Folsom Lake: toxic algae advisories
Folsom Lake, Placer County. See all Placer County waters.
What the state's records say
The state's latest record, from Jul 7, 2026, recommends no advisory.
Last advisory on file: Jun 29, 2026.
That reflects what the state knew on that date. It is not a finding that the water is safe now: blooms can return within days, and many are never reported.
Before you go, check the state's official algae page and any signs posted at the water.
Dogs at Folsom Lake
The state's latest record, from Jul 7, 2026, recommends no advisory. For Folsom Lake, that is not the same as an all-clear for today. Look at the water before your dog goes in: keep it out of green, blue-green or scummy water and away from mats on the shore.
Satellite estimate (not an advisory)
No satellite reading on file for Folsom Lake in recent weeks. Clouds, ice, or a lake shape the satellite's estimate near its center misses can cause this. It is a gap in the data, not a reading.
This is a satellite estimate from the U.S. EPA's Cyanobacteria Assessment Network, not an advisory. It estimates how much cyanobacteria is in the water near the lake's center, not whether toxins are present: a high number does not mean toxins, and a low one does not mean there are none. It covers lakes of about 1 square kilometer and larger, so small ponds, dog parks and most rivers are not covered, and clouds can hide a lake for weeks. It never changes the advisory status above.
Satellite estimates: U.S. EPA Cyanobacteria Assessment Network (CyAN), from Copernicus Sentinel-3 data. Provisional, research-level estimates; EPA does not endorse this site. Checked Oct 22, 2026.
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 |
|---|---|
| Granite Beach | The state's latest record, from Jul 7, 2026, recommends no advisory. |
| Granite Bay Beach | The state's latest record, from Jul 7, 2026, recommends no advisory. |
| Beals Point | The state's latest record, from Jul 6, 2026, recommends no advisory. |
| Beals Point | The state's latest record, from Jul 6, 2026, recommends no advisory. |
| Oak Beach | The state's latest record, from Jul 6, 2026, recommends no advisory. |
| Granite Bay Dike 1 | The state's latest record, from Jul 6, 2026, recommends no advisory. |
| Granite Bay Main North | The state's latest record, from Jul 6, 2026, recommends no advisory. |
| Granite Bay Main South | The state's latest record, from Jul 6, 2026, recommends no advisory. |
| Horseshoe Bar | The state's latest record, from Oct 11, 2022, recommends no advisory. |
| Rattlesnake Bar boat launch | The state's latest record, from May 25, 2021, recommends no advisory. |
| Beals Point Day use/beach | The state's latest record, from May 25, 2021, recommends no advisory. |
Advisory history
Every advisory record the state has published for Folsom Lake, 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 |
|---|---|---|---|
| Jul 7, 2026 | Granite Beach | None | Testing results below posting triggers |
| Jul 7, 2026 | Granite Bay Beach | None | Testing results below posting triggers |
| Jul 6, 2026 | Beals Point | None | Testing results below posting triggers |
| Jul 6, 2026 | Beals Point | None | Suspected illness reported |
| Jul 6, 2026 | Granite Beach | None | Suspected illness reported |
| Jul 6, 2026 | Granite Bay Beach | None | Suspected illness reported |
| Jul 6, 2026 | Beals Point | None | Testing results below posting triggers |
| Jul 6, 2026 | Oak Beach | None | Testing results below posting triggers |
| Jul 6, 2026 | Granite Bay Dike 1 | None | Testing results below posting triggers |
| Jul 6, 2026 | Granite Bay Main North | None | Testing results below posting triggers |
| Jul 6, 2026 | Granite Bay Main South | None | Testing results below posting triggers |
| Jul 1, 2026 | Beals Point | NA - refer to Report Details | Suspected illness reported |
| Jul 1, 2026 | Beals Point | Blank in the state's file | Suspected illness reported |
| Jun 29, 2026 | Granite Beach | Caution | Suspected illness reported |
| Jun 25, 2026 | Granite Bay Beach | Caution | Suspected illness reported |
| Oct 11, 2022 | Horseshoe Bar | None | End date recorded: Nov 11, 2022. Advisory based on visual and toxins |
| Oct 11, 2022 | Horseshoe Bar | None | Advisory based on visual and toxins |
| May 25, 2021 | Rattlesnake Bar boat launch | None | Testing results below posting triggers |
| May 25, 2021 | Beals Point Day use/beach | None | Testing results below posting triggers |
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.