Stampede Reservoir: toxic algae advisories
Stampede Reservoir, Sierra County. See all Sierra County waters.
What the state's records say
The state's latest record, from Oct 7, 2026, 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 Stampede Reservoir
The state's latest record, from Oct 7, 2026, recommends no advisory. For Stampede Reservoir, 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 8,300 cells/mL of cyanobacteria near the center of Stampede Reservoir.
A satellite estimate from EPA CyAN for a 13.1 km² lake. It does not measure toxins and does not change the advisory status.
| Week ending | Estimate |
|---|---|
| Oct 17, 2026 | about 8,300 cells/mL |
| Jun 6, 2026 | about 9,600 cells/mL |
| Feb 7, 2026 | about 17,000 cells/mL |
| Dec 14, 2024 | about 19,000 cells/mL |
| Dec 7, 2024 | about 7,700 cells/mL |
| Oct 14, 2023 | about 22,000 cells/mL |
| Sep 30, 2023 | about 7,700 cells/mL |
| Sep 9, 2023 | about 53,000 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 |
|---|---|
| Boat Launch Area | The state's latest record, from Oct 7, 2026, recommends no advisory. |
| Boat Launch Access Road | The state's latest record, from Aug 17, 2022, recommends no advisory. |
Advisory history
Every advisory record the state has published for Stampede Reservoir, 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 |
|---|---|---|---|
| Oct 7, 2026 | Boat Launch Area | None | Advisory based on visual and toxins; Confirmed no bloom |
| Sep 3, 2026 | Boat Launch Area | None | Advisory based on visual and toxins; Confirmed no bloom |
| Jun 24, 2026 | Boat Launch Area | None | Advisory based on visual and toxins; Confirmed no bloom |
| Oct 2, 2025 | Boat Launch Area | None | Advisory based on visual and toxins; Confirmed no bloom |
| Aug 22, 2025 | Boat Launch Area | None | Advisory based on visual and toxins |
| Aug 22, 2025 | Boat Launch Area | None | Advisory based on visual and toxins |
| Jun 26, 2025 | Boat Launch Area | None | Advisory based on visual and toxins |
| Oct 9, 2024 | Boat Launch Area | None | Advisory based on visual and toxins |
| Aug 28, 2024 | Boat Launch Area | None | Updates from routine monitoring program-organization |
| Jun 26, 2024 | Boat Launch Area | None | Updates from routine monitoring program-organization |
| Oct 19, 2023 | Boat Launch Area | None | Updates from routine monitoring program-organization |
| Aug 28, 2023 | Boat Launch Area | None | Updates from routine monitoring program-organization |
| Jul 5, 2023 | Boat Launch Area | None | Updates from routine monitoring program-organization |
| Aug 17, 2022 | Boat Launch Access Road | None | visual monitoring based advisory |
| Jun 23, 2022 | Boat Launch Access Road | None | No cyano, other algae present. |
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.