Frenchman Lake: toxic algae advisories
Frenchman Lake, Plumas County. See all Plumas County waters.
What the state's records say
The state's latest record, from Nov 10, 2022, recommends no advisory.
Last advisory on file: Sep 9, 2022.
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 Frenchman Lake
The state's latest record, from Nov 10, 2022, recommends no advisory. For Frenchman 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 Frenchman 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 |
|---|---|
| Cove near Campground | The state's latest record, from Nov 10, 2022, recommends no advisory. |
| Frenchman Lake | Reports on file, with no advisory level the state has classified. |
Advisory history
Every advisory record the state has published for Frenchman 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 |
|---|---|---|---|
| Nov 10, 2022 | Cove near Campground | None | End date recorded: Nov 10, 2022. No cyano bloom w/testing |
| Sep 9, 2022 | Cove near Campground | Caution | Floating/planktonic bloom observed |
| May 11, 2020 | Frenchman Lake | NA - refer to Report Details |
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.