Lake Crowley: toxic algae advisories
Lake Crowley, Mono County. See all Mono County waters.
What the state's records say
Danger advisory, last posted Oct 19, 2022. No all-clear recorded.
3 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 Lake Crowley
The state has an advisory on file for Lake Crowley (Danger advisory), last posted Oct 19, 2022, 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.
Satellite estimate (not an advisory)
Week ending Oct 17, 2026: about 640,000 cells/mL of cyanobacteria near the center of Lake Crowley.
A satellite estimate from EPA CyAN for a 16.2 km² lake. It does not measure toxins and does not change the advisory status.
| Week ending | Estimate |
|---|---|
| Oct 17, 2026 | about 640,000 cells/mL |
| Oct 10, 2026 | about 600,000 cells/mL |
| Oct 3, 2026 | about 670,000 cells/mL |
| Sep 26, 2026 | about 730,000 cells/mL |
| Sep 19, 2026 | about 820,000 cells/mL |
| Sep 12, 2026 | about 890,000 cells/mL |
| Sep 5, 2026 | about 360,000 cells/mL |
| Aug 29, 2026 | about 180,000 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 |
|---|---|
| Marina | Danger advisory, last posted Oct 19, 2022. No all-clear recorded. |
| Hilton Creek Drainage | Danger advisory, last posted Oct 19, 2022. No all-clear recorded. |
| Crowley | Caution advisory, last posted Jul 21, 2022. No all-clear recorded. |
Advisory history
Every advisory record the state has published for Lake Crowley, 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 19, 2022 | Marina | Danger | Advisory based on visual and toxins |
| Oct 19, 2022 | Hilton Creek Drainage | Danger | visual monitoring based advisory |
| Sep 2, 2022 | Marina | Danger | Advisory based on visual and toxins |
| Sep 2, 2022 | Marina | Danger | Advisory based on visual and toxins |
| Aug 30, 2022 | Hilton Creek Drainage | Caution | visual monitoring based advisory |
| Aug 30, 2022 | Hilton Creek Drainage | Caution | visual monitoring based advisory |
| Jul 29, 2022 | Marina | Danger | Advisory based on visual and toxins |
| Jul 28, 2022 | Hilton Creek Drainage | Caution | Advisory based on visual and toxins |
| Jul 28, 2022 | Marina | None | Testing results below posting triggers |
| Jul 21, 2022 | Crowley | Caution | visual monitoring based advisory |
| Jul 15, 2022 | Hilton Creek Drainage | Caution | visual monitoring based advisory |
| Jul 1, 2022 | Hilton Creek Drainage | None | Testing results below posting triggers |
| Jul 1, 2022 | Marina | None | Testing results below posting triggers |
| May 11, 2022 | Hilton Creek Drainage | None | No cyano bloom w/testing |
| May 11, 2022 | Marina | None | No cyano bloom w/testing |
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.