Eel River: toxic algae advisories
Eel River, Humboldt County. See all Humboldt County waters.
What the state's records say
Caution advisory, last posted Sep 16, 2026. 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: 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 Eel River
The state has an advisory on file for Eel River (Caution advisory), last posted Sep 16, 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 |
|---|---|
| near Fortuna | Algal mat alert sign, last posted Sep 16, 2026. No all-clear recorded. |
| Rio Dell | Algal mat alert sign, last posted Sep 14, 2026. No all-clear recorded. |
| Fernbridge | The state's latest record, from Nov 26, 2024, recommends no advisory. |
| near Fortuna | Caution advisory, last posted Sep 13, 2021. No all-clear recorded. |
| Eel River, Near Miranda, South of Maple Hills Rd. Bridg | Caution advisory, last posted Sep 18, 2017. No all-clear recorded. |
Advisory history
Every advisory record the state has published for 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 |
|---|---|---|---|
| Sep 16, 2026 | near Fortuna | Algal mat alert sign | Advisory based on visual and toxins; Updates from routine monitoring program-organization |
| Sep 14, 2026 | Rio Dell | Algal mat alert sign | Advisory based on visual and toxins; Suspected illness reported |
| Sep 3, 2026 | near Fortuna | Algal mat alert sign | Advisory based on visual and toxins; Updates from routine monitoring program-organization |
| Aug 14, 2026 | Rio Dell | Algal mat alert sign | Advisory based on visual and toxins; Suspected illness reported |
| Jul 24, 2026 | Rio Dell | Algal mat alert sign | Suspected illness reported; Under investigation |
| Jul 24, 2026 | Rio Dell | NA - refer to Report Details | Under investigation |
| Nov 26, 2024 | Fernbridge | None | De-posting advisory. |
| Sep 5, 2024 | Fernbridge | Algal mat alert sign | Suspected illness reported; Under investigation |
| Sep 13, 2021 | near Fortuna | Caution | visual monitoring based advisory |
| Sep 18, 2017 | Eel River, Near Miranda, South of Maple Hills Rd. Bridg | Caution |
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.