory. |
| lake-wide | The state's latest record, from Dec 28, 2022, recommends no advisory. |
| Lake Anza | Caution advisory, last posted Jul 16, 2021. No all-clear recorded. |
| Lake Anza | Danger advisory, last posted Dec 31, 2020. No all-clear recorded. |
| Lake Anza | Danger advisory, last posted Oct 2, 2019. No all-clear recorded. |
| Lake Anza | The state's latest record, from Dec 7, 2018, recommends no advisory. |
| Lake Anza | The state's latest record, from Aug 27, 2018, recommends no advisory. |
| Lake Anza | The state's latest record, from Mar 20, 2018, recommends no advisory. |
| Lake Anza | The state's latest record, from Dec 22, 2017, recommends no advisory. |
| Lake Anza | The state's latest record, from Aug 31, 2017, recommends no advisory. |
| Lake Anza | Danger advisory, last posted Dec 8, 2016. No all-clear recorded. |
Advisory history
Every advisory record the state has published for Lake Anza, newest first. "None" is the state's record that no advisory was recommended on that date. "NA" records do not change a status.
| Date | Spot | State's level | Notes |
|---|---|---|---|
| Oct 16, 2026 | Lake Anza | None | Lake-wide advisory; Updates from routine monitoring program-organization |
| Oct 9, 2026 | Lake Anza | None | Lake-wide advisory; Updates from routine monitoring program-organization |
| Oct 1, 2026 | Lake Anza | None | Lake-wide advisory; Updates from routine monitoring program-organization |
| Sep 25, 2026 | Lake Anza | None | Lake-wide advisory; Updates from routine monitoring program-organization |
| Sep 18, 2026 | Lake Anza | None | Lake-wide advisory; Updates from routine monitoring program-organization |
| Sep 11, 2026 | Lake Anza | None | Lake-wide advisory; Updates from routine monitoring program-organization |
| Sep 3, 2026 | Lake Anza | None | Lake-wide advisory; Updates from routine monitoring program-organization |
| Aug 31, 2026 | Lake Anza | None | Lake-wide advisory; Updates from routine monitoring program-organization |
| Aug 21, 2026 | Lake Anza | None | Lake-wide advisory; Updates from routine monitoring program-organization |
| Aug 14, 2026 | Lake Anza | None | Lake-wide advisory; Updates from routine monitoring program-organization |
| Aug 7, 2026 | Lake Anza | None | Lake-wide advisory; Updates from routine monitoring program-organization |
| Jul 31, 2026 | Lake Anza | None | Lake-wide advisory; Updates from routine monitoring program-organization |
| Jul 24, 2026 | Lake Anza | None | Lake-wide advisory; Updates from routine monitoring program-organization |
| Jul 17, 2026 | Lake Anza | None | Lake-wide advisory; Updates from routine monitoring program-organization |
| Jul 10, 2026 | Lake Anza | None | Lake-wide advisory; Updates from routine monitoring program-organization |
| Jul 3, 2026 | Lake Anza | None | Lake-wide advisory; Updates from routine monitoring program-organization |
| Jun 26, 2026 | Lake Anza | None | Lake-wide advisory; Updates from routine monitoring program-organization |
| Jun 19, 2026 | Lake Anza | None | Lake-wide advisory; Updates from routine monitoring program-organization |
| Jun 12, 2026 | Lake Anza | None | Lake-wide advisory; Updates from routine monitoring program-organization |
| Jun 5, 2026 | Lake Anza | None | Lake-wide advisory; Updates from routine monitoring program-organization |
| Jun 1, 2026 | Lake Anza | None | Lake-wide advisory; Updates from routine monitoring program-organization |
| May 22, 2026 | Lake Anza | None | Lake-wide advisory; Updates from routine monitoring program-organization |
| May 15, 2026 | Lake Anza | None | Lake-wide advisory; Updates from routine monitoring program-organization |
| May 8, 2026 | Lake Anza | None | Lake-wide advisory; Updates from routine monitoring program-organization |
| May 1, 2026 | Lake Anza | None | Lake-wide advisory; Updates from routine monitoring program-organization |
| Apr 16, 2026 | Lake Anza | None | Lake-wide advisory; Updates from routine monitoring program-organization |
| Apr 16, 2026 | Lake Anza | None | Lake-wide advisory; Updates from routine monitoring program-organization |
| Apr 10, 2026 | Lake Anza | None | Lake-wide advisory; Updates from routine monitoring program-organization |
| Mar 27, 2026 | Lake Anza | None | Lake-wide advisory; Updates from routine monitoring program-organization |
| Mar 20, 2026 | Lake Anza | None | Lake-wide advisory; Updates from routine monitoring program-organization |
| Mar 13, 2026 | Lake Anza | None | Lake-wide advisory; Updates from routine monitoring program-organization |
| Mar 6, 2026 | Lake Anza | None | Lake-wide advisory; Updates from routine monitoring program-organization |
| Feb 26, 2026 | Lake Anza | None | Lake-wide advisory; Updates from routine monitoring program-organization |
| Feb 6, 2026 | Lake Anza | None | Lake-wide advisory; Updates from routine monitoring program-organization |
| Jan 23, 2026 | Lake Anza | None | Lake-wide advisory; Updates from routine monitoring program-organization |
| Jan 16, 2026 | Lake Anza | Caution | Lake-wide advisory; Updates from routine monitoring program-organization |
| Jan 9, 2026 | Lake Anza | Caution | Lake-wide advisory; Updates from routine monitoring program-organization |
| Jan 9, 2026 | Lake Anza | Caution | Lake-wide advisory; Updates from routine monitoring program-organization |
| Jan 9, 2026 | Lake Anza | Caution | Lake-wide advisory; Updates from routine monitoring program-organization |
| Nov 20, 2025 | Lake Anza | Caution | Lake-wide advisory; Updates from routine monitoring program-organization |
| Nov 20, 2025 | Lake Anza | Caution | Lake-wide advisory; Updates from routine monitoring program-organization |
| Oct 31, 2025 | Lake Anza | Caution | Lake-wide advisory; Updates from routine monitoring program-organization |
| Oct 23, 2025 | Lake Anza | None | Lake-wide advisory; Updates from routine monitoring program-organization |
| Oct 17, 2025 | Lake Anza | None | Lake-wide advisory; Updates from routine monitoring program-organization |
| Oct 10, 2025 | Lake Anza | None | Lake-wide advisory; Updates from routine monitoring program-organization |
| Sep 26, 2025 | Lake Anza | None | Lake-wide advisory; Updates from routine monitoring program-organization |
| Sep 19, 2025 | Lake Anza | Caution | Lake-wide advisory; Updates from routine monitoring program-organization |
| Sep 12, 2025 | Lake Anza | Caution | Lake-wide advisory; Updates from routine monitoring program-organization |
| Sep 5, 2025 | Lake Anza | Caution | Lake-wide advisory; Updates from routine monitoring program-organization |
| Aug 29, 2025 | Lake Anza | Caution | Lake-wide advisory; Updates from routine monitoring program-organization |
| Aug 22, 2025 | Lake Anza | Caution | Lake-wide advisory; Updates from routine monitoring program-organization |
| Aug 8, 2025 | Lake Anza | Caution | Lake-wide advisory; Updates from routine monitoring program-organization |
| Jul 31, 2025 | Lake Anza | Caution | Lake-wide advisory; Updates from routine monitoring program-organization |
| Jul 24, 2025 | Lake Anza | Caution | Lake-wide advisory; Updates from routine monitoring program-organization |
| Jul 18, 2025 | Lake Anza | Caution | Lake-wide advisory; Updates from routine monitoring program-organization |
| Jul 11, 2025 | Lake Anza | Caution | Lake-wide advisory; Updates from routine monitoring program-organization |
| Jun 26, 2025 | Lake Anza | Caution | Lake-wide advisory; Updates from routine monitoring program-organization |
| Jun 20, 2025 | Lake Anza | Caution | Lake-wide advisory; Updates from routine monitoring program-organization |
| Jun 13, 2025 | Lake Anza | Caution | Lake-wide advisory; Updates from routine monitoring program-organization |
| Jun 6, 2025 | Lake Anza | Caution | Lake-wide advisory; Updates from routine monitoring program-organization |
| Jun 2, 2025 | Lake Anza | Caution | Lake-wide advisory; Updates from routine monitoring program-organization |
| May 19, 2025 | Lake Anza | None | Lake-wide advisory; Updates from routine monitoring program-organization |
| May 9, 2025 | Lake Anza | None | Lake-wide advisory; Updates from routine monitoring program-organization |
| May 2, 2025 | Lake Anza | None | Lake-wide advisory; Updates from routine monitoring program-organization |
| Apr 28, 2025 | Lake Anza | None | Lake-wide advisory; Updates from routine monitoring program-organization |
| Apr 23, 2025 | Lake Anza | None | Lake-wide advisory; Updates from routine monitoring program-organization |
| Apr 23, 2025 | Lake Anza | None | Lake-wide advisory; Updates from routine monitoring program-organization |
| Mar 28, 2025 | Lake Anza | None | Lake-wide advisory; Updates from routine monitoring program-organization |
| Mar 21, 2025 | Lake Anza | None | Lake-wide advisory; Updates from routine monitoring program-organization |
| Mar 14, 2025 | Lake Anza | None | Lake-wide advisory; Updates from routine monitoring program-organization |
| Mar 7, 2025 | Lake Anza | None | Lake-wide advisory; Updates from routine monitoring program-organization |
| Feb 21, 2025 | Lake Anza | None | Lake-wide advisory; Updates from routine monitoring program-organization |
| Feb 6, 2025 | Lake Anza | None | Lake-wide advisory; Updates from routine monitoring program-organization |
| Jan 31, 2025 | Lake Anza | None | Lake-wide advisory; Updates from routine monitoring program-organization |
| Jan 17, 2025 | Lake Anza | None | Lake-wide advisory; Updates from routine monitoring program-organization |
| Jan 13, 2025 | Lake Anza | Caution | Lake-wide advisory; Updates from routine monitoring program-organization |
| Jan 2, 2025 | Lake Anza | Caution | Lake-wide advisory; Updates from routine monitoring program-organization |
| Dec 20, 2024 | Lake Anza | Caution | Lake-wide advisory; Updates from routine monitoring program-organization |
| Dec 12, 2024 | Lake Anza | Caution | Lake-wide advisory; Updates from routine monitoring program-organization |
| Dec 6, 2024 | Lake Anza | Caution | Lake-wide advisory; Updates from routine monitoring program-organization |
| Dec 2, 2024 | Lake Anza | Danger | Lake-wide advisory; Updates from routine monitoring program-organization |
| Nov 12, 2024 | Lake Anza | Danger | Lake-wide advisory; Updates from routine monitoring program-organization |
| Oct 31, 2024 | Lake Anza | Danger | Lake-wide advisory; Updates from routine monitoring program-organization |
| Oct 18, 2024 | Lake Anza | Danger | Lake-wide advisory; Updates from routine monitoring program-organization |
| Oct 11, 2024 | Lake Anza | Danger | Lake-wide advisory; Updates from routine monitoring program-organization |
| Oct 4, 2024 | Lake Anza | Danger | Lake-wide advisory; Updates from routine monitoring program-organization |
| Sep 27, 2024 | Lake Anza | Danger | Lake-wide advisory; Updates from routine monitoring program-organization |
| Sep 20, 2024 | Lake Anza | Danger | Lake-wide advisory; Updates from routine monitoring program-organization |
| Sep 13, 2024 | Lake Anza | Danger | Lake-wide advisory; Updates from routine monitoring program-organization |
| Sep 6, 2024 | Lake Anza | Danger | Lake-wide advisory; Updates from routine monitoring program-organization |
| Sep 6, 2024 | Lake Anza | Danger | Lake-wide advisory; Updates from routine monitoring program-organization |
| Aug 30, 2024 | Lake Anza | Danger | Lake-wide advisory; Updates from routine monitoring program-organization |
| Aug 26, 2024 | Lake Anza | Danger | Lake-wide advisory; Updates from routine monitoring program-organization |
| Aug 15, 2024 | Lake Anza | Danger | Lake-wide advisory; Updates from routine monitoring program-organization |
| Aug 9, 2024 | Lake Anza | Danger | Lake-wide advisory; Updates from routine monitoring program-organization |
| Aug 2, 2024 | Lake Anza | Danger | Lake-wide advisory; Updates from routine monitoring program-organization |
| Aug 2, 2024 | Lake Anza | Danger | Lake-wide advisory; Updates from routine monitoring program-organization |
| Jul 26, 2024 | Lake Anza | Danger | Lake-wide advisory; Updates from routine monitoring program-organization |
| Jul 22, 2024 | Lake Anza | Danger | Lake-wide advisory; Updates from routine monitoring program-organization |
| Jul 8, 2024 | Lake Anza | Danger | Lake-wide advisory; Updates from routine monitoring program-organization |
| Jul 3, 2024 | Lake Anza | Danger | Lake-wide advisory; Updates from routine monitoring program-organization |
| Jun 24, 2024 | Lake Anza | Danger | Lake-wide advisory; Updates from routine monitoring program-organization |
| Jun 21, 2024 | Lake Anza | Danger | Lake-wide advisory; Updates from routine monitoring program-organization |
| Jun 3, 2024 | Lake Anza | Caution | Lake-wide advisory; Updates from routine monitoring program-organization |
| May 28, 2024 | Lake Anza | Caution | Lake-wide advisory; Updates from routine monitoring program-organization |
| May 24, 2024 | Lake Anza | Caution | Lake-wide advisory; Updates from routine monitoring program-organization |
| May 14, 2024 | Lake Anza | Visual observation | Alert-detached mats observed; Updates from routine monitoring program-organization |
| May 6, 2024 | Lake Anza | Visual observation | Alert-detached mats observed; Updates from routine monitoring program-organization |
| Apr 29, 2024 | Lake Anza | Caution | Alert-detached mats observed; Updates from routine monitoring program-organization |
| Apr 22, 2024 | Lake Anza | Caution | Alert-detached mats observed; Updates from routine monitoring program-organization |
| Apr 15, 2024 | Lake Anza | Caution | Alert-detached mats observed; Updates from routine monitoring program-organization |
| Apr 8, 2024 | Lake Anza | Caution | Alert-detached mats observed; Updates from routine monitoring program-organization |
| Apr 2, 2024 | Lake Anza | Caution | Alert-detached mats observed; Updates from routine monitoring program-organization |
| Mar 26, 2024 | Lake Anza | Caution | Alert-detached mats observed; Updates from routine monitoring program-organization |
| Mar 20, 2024 | Lake Anza | Caution | Alert-detached mats observed; Updates from routine monitoring program-organization |
| Mar 11, 2024 | Lake Anza | Caution | Alert-detached mats observed; Updates from routine monitoring program-organization |
| Mar 8, 2024 | Lake Anza | Caution | Alert-detached mats observed; Updates from routine monitoring program-organization |
| Feb 22, 2024 | Lake Anza | Caution | Alert-detached mats observed; Updates from routine monitoring program-organization |
| Feb 13, 2024 | Lake Anza | Caution | Alert-detached mats observed; Updates from routine monitoring program-organization |
| Feb 9, 2024 | Lake Anza | None | Alert-detached mats observed; Updates from routine monitoring program-organization |
| Jan 30, 2024 | Lake Anza | None | Alert-detached mats observed; Updates from routine monitoring program-organization |
| Jan 19, 2024 | Lake Anza | None | Alert-detached mats observed; Updates from routine monitoring program-organization |
| Jan 11, 2024 | Lake Anza | Caution | Alert-detached mats observed; Updates from routine monitoring program-organization |
| Jan 5, 2024 | Lake Anza | Caution | Alert-detached mats observed; Updates from routine monitoring program-organization |
| Dec 27, 2023 | Lake Anza | Warning | Alert-detached mats observed; Updates from routine monitoring program-organization |
| Dec 27, 2023 | Lake Anza | Caution | Alert-detached mats observed; Updates from routine monitoring program-organization |
| Dec 27, 2023 | Lake Anza | Caution | Alert-detached mats observed; Updates from routine monitoring program-organization |
| Dec 11, 2023 | Lake Anza | Caution | Alert-detached mats observed; Updates from routine monitoring program-organization |
| Nov 29, 2023 | Lake Anza | Caution | Alert-detached mats observed; Updates from routine monitoring program-organization |
| Nov 15, 2023 | Lake Anza | Caution | Alert-detached mats observed; Updates from routine monitoring program-organization |
| Oct 30, 2023 | Lake Anza | Caution | Alert-detached mats observed; Updates from routine monitoring program-organization |
| Oct 11, 2023 | Lake Anza | Caution | Alert-detached mats observed; Updates from routine monitoring program-organization |
| Oct 11, 2023 | Lake Anza | Danger | Alert-detached mats observed; Updates from routine monitoring program-organization |
| Oct 3, 2023 | Lake Anza | Danger | Alert-detached mats observed; Updates from routine monitoring program-organization |
| Sep 27, 2023 | Lake Anza | Danger | Alert-detached mats observed; Updates from routine monitoring program-organization |
| Sep 18, 2023 | Lake Anza | Danger | Alert-detached mats observed; Updates from routine monitoring program-organization |
| Sep 11, 2023 | Lake Anza | Caution | Alert-detached mats observed; Updates from routine monitoring program-organization |
| Sep 5, 2023 | Lake Anza | Caution | Alert-detached mats observed; Updates from routine monitoring program-organization |
| Aug 30, 2023 | Lake Anza | Caution | Alert-detached mats observed; Updates from routine monitoring program-organization |
| Aug 30, 2023 | Lake Anza | Caution | Alert-detached mats observed; Updates from routine monitoring program-organization |
| Aug 21, 2023 | Lake Anza | Caution | Alert-detached mats observed; Updates from routine monitoring program-organization |
| Aug 14, 2023 | Lake Anza | Caution | Alert-detached mats observed; Updates from routine monitoring program-organization |
| Aug 7, 2023 | Lake Anza | Caution | Alert-detached mats observed; Updates from routine monitoring program-organization |
| Jul 31, 2023 | Lake Anza | Caution | Alert-detached mats observed; Updates from routine monitoring program-organization |
| Jul 24, 2023 | Lake Anza | Caution | Alert-detached mats observed; Updates from routine monitoring program-organization |
| Jul 17, 2023 | Lake Anza | Caution | Alert-detached mats observed; Updates from routine monitoring program-organization |
| Jul 10, 2023 | Lake Anza | Caution | Alert-detached mats observed; Updates from routine monitoring program-organization |
| Jul 5, 2023 | Lake Anza | Caution | Alert-detached mats observed; Updates from routine monitoring program-organization |
| Jun 26, 2023 | Lake Anza | None | Alert-detached mats observed; Updates from routine monitoring program-organization |
| Jun 20, 2023 | Lake Anza | None | Alert-detached mats observed; Updates from routine monitoring program-organization |
| Jun 5, 2023 | Lake Anza | Caution | Alert-detached mats observed; Updates from routine monitoring program-organization |
| May 30, 2023 | Lake Anza | Caution | Alert-detached mats observed; Updates from routine monitoring program-organization |
| May 22, 2023 | Lake Anza | Caution | Alert-detached mats observed; Updates from routine monitoring program-organization |
| May 15, 2023 | Lake Anza | Caution | Alert-detached mats observed; Updates from routine monitoring program-organization |
| May 8, 2023 | Lake Anza | Caution | Alert-detached mats observed; Updates from routine monitoring program-organization |
| May 4, 2023 | Lake Anza | Caution | Alert-detached mats observed; Updates from routine monitoring program-organization |
| May 4, 2023 | Lake Anza | None | Updates from routine monitoring program-organization |
| Apr 24, 2023 | Lake Anza | None | Updates from routine monitoring program-organization |
| Apr 17, 2023 | Lake Anza | None | Updates from routine monitoring program-organization |
| Apr 10, 2023 | Lake Anza | Caution | Updates from routine monitoring program-organization |
| Apr 4, 2023 | Lake Anza | None | Updates from routine monitoring program-organization |
| Mar 1, 2023 | Lake Anza | None | Updates from routine monitoring program-organization |
| Feb 1, 2023 | Lake Anza | None | Updates from routine monitoring program-organization |
| Jan 26, 2023 | Lake Anza | None | Updates from routine monitoring program-organization |
| Dec 28, 2022 | Lake Anza | None | Updates from routine monitoring program-organization |
| Dec 28, 2022 | lake-wide | None | End date recorded: Dec 31, 2022. No cyano, other algae present. |
| Dec 28, 2022 | lake-wide | None | No cyano, other algae present. |
| Nov 29, 2022 | lake-wide | None | No cyano, other algae present. |
| Nov 21, 2022 | lake-wide | None | No cyano, other algae present. |
| Nov 15, 2022 | lake-wide | None | No cyano, other algae present. |
| Nov 9, 2022 | lake-wide | None | No cyano, other algae present. |
| Oct 25, 2022 | lake-wide | None | No cyano, other algae present. |
| Oct 18, 2022 | lake-wide | None | No cyano, other algae present. |
| Oct 4, 2022 | lake-wide | Caution | No cyano, other algae present. |
| Oct 4, 2022 | lake-wide | Caution | No cyano, other algae present. |
| Sep 20, 2022 | lake-wide | None | No cyano, other algae present. |
| Aug 30, 2022 | lake-wide | None | No cyano, other algae present. |
| Aug 16, 2022 | lake-wide | None | No cyano, other algae present. |
| Aug 10, 2022 | lake-wide | None | No cyano, other algae present. |
| Aug 3, 2022 | lake-wide | None | No cyano, other algae present. |
| Jul 26, 2022 | lake-wide | None | No cyano, other algae present. |
| Jul 22, 2022 | lake-wide | None | No cyano, other algae present. |
| Jul 7, 2022 | lake-wide | None | No cyano, other algae present. |
| Jul 1, 2022 | lake-wide | None | No cyano, other algae present. |
| Jun 21, 2022 | lake-wide | None | No cyano, other algae present. |
| May 31, 2022 | lake-wide | None | No cyano, other algae present. |
| May 25, 2022 | lake-wide | None | No cyano, other algae present. |
| May 18, 2022 | lake-wide | None | No cyano, other algae present. |
| May 11, 2022 | lake-wide | None | No cyano, other algae present. |
| May 6, 2022 | lake-wide | None | No cyano, other algae present. |
| Jul 16, 2021 | Lake Anza | Caution | Advisory based on visual and toxins |
| Dec 31, 2020 | Lake Anza | Danger | Advisory based on visual and toxins |
| Oct 2, 2019 | Lake Anza | Danger | |
| Dec 7, 2018 | Lake Anza | None | |
| Aug 27, 2018 | Lake Anza | None | |
| Mar 20, 2018 | Lake Anza | None | |
| Dec 22, 2017 | Lake Anza | None | |
| Aug 31, 2017 | Lake Anza | None | |
| Dec 8, 2016 | Lake Anza | Danger |
Source
Advisory data: California State Water Resources Control Board, Freshwater Harmful Algal Bloom Program, via data.ca.gov (public domain). Advisories are recommendations; reporting is voluntary and incomplete. The state's data. An advisory ends only when the state records a later "None" (no advisory recommended) at the same spot, or an end date. A blank end date is unknown.