Biscar Reservior: toxic algae advisories
Biscar Reservior, Lassen County. See all Lassen County waters.
What the state's records say
The state's latest record, from Aug 28, 2026, recommends no advisory.
Last advisory on file: Sep 30, 2025.
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 Biscar Reservior
The state's latest record, from Aug 28, 2026, recommends no advisory. For Biscar Reservior, 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.
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 |
|---|---|
| near town Karlo and hwy 395 | The state's latest record, from Aug 28, 2026, recommends no advisory. |
Advisory history
Every advisory record the state has published for Biscar Reservior, 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, 2026 | near town Karlo and hwy 395 | None | Advisory based on visual and toxins |
| Aug 28, 2026 | near town Karlo and hwy 395 | None | Advisory based on visual and toxins |
| Jun 30, 2026 | near town Karlo and hwy 395 | None | Advisory based on visual and toxins |
| Sep 30, 2025 | near town Karlo and hwy 395 | Caution | Visual monitoring only-present bloom |
| Sep 27, 2024 | near town Karlo and hwy 395 | None | Advisory based on visual and toxins |
| Sep 10, 2024 | near town Karlo and hwy 395 | NA - refer to Report Details | Under investigation |
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.