South Fork Eel River: toxic algae advisories
South Fork Eel River, Humboldt County. See all Humboldt County waters.
What the state's records say
Caution advisory, last posted Oct 9, 2026. No all-clear recorded.
10 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 South Fork Eel River
The state has an advisory on file for South Fork Eel River (Caution advisory), last posted Oct 9, 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 |
|---|---|
| Richardson Grove State Park | Algal mat alert sign, last posted Oct 9, 2026. No all-clear recorded. |
| near Miranda (111SF2122) | Algal mat alert sign, last posted Oct 9, 2026. No all-clear recorded. |
| near confluence (111SF0011) | Algal mat alert sign, last posted Sep 16, 2026. No all-clear recorded. |
| Hooker Creek Road and Avenue of the Giants | Algal mat alert sign, last posted Aug 27, 2025. No all-clear recorded. |
| Redway Beach | Algal mat alert sign, last posted Aug 21, 2025. No all-clear recorded. |
| Cooks Valley | Algal mat alert sign, last posted Aug 20, 2025. No all-clear recorded. |
| Richardson Grove | The state's latest record, from Nov 26, 2024, recommends no advisory. |
| 9 Mile Monitoring Site | The state's latest record, from Nov 21, 2022, recommends no advisory. |
| 5 Mile Monitoring Site | The state's latest record, from Nov 21, 2022, recommends no advisory. |
| 2 Mile Monitoring Site | The state's latest record, from Nov 21, 2022, recommends no advisory. |
| 1 Mile Monitoring Site | The state's latest record, from Nov 21, 2022, recommends no advisory. |
| 1/2 Mile Monitoring Site | The state's latest record, from Nov 21, 2022, recommends no advisory. |
| 1/4 Mile Monitoring Site | The state's latest record, from Nov 21, 2022, recommends no advisory. |
| near Redway | The state's latest record, from Nov 21, 2022, recommends no advisory. |
| Richardson Grove State Park | Caution advisory, last posted Jul 30, 2021. No all-clear recorded. |
| Cooks Valley Campground | Caution advisory, last posted Jul 30, 2021. No all-clear recorded. |
| California Federation of Womens Clubs Grove | Caution advisory, last posted Jul 20, 2021. No all-clear recorded. |
| South Fork Eel River at Miranda | Caution advisory, last posted Oct 19, 2020. No all-clear recorded. |
Advisory history
Every advisory record the state has published for South Fork Eel 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 |
|---|---|---|---|
| Oct 9, 2026 | Richardson Grove State Park | Algal mat alert sign | Bottom/benthic bloom observed; Visual monitoring only-present bloom |
| Oct 9, 2026 | near Miranda (111SF2122) | Algal mat alert sign | Bottom/benthic bloom observed; Visual monitoring only-present bloom |
| Sep 24, 2026 | Richardson Grove State Park | Algal mat alert sign | Bottom/benthic bloom observed; Visual monitoring only-present bloom |
| Sep 24, 2026 | near Miranda (111SF2122) | Algal mat alert sign | Bottom/benthic bloom observed; Visual monitoring only-present bloom |
| Sep 16, 2026 | near confluence (111SF0011) | Algal mat alert sign | Advisory based on visual and toxins; Updates from routine monitoring program-organization |
| Sep 10, 2026 | Richardson Grove State Park | Algal mat alert sign | Bottom/benthic bloom observed; Visual monitoring only-present bloom |
| Sep 10, 2026 | near Miranda (111SF2122) | Algal mat alert sign | Bottom/benthic bloom observed; Visual monitoring only-present bloom |
| Sep 3, 2026 | near confluence (111SF0011) | Algal mat alert sign | Advisory based on visual and toxins; Updates from routine monitoring program-organization |
| Aug 19, 2026 | near confluence (111SF0011) | None | Updates from routine monitoring program-organization |
| Aug 27, 2025 | Hooker Creek Road and Avenue of the Giants | Algal mat alert sign | Under investigation |
| Aug 26, 2025 | near Miranda (111SF2122) | Algal mat alert sign | Advisory based on visual and toxins; Bottom/benthic bloom observed |
| Aug 26, 2025 | near Miranda (111SF2122) | Algal mat alert sign | Advisory based on visual and toxins; Bottom/benthic bloom observed |
| Aug 21, 2025 | Redway Beach | Algal mat alert sign | Advisory based on visual and toxins; Bottom/benthic bloom observed |
| Aug 21, 2025 | Redway Beach | Algal mat alert sign | Advisory based on visual and toxins; Bottom/benthic bloom observed |
| Aug 20, 2025 | Cooks Valley | Algal mat alert sign | Advisory based on visual and toxins; Bottom/benthic bloom observed |
| Aug 13, 2025 | Redway Beach | Algal mat alert sign | Suspected illness reported; Under investigation |
| Aug 13, 2025 | Redway Beach | Algal mat alert sign | Suspected illness reported; Under investigation |
| Aug 8, 2025 | Richardson Grove State Park | Algal mat alert sign | Bottom/benthic bloom observed; Under investigation; visual monitoring based advisory |
| Aug 8, 2025 | Richardson Grove State Park | Algal mat alert sign | Bottom/benthic bloom observed; Under investigation; visual monitoring based advisory |
| Nov 26, 2024 | Cooks Valley | None | De-posting advisory. |
| Nov 26, 2024 | Richardson Grove | None | De-posting advisory. |
| Aug 20, 2024 | Richardson Grove | Algal mat alert sign | Bottom/benthic bloom observed |
| Aug 20, 2024 | Cooks Valley | Algal mat alert sign | Bottom/benthic bloom observed |
| Dec 31, 2023 | Cooks Valley | None | End date recorded: Dec 31, 2023. De-posting advisory. |
| Dec 31, 2023 | Richardson Grove | None | End date recorded: Dec 31, 2023. De-posting advisory. |
| Dec 31, 2023 | near Miranda (111SF2122) | None | End date recorded: Dec 31, 2023. De-posting advisory. |
| Nov 3, 2023 | near Miranda (111SF2122) | Algal mat alert sign | Advisory based on visual and toxins; Alert-high concentration toxins; Bottom/benthic bloom observed |
| Oct 30, 2023 | near Miranda (111SF2122) | Algal mat alert sign | Advisory based on visual and toxins; Alert-high concentration toxins; Bottom/benthic bloom observed |
| Sep 8, 2023 | near Miranda (111SF2122) | Algal mat alert sign | Advisory based on visual and toxins; Alert-high concentration toxins; Bottom/benthic bloom observed |
| Aug 29, 2023 | Richardson Grove | Algal mat alert sign | Advisory based on visual and toxins; Bottom/benthic bloom observed |
| Aug 29, 2023 | Richardson Grove | Blank in the state's file | Advisory based on visual and toxins; Bottom/benthic bloom observed |
| Aug 28, 2023 | Cooks Valley | Algal mat alert sign | Alert-detached mats observed; Bottom/benthic bloom observed; Visual monitoring only-present bloom |
| Aug 28, 2023 | Cooks Valley | Algal mat alert sign | Alert-detached mats observed; Bottom/benthic bloom observed; Visual monitoring only-present bloom |
| Aug 18, 2023 | near Miranda (111SF2122) | Algal mat alert sign | Advisory based on visual and toxins; Alert-high concentration toxins; Bottom/benthic bloom observed |
| Nov 21, 2022 | 9 Mile Monitoring Site | None | End date recorded: Nov 21, 2022. Advisory based on visual and toxins; Updates from routine monitoring program-organization |
| Nov 21, 2022 | 5 Mile Monitoring Site | None | End date recorded: Nov 21, 2022. De-posting advisory. |
| Nov 21, 2022 | 2 Mile Monitoring Site | None | End date recorded: Nov 21, 2022. De-posting advisory. |
| Nov 21, 2022 | 1 Mile Monitoring Site | None | End date recorded: Nov 21, 2022. De-posting advisory. |
| Nov 21, 2022 | 1/2 Mile Monitoring Site | None | End date recorded: Nov 21, 2022. De-posting advisory. |
| Nov 21, 2022 | 1/4 Mile Monitoring Site | None | End date recorded: Nov 21, 2022. De-posting advisory. |
| Nov 21, 2022 | near Redway | None | End date recorded: Nov 21, 2022. De-posting advisory. |
| Nov 21, 2022 | near Redway | None | De-posting advisory. |
| Nov 21, 2022 | 1/4 Mile Monitoring Site | None | De-posting advisory. |
| Nov 21, 2022 | 1/2 Mile Monitoring Site | None | De-posting advisory. |
| Nov 21, 2022 | 1 Mile Monitoring Site | None | De-posting advisory. |
| Nov 21, 2022 | 2 Mile Monitoring Site | None | De-posting advisory. |
| Nov 21, 2022 | 5 Mile Monitoring Site | None | De-posting advisory. |
| Nov 21, 2022 | 9 Mile Monitoring Site | None | Advisory based on visual and toxins; Updates from routine monitoring program-organization |
| Oct 18, 2022 | 9 Mile Monitoring Site | Algal mat alert sign | Advisory based on visual and toxins; Updates from routine monitoring program-organization |
| Oct 18, 2022 | 5 Mile Monitoring Site | Algal mat alert sign | Advisory based on visual and toxins; Updates from routine monitoring program-organization |
| Oct 18, 2022 | 2 Mile Monitoring Site | Algal mat alert sign | Advisory based on visual and toxins; Updates from routine monitoring program-organization |
| Oct 18, 2022 | 1 Mile Monitoring Site | Algal mat alert sign | Advisory based on visual and toxins; Updates from routine monitoring program-organization |
| Oct 18, 2022 | 1/2 Mile Monitoring Site | Algal mat alert sign | Advisory based on visual and toxins; Updates from routine monitoring program-organization |
| Oct 18, 2022 | 1/4 Mile Monitoring Site | Algal mat alert sign | Advisory based on visual and toxins; Updates from routine monitoring program-organization |
| Oct 5, 2022 | 9 Mile Monitoring Site | Algal mat alert sign | Advisory based on visual and toxins; Updates from routine monitoring program-organization |
| Oct 5, 2022 | 5 Mile Monitoring Site | Algal mat alert sign | Advisory based on visual and toxins; Updates from routine monitoring program-organization |
| Oct 5, 2022 | 2 Mile Monitoring Site | Algal mat alert sign | Advisory based on visual and toxins; Updates from routine monitoring program-organization |
| Oct 5, 2022 | 1 Mile Monitoring Site | Algal mat alert sign | Advisory based on visual and toxins; Updates from routine monitoring program-organization |
| Oct 5, 2022 | 1/2 Mile Monitoring Site | Algal mat alert sign | Advisory based on visual and toxins; Updates from routine monitoring program-organization |
| Oct 5, 2022 | 1/4 Mile Monitoring Site | Algal mat alert sign | Advisory based on visual and toxins; Updates from routine monitoring program-organization |
| Sep 28, 2022 | 9 Mile Monitoring Site | Algal mat alert sign | Advisory based on visual and toxins; Updates from routine monitoring program-organization |
| Sep 28, 2022 | 9 Mile Monitoring Site | Blank in the state's file | Advisory based on visual and toxins; Updates from routine monitoring program-organization |
| Sep 28, 2022 | 5 Mile Monitoring Site | Algal mat alert sign | Advisory based on visual and toxins; Updates from routine monitoring program-organization |
| Sep 28, 2022 | 2 Mile Monitoring Site | Algal mat alert sign | Advisory based on visual and toxins; Updates from routine monitoring program-organization |
| Sep 28, 2022 | 1/2 Mile Monitoring Site | Algal mat alert sign | Advisory based on visual and toxins; Updates from routine monitoring program-organization |
| Sep 28, 2022 | 1 Mile Monitoring Site | Algal mat alert sign | Advisory based on visual and toxins; Updates from routine monitoring program-organization |
| Sep 28, 2022 | 1/2 Mile Monitoring Site | Blank in the state's file | Advisory based on visual and toxins; Updates from routine monitoring program-organization |
| Sep 28, 2022 | 1/4 Mile Monitoring Site | Algal mat alert sign | Advisory based on visual and toxins; Updates from routine monitoring program-organization |
| Aug 15, 2022 | near Redway | Algal mat alert sign | Bottom/benthic bloom observed; Under investigation; visual monitoring based advisory |
| Aug 15, 2022 | near Redway | Algal mat alert sign | Bottom/benthic bloom observed; Under investigation; visual monitoring based advisory |
| Aug 15, 2022 | near Redway | Algal mat alert sign | Bottom/benthic bloom observed; Under investigation; visual monitoring based advisory |
| Jul 30, 2021 | Richardson Grove State Park | Caution | visual monitoring based advisory |
| Jul 30, 2021 | Cooks Valley Campground | Caution | Advisory based on visual and toxins |
| Jul 20, 2021 | California Federation of Womens Clubs Grove | Caution | visual monitoring based advisory |
| Oct 19, 2020 | South Fork Eel River at Miranda | Caution | Advisory based on visual and toxins |
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.