San Joaquin River: toxic algae advisories
San Joaquin River, Fresno County. See all Fresno County waters.
What the state's records say
Algal mat alert sign, last posted Aug 29, 2025. No all-clear recorded.
2 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: The state recorded an advisory of a type outside the Caution, Warning and Danger levels. Read the sign posted at the water.
Before you go, check the state's official algae page and any signs posted at the water.
Dogs at San Joaquin River
The state has an advisory on file for San Joaquin River (Algal mat alert sign), last posted Aug 29, 2025, 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 |
|---|---|
| SF Above Florence Lake (540SJRUPx) | Algal mat alert sign, last posted Aug 29, 2025. No all-clear recorded. |
| W Shields Ave, west of Fresno | Algal mat alert sign, last posted Jun 23, 2025. No all-clear recorded. |
Advisory history
Every advisory record the state has published for San Joaquin 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 |
|---|---|---|---|
| Aug 29, 2025 | SF Above Florence Lake (540SJRUPx) | Algal mat alert sign | Updates from routine monitoring program-organization |
| Jun 23, 2025 | W Shields Ave, west of Fresno | Algal mat alert sign | Advisory based on visual and toxins; Suspected illness reported |
| Jun 23, 2025 | W Shields Ave, west of Fresno | Algal mat alert sign | Advisory based on visual and toxins; Suspected illness reported |
| Jun 23, 2025 | W Shields Ave, west of Fresno | Algal mat alert sign | Advisory based on visual and toxins; Suspected illness reported |
| Jun 16, 2025 | W Shields Ave, west of Fresno | Caution | Suspected illness reported |
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.