Whiskeytown Lake: toxic algae advisories
Whiskeytown Lake, Shasta County. See all Shasta County waters.
What the state's records say
The state's latest record, from Aug 28, 2023, recommends no advisory.
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 Whiskeytown Lake
The state's latest record, from Aug 28, 2023, recommends no advisory. For Whiskeytown 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)
Week ending Oct 17, 2026: about 12,000 cells/mL of cyanobacteria near the center of Whiskeytown Lake.
A satellite estimate from EPA CyAN for a 12.6 km² lake. It does not measure toxins and does not change the advisory status.
| Week ending | Estimate |
|---|---|
| Oct 17, 2026 | about 12,000 cells/mL |
| Aug 1, 2026 | about 7,200 cells/mL |
| Jul 18, 2026 | about 12,000 cells/mL |
| Dec 27, 2025 | about 29,000 cells/mL |
| Dec 13, 2025 | about 32,000 cells/mL |
| Feb 1, 2025 | about 150,000 cells/mL |
| Jan 25, 2025 | about 7,200 cells/mL |
| Dec 14, 2024 | about 15,000 cells/mL |
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 |
|---|---|
| Grizzly Gulch Rd. at intersection of Hwy 299W | The state's latest record, from Aug 28, 2023, recommends no advisory. |
| Mid Second Pond by hwy 299 | The state's latest record, from Aug 25, 2022, recommends no advisory. |
| Grizzly Gluch | The state's latest record, from Aug 25, 2022, recommends no advisory. |
| Grizzly Gulch at Whiskeytown Lake | The state's latest record, from Dec 10, 2019, recommends no advisory. |
| Whiskeytown Lake Pond 2 | The state's latest record, from Nov 6, 2019, recommends no advisory. |
| Grizzly Gulch arm of Whiskeytown Lake | The state's latest record, from Oct 25, 2018, recommends no advisory. |
Advisory history
Every advisory record the state has published for Whiskeytown 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 |
|---|---|---|---|
| Aug 28, 2023 | Grizzly Gulch Rd. at intersection of Hwy 299W | None | Testing results below posting triggers |
| Aug 25, 2022 | Mid Second Pond by hwy 299 | None | No cyano bloom w/testing; Updates from routine monitoring program-organization |
| Aug 25, 2022 | Grizzly Gluch | None | No cyano bloom w/testing |
| Aug 25, 2022 | Grizzly Gluch | None | No cyano bloom w/testing |
| Jul 26, 2022 | Mid Second Pond by hwy 299 | None | No cyano bloom w/testing |
| Jul 26, 2022 | Grizzly Gluch | None | No cyano bloom w/testing |
| May 27, 2022 | Grizzly Gluch | None | No cyano bloom w/testing |
| May 27, 2022 | Mid Second Pond by hwy 299 | None | No cyano bloom w/testing |
| Dec 10, 2019 | Grizzly Gulch at Whiskeytown Lake | None | |
| Nov 6, 2019 | Whiskeytown Lake Pond 2 | None | |
| Oct 25, 2018 | Grizzly Gulch arm of Whiskeytown Lake | None |
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.