Horseshoe Lake: toxic algae advisories
Horseshoe Lake, San Bernardino County. See all San Bernardino County waters.
What the state's records say
The state's latest record, from Sep 3, 2026, recommends no advisory.
Last advisory on file: Jun 11, 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 Horseshoe Lake
The state's latest record, from Sep 3, 2026, recommends no advisory. For Horseshoe 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.
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 |
|---|---|
| Mojave Narrows Regional Park | The state's latest record, from Sep 3, 2026, recommends no advisory. |
| Mojave Narrows Regional Park | The state's latest record, from Jun 23, 2023, recommends no advisory. |
| Mojave Narrows Regional Park | The state's latest record, from Jul 13, 2021, recommends no advisory. |
| Mojave Narrows Regional Park | The state's latest record, from Sep 4, 2020, recommends no advisory. |
Advisory history
Every advisory record the state has published for Horseshoe 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 |
|---|---|---|---|
| Sep 3, 2026 | Mojave Narrows Regional Park | None | Advisory based on visual and toxins |
| Jul 3, 2026 | Mojave Narrows Regional Park | None | Advisory based on visual and toxins |
| Jun 11, 2026 | Mojave Narrows Regional Park | Caution | Lake-wide advisory; Suspected bloom, investigation ongoing; Suspected illness reported; Under investigation |
| Jun 23, 2025 | Mojave Narrows Regional Park | None | Testing results below posting triggers |
| Jun 23, 2025 | Mojave Narrows Regional Park | None | Testing results below posting triggers |
| Aug 29, 2024 | Mojave Narrows Regional Park | None | Testing results below posting triggers |
| Aug 24, 2023 | Mojave Narrows Regional Park | None | Testing results below posting triggers; Updates from routine monitoring program-organization |
| Aug 24, 2023 | Mojave Narrows Regional Park | None | Testing results below posting triggers; Updates from routine monitoring program-organization |
| Jul 10, 2023 | Mojave Narrows Regional Park | None | Testing results below posting triggers; Updates from routine monitoring program-organization |
| Jun 23, 2023 | Mojave Narrows Regional Park | None | No cyano bloom w/testing; Updates from routine monitoring program-organization |
| May 26, 2023 | Mojave Narrows Regional Park | None | No cyano bloom w/testing; Updates from routine monitoring program-organization |
| Jul 13, 2021 | Mojave Narrows Regional Park | None | Testing results below posting triggers |
| Sep 4, 2020 | Mojave Narrows Regional Park | None | Rec general awareness |
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.