Shadow Cliffs Arroyo: toxic algae advisories
Shadow Cliffs Arroyo, Alameda County. See all Alameda County waters.
What the state's records say
Caution advisory, last posted Dec 31, 2020. 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: Algae that can make toxins may be present. Keep people, children and pets away from algae and scum, and do not let pets drink the water.
Before you go, check the state's official algae page and any signs posted at the water.
Dogs at Shadow Cliffs Arroyo
The state has an advisory on file for Shadow Cliffs Arroyo (Caution advisory), last posted Dec 31, 2020, 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 |
|---|---|
| dog access area | The state's latest record, from Oct 16, 2026, recommends no advisory. |
| dog access area | The state's latest record, from Dec 29, 2022, recommends no advisory. |
| Shadow Cliffs Arroyo, Dog Access area | Caution advisory, last posted Dec 31, 2020. No all-clear recorded. |
| Shadow Cliffs Arroyo | The state's latest record, from Oct 25, 2018, recommends no advisory. |
Advisory history
Every advisory record the state has published for Shadow Cliffs Arroyo, 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 | dog access area | None | No cyano, other algae present. ; Updates from routine monitoring program-organization |
| Sep 18, 2026 | dog access area | None | No cyano, other algae present. ; Updates from routine monitoring program-organization |
| Sep 11, 2026 | dog access area | None | No cyano, other algae present. ; Updates from routine monitoring program-organization |
| Aug 21, 2026 | dog access area | None | No cyano, other algae present. ; Updates from routine monitoring program-organization |
| Aug 14, 2026 | dog access area | None | No cyano, other algae present. ; Updates from routine monitoring program-organization |
| Aug 7, 2026 | dog access area | None | No cyano, other algae present. ; Updates from routine monitoring program-organization |
| Jul 31, 2026 | dog access area | None | No cyano, other algae present. ; Updates from routine monitoring program-organization |
| Jul 24, 2026 | dog access area | None | No cyano, other algae present. ; Updates from routine monitoring program-organization |
| Jul 17, 2026 | dog access area | None | No cyano, other algae present. ; Updates from routine monitoring program-organization |
| Jul 10, 2026 | dog access area | None | No cyano, other algae present. ; Updates from routine monitoring program-organization |
| Jul 3, 2026 | dog access area | None | No cyano, other algae present. ; Updates from routine monitoring program-organization |
| Jun 26, 2026 | dog access area | None | No cyano, other algae present. ; Updates from routine monitoring program-organization |
| Jun 19, 2026 | dog access area | None | No cyano, other algae present. ; Updates from routine monitoring program-organization |
| Jun 12, 2026 | dog access area | None | No cyano, other algae present. ; Updates from routine monitoring program-organization |
| Jun 5, 2026 | dog access area | None | No cyano, other algae present. ; Updates from routine monitoring program-organization |
| Jun 1, 2026 | dog access area | None | No cyano, other algae present. ; Updates from routine monitoring program-organization |
| May 22, 2026 | dog access area | None | No cyano, other algae present. ; Updates from routine monitoring program-organization |
| May 15, 2026 | dog access area | None | No cyano, other algae present. ; Updates from routine monitoring program-organization |
| May 8, 2026 | dog access area | None | No cyano, other algae present. ; Updates from routine monitoring program-organization |
| Apr 24, 2026 | dog access area | None | No cyano, other algae present. ; Updates from routine monitoring program-organization |
| Apr 16, 2026 | dog access area | None | No cyano, other algae present. ; Updates from routine monitoring program-organization |
| Apr 10, 2026 | dog access area | None | No cyano, other algae present. ; Updates from routine monitoring program-organization |
| Mar 20, 2026 | dog access area | None | No cyano, other algae present. ; Updates from routine monitoring program-organization |
| Mar 13, 2026 | dog access area | None | No cyano, other algae present. ; Updates from routine monitoring program-organization |
| Feb 20, 2026 | dog access area | None | No cyano, other algae present. ; Updates from routine monitoring program-organization |
| Feb 6, 2026 | dog access area | None | No cyano, other algae present. ; Updates from routine monitoring program-organization |
| Jan 30, 2026 | dog access area | None | No cyano, other algae present. ; Updates from routine monitoring program-organization |
| Jan 9, 2026 | dog access area | None | No cyano, other algae present. ; Updates from routine monitoring program-organization |
| Dec 12, 2025 | dog access area | None | No cyano, other algae present. ; Updates from routine monitoring program-organization |
| Dec 5, 2025 | dog access area | None | No cyano, other algae present. ; Updates from routine monitoring program-organization |
| Nov 20, 2025 | dog access area | None | No cyano, other algae present. ; Updates from routine monitoring program-organization |
| Nov 7, 2025 | dog access area | None | No cyano, other algae present. ; Updates from routine monitoring program-organization |
| Oct 31, 2025 | dog access area | Caution | No cyano, other algae present. ; Updates from routine monitoring program-organization |
| Oct 23, 2025 | dog access area | Caution | No cyano, other algae present. ; Updates from routine monitoring program-organization |
| Oct 23, 2025 | dog access area | None | No cyano, other algae present. ; Updates from routine monitoring program-organization |
| Oct 17, 2025 | dog access area | None | No cyano, other algae present. ; Updates from routine monitoring program-organization |
| Sep 26, 2025 | dog access area | None | No cyano, other algae present. ; Updates from routine monitoring program-organization |
| Sep 19, 2025 | dog access area | None | No cyano, other algae present. ; Updates from routine monitoring program-organization |
| Sep 5, 2025 | dog access area | None | No cyano, other algae present. ; Updates from routine monitoring program-organization |
| Aug 29, 2025 | dog access area | None | No cyano, other algae present. ; Updates from routine monitoring program-organization |
| Aug 18, 2025 | dog access area | None | No cyano, other algae present. ; Updates from routine monitoring program-organization |
| Aug 8, 2025 | dog access area | None | No cyano, other algae present. ; Updates from routine monitoring program-organization |
| Jul 24, 2025 | dog access area | None | No cyano, other algae present. ; Updates from routine monitoring program-organization |
| Jul 24, 2025 | dog access area | None | No cyano, other algae present. ; Updates from routine monitoring program-organization |
| Jul 18, 2025 | dog access area | None | No cyano, other algae present. ; Updates from routine monitoring program-organization |
| Jul 18, 2025 | dog access area | Caution | No cyano, other algae present. ; Updates from routine monitoring program-organization |
| Jul 11, 2025 | dog access area | Caution | No cyano, other algae present. ; Updates from routine monitoring program-organization |
| Jun 26, 2025 | dog access area | None | No cyano, other algae present. ; Updates from routine monitoring program-organization |
| Jun 20, 2025 | dog access area | None | No cyano, other algae present. ; Updates from routine monitoring program-organization |
| Jun 6, 2025 | dog access area | None | No cyano, other algae present. ; Updates from routine monitoring program-organization |
| Jun 6, 2025 | dog access area | None | No cyano, other algae present. ; Updates from routine monitoring program-organization |
| Jun 2, 2025 | dog access area | None | No cyano, other algae present. ; Updates from routine monitoring program-organization |
| May 19, 2025 | dog access area | None | No cyano, other algae present. ; Updates from routine monitoring program-organization |
| May 2, 2025 | dog access area | General awareness | No cyano, other algae present. ; Updates from routine monitoring program-organization |
| Apr 23, 2025 | dog access area | None | No cyano, other algae present. ; Updates from routine monitoring program-organization |
| Apr 11, 2025 | dog access area | None | No cyano, other algae present. ; Updates from routine monitoring program-organization |
| Apr 4, 2025 | dog access area | None | Updates from routine monitoring program-organization |
| Mar 14, 2025 | dog access area | None | Updates from routine monitoring program-organization |
| Mar 14, 2025 | dog access area | None | Updates from routine monitoring program-organization |
| Mar 7, 2025 | dog access area | None | Updates from routine monitoring program-organization |
| Feb 28, 2025 | dog access area | None | Updates from routine monitoring program-organization |
| Feb 21, 2025 | dog access area | None | Updates from routine monitoring program-organization |
| Feb 6, 2025 | dog access area | None | Updates from routine monitoring program-organization |
| Jan 31, 2025 | dog access area | None | Updates from routine monitoring program-organization |
| Jan 24, 2025 | dog access area | None | Updates from routine monitoring program-organization |
| Jan 17, 2025 | dog access area | None | Updates from routine monitoring program-organization |
| Jan 13, 2025 | dog access area | None | Updates from routine monitoring program-organization |
| Jan 2, 2025 | dog access area | None | Updates from routine monitoring program-organization |
| Dec 20, 2024 | dog access area | None | Updates from routine monitoring program-organization |
| Dec 20, 2024 | dog access area | None | Updates from routine monitoring program-organization |
| Dec 20, 2024 | dog access area | Caution | Updates from routine monitoring program-organization |
| Dec 12, 2024 | dog access area | Caution | Updates from routine monitoring program-organization |
| Dec 6, 2024 | dog access area | Caution | Updates from routine monitoring program-organization |
| Nov 20, 2024 | dog access area | Caution | Updates from routine monitoring program-organization |
| Nov 12, 2024 | dog access area | Caution | Updates from routine monitoring program-organization |
| Oct 31, 2024 | dog access area | Caution | Updates from routine monitoring program-organization |
| Oct 18, 2024 | dog access area | None | Updates from routine monitoring program-organization |
| Oct 11, 2024 | dog access area | None | Updates from routine monitoring program-organization |
| Oct 4, 2024 | dog access area | None | Updates from routine monitoring program-organization |
| Sep 27, 2024 | dog access area | None | Updates from routine monitoring program-organization |
| Sep 20, 2024 | dog access area | None | Updates from routine monitoring program-organization |
| Sep 13, 2024 | dog access area | None | Updates from routine monitoring program-organization |
| Sep 6, 2024 | dog access area | None | Updates from routine monitoring program-organization |
| Aug 26, 2024 | dog access area | None | Updates from routine monitoring program-organization |
| Aug 15, 2024 | dog access area | None | Updates from routine monitoring program-organization |
| Aug 5, 2024 | dog access area | None | Updates from routine monitoring program-organization |
| Aug 2, 2024 | dog access area | None | Updates from routine monitoring program-organization |
| Aug 2, 2024 | dog access area | None | Updates from routine monitoring program-organization |
| Jul 26, 2024 | dog access area | None | Updates from routine monitoring program-organization |
| Jul 22, 2024 | dog access area | None | Updates from routine monitoring program-organization |
| Jul 9, 2024 | dog access area | None | Updates from routine monitoring program-organization |
| Jun 21, 2024 | dog access area | None | Updates from routine monitoring program-organization |
| Jun 21, 2024 | dog access area | None | Updates from routine monitoring program-organization |
| Jun 4, 2024 | dog access area | None | Updates from routine monitoring program-organization |
| May 29, 2024 | dog access area | None | Updates from routine monitoring program-organization |
| May 24, 2024 | dog access area | None | Updates from routine monitoring program-organization |
| May 14, 2024 | dog access area | None | Updates from routine monitoring program-organization |
| May 6, 2024 | dog access area | None | Updates from routine monitoring program-organization |
| Apr 23, 2024 | dog access area | None | Updates from routine monitoring program-organization |
| Apr 16, 2024 | dog access area | None | Updates from routine monitoring program-organization |
| Apr 2, 2024 | dog access area | None | Updates from routine monitoring program-organization |
| Apr 2, 2024 | dog access area | Caution | Updates from routine monitoring program-organization |
| Mar 25, 2024 | dog access area | Caution | Updates from routine monitoring program-organization |
| Mar 19, 2024 | dog access area | Caution | Updates from routine monitoring program-organization |
| Mar 12, 2024 | dog access area | Caution | Updates from routine monitoring program-organization |
| Mar 8, 2024 | dog access area | Caution | Updates from routine monitoring program-organization |
| Mar 1, 2024 | dog access area | Caution | Updates from routine monitoring program-organization |
| Feb 20, 2024 | dog access area | Caution | Updates from routine monitoring program-organization |
| Feb 14, 2024 | dog access area | Caution | Updates from routine monitoring program-organization |
| Jan 29, 2024 | dog access area | Caution | Updates from routine monitoring program-organization |
| Jan 19, 2024 | dog access area | Caution | Updates from routine monitoring program-organization |
| Jan 11, 2024 | dog access area | Caution | Updates from routine monitoring program-organization |
| Jan 2, 2024 | dog access area | Caution | Updates from routine monitoring program-organization |
| Nov 14, 2023 | dog access area | Caution | Updates from routine monitoring program-organization |
| Oct 31, 2023 | dog access area | Caution | Updates from routine monitoring program-organization |
| Oct 24, 2023 | dog access area | Caution | Updates from routine monitoring program-organization |
| Oct 17, 2023 | dog access area | Caution | Updates from routine monitoring program-organization |
| Oct 10, 2023 | dog access area | Caution | Updates from routine monitoring program-organization |
| Oct 2, 2023 | dog access area | Caution | Updates from routine monitoring program-organization |
| Sep 26, 2023 | dog access area | Caution | Updates from routine monitoring program-organization |
| Sep 19, 2023 | dog access area | Caution | Updates from routine monitoring program-organization |
| Sep 12, 2023 | dog access area | Caution | Updates from routine monitoring program-organization |
| Sep 5, 2023 | dog access area | Caution | Updates from routine monitoring program-organization |
| Aug 29, 2023 | dog access area | Caution | Updates from routine monitoring program-organization |
| Aug 29, 2023 | dog access area | None | Updates from routine monitoring program-organization |
| Aug 22, 2023 | dog access area | Caution | Updates from routine monitoring program-organization |
| Aug 15, 2023 | dog access area | Caution | Updates from routine monitoring program-organization |
| Aug 8, 2023 | dog access area | Caution | Updates from routine monitoring program-organization |
| Jul 18, 2023 | dog access area | Caution | Updates from routine monitoring program-organization |
| Jul 11, 2023 | dog access area | Caution | Updates from routine monitoring program-organization |
| Jul 3, 2023 | dog access area | Caution | Updates from routine monitoring program-organization |
| Jun 20, 2023 | dog access area | Caution | Updates from routine monitoring program-organization |
| Jun 20, 2023 | dog access area | None | Updates from routine monitoring program-organization |
| Jun 5, 2023 | dog access area | Caution | Updates from routine monitoring program-organization |
| May 31, 2023 | dog access area | Caution | Updates from routine monitoring program-organization |
| May 24, 2023 | dog access area | Caution | Updates from routine monitoring program-organization |
| May 18, 2023 | dog access area | Caution | Updates from routine monitoring program-organization |
| May 10, 2023 | dog access area | Caution | Updates from routine monitoring program-organization |
| Apr 25, 2023 | dog access area | Caution | Updates from routine monitoring program-organization |
| Apr 4, 2023 | dog access area | Caution | Updates from routine monitoring program-organization |
| Mar 30, 2023 | dog access area | Caution | Updates from routine monitoring program-organization |
| Feb 15, 2023 | dog access area | Caution | Updates from routine monitoring program-organization |
| Feb 15, 2023 | dog access area | Caution | Updates from routine monitoring program-organization |
| Feb 1, 2023 | dog access area | Caution | Updates from routine monitoring program-organization |
| Jan 24, 2023 | dog access area | Danger | Updates from routine monitoring program-organization |
| Dec 29, 2022 | dog access area | Danger | Updates from routine monitoring program-organization |
| Dec 29, 2022 | dog access area | None | End date recorded: Dec 31, 2022. Under investigation |
| Dec 29, 2022 | dog access area | None | Under investigation |
| Dec 20, 2022 | dog access area | Danger | Floating/planktonic bloom observed; Lake-wide advisory; Updates from routine monitoring program-organization |
| Dec 7, 2022 | dog access area | Danger | Floating/planktonic bloom observed; Lake-wide advisory; Updates from routine monitoring program-organization |
| Nov 22, 2022 | dog access area | Caution | Floating/planktonic bloom observed; Lake-wide advisory; Updates from routine monitoring program-organization |
| Oct 18, 2022 | dog access area | Caution | Floating/planktonic bloom observed; Lake-wide advisory; Updates from routine monitoring program-organization |
| Oct 4, 2022 | dog access area | Caution | Floating/planktonic bloom observed; Lake-wide advisory; Updates from routine monitoring program-organization |
| Aug 23, 2022 | dog access area | Caution | Floating/planktonic bloom observed; Lake-wide advisory; Updates from routine monitoring program-organization |
| Aug 19, 2022 | dog access area | Caution | Floating/planktonic bloom observed; Lake-wide advisory; Updates from routine monitoring program-organization |
| Jul 26, 2022 | dog access area | Caution | Updates from routine monitoring program-organization |
| Jul 22, 2022 | dog access area | Caution | Updates from routine monitoring program-organization |
| Jul 8, 2022 | dog access area | Caution | Updates from routine monitoring program-organization |
| Jul 1, 2022 | dog access area | Caution | Updates from routine monitoring program-organization |
| Jun 22, 2022 | dog access area | Caution | Updates from routine monitoring program-organization |
| Jun 14, 2022 | dog access area | Caution | Updates from routine monitoring program-organization |
| Jun 3, 2022 | dog access area | Caution | Updates from routine monitoring program-organization |
| May 18, 2022 | dog access area | Caution | Updates from routine monitoring program-organization |
| May 6, 2022 | dog access area | None | Updates from routine monitoring program-organization |
| Dec 31, 2020 | Shadow Cliffs Arroyo, Dog Access area | Caution | |
| Oct 25, 2018 | Shadow Cliffs Arroyo | None |
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.