Crowley Lake: toxic algae advisories
Crowley Lake, Mono County. See all Mono County waters.
What the state's records say
Danger advisory, last posted Sep 30, 2026. No all-clear recorded.
7 reported spots here have an advisory with no all-clear recorded.
Reporting is voluntary, so the state may not have recorded an end even if conditions changed. Check posted signs and the official map.
What this level asks: Toxins may be at levels that can seriously harm people and animals. Stay out of the water and keep children and pets away from the water and the shore.
Before you go, check the state's official algae page and any signs posted at the water.
Dogs at Crowley Lake
The state has an advisory on file for Crowley Lake (Danger advisory), last posted Sep 30, 2026, and no all-clear recorded. Keep your dog out of the water and away from scum on the shore until the state records an end.
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 |
|---|---|
| Hilton Creek Drainage | Danger advisory, last posted Sep 30, 2026. No all-clear recorded. |
| Marina | Danger advisory, last posted Sep 30, 2026. No all-clear recorded. |
| north end | The state's latest record, from Jun 24, 2021, recommends no advisory. |
| marina | The state's latest record, from Jun 24, 2021, recommends no advisory. |
| Crowley Lake Site 4 | Danger advisory, last posted Aug 26, 2020. No all-clear recorded. |
| Crowley Lake Site 2 | Danger advisory, last posted Aug 26, 2020. No all-clear recorded. |
| Crowley Lake, at Site 1 | Danger advisory, last posted Aug 26, 2020. No all-clear recorded. |
| Crowley Lake | Caution advisory, last posted Aug 26, 2020. No all-clear recorded. |
| Crowley Lake | Caution advisory, last posted Jul 20, 2018. No all-clear recorded. |
Advisory history
Every advisory record the state has published for Crowley 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 30, 2026 | Hilton Creek Drainage | Danger | Advisory based on visual and toxins |
| Sep 30, 2026 | Marina | Danger | Advisory based on visual and toxins |
| Aug 28, 2026 | Marina | Caution | Advisory based on visual and toxins |
| Aug 28, 2026 | Hilton Creek Drainage | Danger | Advisory based on visual and toxins |
| Aug 28, 2026 | Hilton Creek Drainage | Danger | Advisory based on visual and toxins |
| Jun 25, 2026 | Hilton Creek Drainage | Caution | Advisory based on visual and toxins |
| Jun 25, 2026 | Marina | Caution | Advisory based on visual and toxins |
| Oct 2, 2025 | Hilton Creek Drainage | Danger | Advisory based on visual and toxins |
| Oct 2, 2025 | Marina | Warning | Advisory based on visual and toxins |
| Aug 22, 2025 | Hilton Creek Drainage | Danger | Advisory based on visual and toxins |
| Aug 22, 2025 | Marina | Danger | Testing results below posting triggers |
| Jun 24, 2025 | Marina | Visual observation | Testing results below posting triggers |
| Jun 24, 2025 | Hilton Creek Drainage | Visual observation | Advisory based on visual and toxins |
| Jun 24, 2025 | Hilton Creek Drainage | None | Advisory based on visual and toxins |
| Jun 24, 2025 | Marina | None | Testing results below posting triggers |
| May 27, 2025 | Marina | None | Testing results below posting triggers |
| Oct 7, 2024 | Marina | Danger | Advisory based on visual and toxins |
| Oct 7, 2024 | Hilton Creek Drainage | Danger | Advisory based on visual and toxins |
| Aug 22, 2024 | Hilton Creek Drainage | Caution | Testing results below posting triggers |
| Aug 22, 2024 | Hilton Creek Drainage | None | Testing results below posting triggers |
| Aug 22, 2024 | Marina | Warning | Advisory based on visual and toxins |
| Jun 20, 2024 | Hilton Creek Drainage | None | Testing results below posting triggers |
| Jun 20, 2024 | Marina | Caution | Advisory based on visual and toxins |
| Sep 29, 2023 | Hilton Creek Drainage | Danger | Advisory based on visual and toxins; Lake-wide advisory |
| Sep 29, 2023 | Marina | Danger | Advisory based on visual and toxins; Lake-wide advisory |
| Sep 1, 2023 | Marina | Danger | Advisory based on visual and toxins; Lake-wide advisory |
| Sep 1, 2023 | Hilton Creek Drainage | Danger | Advisory based on visual and toxins; Lake-wide advisory |
| Aug 29, 2023 | Marina | Danger | Advisory based on visual and toxins; Lake-wide advisory |
| Aug 29, 2023 | Hilton Creek Drainage | Warning | Advisory based on visual and toxins |
| Aug 29, 2023 | Marina | Danger | Advisory based on visual and toxins |
| Aug 29, 2023 | Marina | Danger | Advisory based on visual and toxins |
| Aug 29, 2023 | Hilton Creek Drainage | Warning | Advisory based on visual and toxins |
| Jul 10, 2023 | Hilton Creek Drainage | Caution | Advisory based on visual and toxins; Lake-wide advisory; Suspected illness reported |
| Jun 27, 2023 | Marina | Caution | Lake-wide advisory; Suspected illness reported; Testing results below posting triggers; Under investigation |
| Jun 27, 2023 | Hilton Creek Drainage | Caution | Advisory based on visual and toxins; Lake-wide advisory; Suspected illness reported |
| Jun 27, 2023 | Marina | Caution | Lake-wide advisory; Suspected illness reported; Under investigation |
| Jun 13, 2023 | Hilton Creek Drainage | Caution | Advisory based on visual and toxins; Lake-wide advisory; Suspected illness reported |
| Jun 13, 2023 | Marina | Visual observation | Lake-wide advisory; Suspected bloom, investigation ongoing; visual monitoring based advisory; Visual monitoring only-present bloom |
| Jun 13, 2023 | Hilton Creek Drainage | Visual observation | Lake-wide advisory; Suspected bloom, investigation ongoing; Visual monitoring only-present bloom |
| Jun 13, 2023 | Marina | Visual observation | Lake-wide advisory; Suspected bloom, investigation ongoing; visual monitoring based advisory; Visual monitoring only-present bloom |
| Jun 13, 2023 | Marina | Visual observation | Lake-wide advisory; Suspected bloom, investigation ongoing; visual monitoring based advisory; Visual monitoring only-present bloom |
| Jun 13, 2023 | Hilton Creek Drainage | Visual observation | Lake-wide advisory; Suspected bloom, investigation ongoing; Visual monitoring only-present bloom |
| Jun 13, 2023 | Marina | Visual observation | Suspected bloom, investigation ongoing; visual monitoring based advisory; Visual monitoring only-present bloom |
| Jun 24, 2021 | north end | None | Testing results below posting triggers |
| Jun 24, 2021 | marina | None | Testing results below posting triggers |
| Aug 26, 2020 | Crowley Lake Site 4 | Danger | Advisory based on visual and toxins |
| Aug 26, 2020 | Crowley Lake Site 2 | Danger | Advisory based on visual and toxins |
| Aug 26, 2020 | Crowley Lake, at Site 1 | Danger | Advisory based on visual and toxins |
| Aug 26, 2020 | Crowley Lake | Caution | Lake-wide advisory |
| Jul 20, 2018 | Crowley Lake | Caution |
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.