Old River: toxic algae advisories
Old River, Contra Costa County. See all Contra Costa County waters.
What the state's records say
Caution advisory, last posted Sep 17, 2026. No all-clear recorded.
3 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: 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 Old River
The state has an advisory on file for Old River (Caution advisory), last posted Sep 17, 2026, 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 |
|---|---|
| at Clifton Court Intake (ORI) | Visual observation, last posted Sep 17, 2026. No all-clear recorded. |
| Old River downstream of Clifton Court Forebay Intake (WCI) | Visual observation, last posted May 29, 2025. No all-clear recorded. |
| at Clifton Court Intake (ORI) | The state's latest record, from Dec 20, 2022, recommends no advisory. |
| at Kings Island | Caution advisory, last posted Jun 17, 2021. No all-clear recorded. |
| Old River at Confluence of West Canal, North of Clifton Court Forebay | The state's latest record, from Dec 4, 2018, recommends no advisory. |
| Old River, near Clifton Court Forebay Intake | The state's latest record, from Dec 4, 2018, recommends no advisory. |
Advisory history
Every advisory record the state has published for Old River, 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 |
|---|---|---|---|
| Sep 17, 2026 | at Clifton Court Intake (ORI) | Visual observation | Updates from routine monitoring program-organization; Visual monitoring only-present bloom |
| Aug 21, 2026 | at Clifton Court Intake (ORI) | Visual observation | Updates from routine monitoring program-organization; Visual monitoring only-present bloom |
| Jul 16, 2026 | at Clifton Court Intake (ORI) | Visual observation | Updates from routine monitoring program-organization; Visual monitoring only-present bloom |
| Jun 18, 2026 | at Clifton Court Intake (ORI) | Visual observation | Updates from routine monitoring program-organization; Visual monitoring only-present bloom |
| May 27, 2026 | at Clifton Court Intake (ORI) | None | Updates from routine monitoring program-organization; Visual monitoring only-absent bloom |
| Apr 29, 2026 | at Clifton Court Intake (ORI) | None | Updates from routine monitoring program-organization; Visual monitoring only-absent bloom |
| Feb 6, 2026 | at Clifton Court Intake (ORI) | None | Updates from routine monitoring program-organization; Visual monitoring only-absent bloom |
| Jan 15, 2026 | at Clifton Court Intake (ORI) | None | Updates from routine monitoring program-organization; Visual monitoring only-absent bloom |
| Dec 12, 2025 | at Clifton Court Intake (ORI) | None | Updates from routine monitoring program-organization; Visual monitoring only-absent bloom |
| Nov 20, 2025 | at Clifton Court Intake (ORI) | None | Updates from routine monitoring program-organization; Visual monitoring only-absent bloom |
| Oct 16, 2025 | at Clifton Court Intake (ORI) | Visual observation | Updates from routine monitoring program-organization; Visual monitoring only-present bloom |
| Sep 24, 2025 | at Clifton Court Intake (ORI) | Visual observation | Updates from routine monitoring program-organization; Visual monitoring only-present bloom |
| Aug 19, 2025 | at Clifton Court Intake (ORI) | Visual observation | Updates from routine monitoring program-organization; Visual monitoring only-present bloom |
| Jul 25, 2025 | at Clifton Court Intake (ORI) | Visual observation | Updates from routine monitoring program-organization; Visual monitoring only-present bloom |
| Jun 30, 2025 | at Clifton Court Intake (ORI) | Visual observation | Updates from routine monitoring program-organization; Visual monitoring only-present bloom |
| May 29, 2025 | Old River downstream of Clifton Court Forebay Intake (WCI) | Visual observation | Updates from routine monitoring program-organization; Visual monitoring only-present bloom |
| May 29, 2025 | Old River downstream of Clifton Court Forebay Intake (WCI) | NA - refer to Report Details | Updates from routine monitoring program-organization; Visual monitoring only-present bloom |
| May 29, 2025 | at Clifton Court Intake (ORI) | NA - refer to Report Details | Updates from routine monitoring program-organization; Visual monitoring only-present bloom |
| Apr 18, 2025 | at Clifton Court Intake (ORI) | NA - refer to Report Details | Updates from routine monitoring program-organization; Visual monitoring only-absent bloom |
| Mar 25, 2025 | at Clifton Court Intake (ORI) | NA - refer to Report Details | Updates from routine monitoring program-organization; Visual monitoring only-absent bloom |
| Feb 19, 2025 | at Clifton Court Intake (ORI) | NA - refer to Report Details | Updates from routine monitoring program-organization; Visual monitoring only-absent bloom |
| Dec 17, 2024 | at Clifton Court Intake (ORI) | NA - refer to Report Details | Updates from routine monitoring program-organization; Visual monitoring only-absent bloom |
| Nov 13, 2024 | at Clifton Court Intake (ORI) | Visual observation | Updates from routine monitoring program-organization; Visual monitoring only-present bloom |
| Nov 13, 2024 | at Clifton Court Intake (ORI) | Visual observation | Updates from routine monitoring program-organization; Visual monitoring only-present bloom |
| Oct 18, 2024 | at Clifton Court Intake (ORI) | Visual observation | Updates from routine monitoring program-organization; Visual monitoring only-present bloom |
| Oct 11, 2024 | at Clifton Court Intake (ORI) | Visual observation | Updates from routine monitoring program-organization; Visual monitoring only-present bloom |
| Aug 8, 2024 | at Clifton Court Intake (ORI) | Visual observation | Updates from routine monitoring program-organization; Visual monitoring only-present bloom |
| Aug 8, 2024 | at Clifton Court Intake (ORI) | Visual observation | Updates from routine monitoring program-organization; Visual monitoring only-present bloom |
| Jul 3, 2024 | at Clifton Court Intake (ORI) | Visual observation | Updates from routine monitoring program-organization; Visual monitoring only-present bloom |
| Jun 18, 2024 | at Clifton Court Intake (ORI) | Visual observation | Updates from routine monitoring program-organization; Visual monitoring only-present bloom |
| May 3, 2024 | at Clifton Court Intake (ORI) | NA - refer to Report Details | Updates from routine monitoring program-organization; Visual monitoring only-absent bloom |
| Mar 8, 2024 | at Clifton Court Intake (ORI) | NA - refer to Report Details | Updates from routine monitoring program-organization; Visual monitoring only-absent bloom |
| Feb 12, 2024 | at Clifton Court Intake (ORI) | NA - refer to Report Details | Updates from routine monitoring program-organization; Visual monitoring only-absent bloom |
| Jan 22, 2024 | at Clifton Court Intake (ORI) | NA - refer to Report Details | Updates from routine monitoring program-organization; Visual monitoring only-absent bloom |
| Dec 8, 2023 | at Clifton Court Intake (ORI) | NA - refer to Report Details | Updates from routine monitoring program-organization; Visual monitoring only-absent bloom |
| Oct 11, 2023 | at Clifton Court Intake (ORI) | Visual observation | Updates from routine monitoring program-organization; Visual monitoring only-present bloom |
| Sep 8, 2023 | Old River downstream of Clifton Court Forebay Intake (WCI) | Visual observation | Updates from routine monitoring program-organization; Visual monitoring only-present bloom |
| Sep 8, 2023 | at Clifton Court Intake (ORI) | Visual observation | Updates from routine monitoring program-organization; Visual monitoring only-present bloom |
| Aug 7, 2023 | at Clifton Court Intake (ORI) | NA - refer to Report Details | Updates from routine monitoring program-organization; Visual monitoring only-absent bloom |
| Jun 29, 2023 | at Clifton Court Intake (ORI) | NA - refer to Report Details | Updates from routine monitoring program-organization; Visual monitoring only-absent bloom |
| Jun 29, 2023 | at Clifton Court Intake (ORI) | None | Updates from routine monitoring program-organization; Visual monitoring only-absent bloom |
| May 22, 2023 | at Clifton Court Intake (ORI) | None | Updates from routine monitoring program-organization |
| Apr 18, 2023 | at Clifton Court Intake (ORI) | None | Updates from routine monitoring program-organization |
| Mar 16, 2023 | Old River downstream of Clifton Court Forebay Intake (WCI) | None | Updates from routine monitoring program-organization |
| Mar 16, 2023 | at Clifton Court Intake (ORI) | None | Updates from routine monitoring program-organization |
| Jan 18, 2023 | Old River downstream of Clifton Court Forebay Intake (WCI) | None | Updates from routine monitoring program-organization |
| Jan 18, 2023 | at Clifton Court Intake (ORI) | None | Updates from routine monitoring program-organization |
| Jan 1, 2023 | at Clifton Court Intake (ORI) | None | Updates from routine monitoring program-organization |
| Dec 20, 2022 | at Clifton Court Intake (ORI) | None | visual monitoring based advisory |
| Dec 20, 2022 | at Clifton Court Intake (ORI) | None | visual monitoring based advisory |
| Nov 9, 2022 | at Clifton Court Intake (ORI) | Caution | Floating/planktonic bloom observed; Updates from routine monitoring program-organization; visual monitoring based advisory |
| Oct 12, 2022 | at Clifton Court Intake (ORI) | Caution | Floating/planktonic bloom observed; Updates from routine monitoring program-organization; visual monitoring based advisory |
| Sep 19, 2022 | at Clifton Court Intake (ORI) | Caution | Floating/planktonic bloom observed; Updates from routine monitoring program-organization; visual monitoring based advisory |
| Aug 10, 2022 | at Clifton Court Intake (ORI) | Caution | Floating/planktonic bloom observed; Updates from routine monitoring program-organization; visual monitoring based advisory |
| Jul 20, 2022 | at Clifton Court Intake (ORI) | Caution | Updates from routine monitoring program-organization |
| Jun 7, 2022 | at Clifton Court Intake (ORI) | Caution | Updates from routine monitoring program-organization |
| Apr 13, 2022 | at Clifton Court Intake (ORI) | None | Updates from routine monitoring program-organization |
| Jun 17, 2021 | at Kings Island | Caution | Advisory based on visual and toxins |
| Dec 4, 2018 | Old River at Confluence of West Canal, North of Clifton Court Forebay | None | |
| Dec 4, 2018 | Old River, near Clifton Court Forebay Intake | 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.