Hensley Lake: toxic algae advisories
Hensley Lake, Madera County. See all Madera County waters.
What the state's records say
Caution advisory, last posted Aug 25, 2026. No all-clear recorded.
10 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: Algae that can make toxins may be present. Keep people, children and pets away from algae and scum, and do not let pets drink the water.
Before you go, check the state's official algae page and any signs posted at the water.
Dogs at Hensley Lake
The state has an advisory on file for Hensley Lake (Caution advisory), last posted Aug 25, 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.
Satellite estimate (not an advisory)
No satellite reading on file for Hensley Lake in recent weeks. Clouds, ice, or a lake shape the satellite's estimate near its center misses can cause this. It is a gap in the data, not a reading.
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 |
|---|---|
| at West Floating Dock (539MAD001) | Caution advisory, last posted Aug 25, 2026. No all-clear recorded. |
| at East Floating Dock (539MAD002) | Caution advisory, last posted Aug 25, 2026. No all-clear recorded. |
| at East Floating Dock | Caution advisory, last posted May 11, 2023. No all-clear recorded. |
| at East Floating Dock (539MAD002) | The state's latest record, from Dec 16, 2022, recommends no advisory. |
| at West Floating Dock (539MAD001) | The state's latest record, from Dec 16, 2022, recommends no advisory. |
| at East Floating Dock | Caution advisory, last posted Jun 23, 2021. No all-clear recorded. |
| western floating dock | Caution advisory, last posted Jun 23, 2021. No all-clear recorded. |
| Hensley Lake, at West Boat Ramp | Caution advisory, last posted Aug 27, 2020. No all-clear recorded. |
| Hensley Lake, East Boat Ramp 1 | Caution advisory, last posted Aug 27, 2020. No all-clear recorded. |
| Hensley Lake, at southern most boat ramp (west side) | Caution advisory, last posted Aug 27, 2020. No all-clear recorded. |
| Hensley Lake | Caution advisory, last posted Dec 10, 2019. No all-clear recorded. |
| Hensley Lake | Caution advisory, last posted Nov 18, 2018. No all-clear recorded. |
Advisory history
Every advisory record the state has published for Hensley 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 |
|---|---|---|---|
| Aug 25, 2026 | at West Floating Dock (539MAD001) | Caution | Advisory based on visual and toxins |
| Aug 25, 2026 | at East Floating Dock (539MAD002) | Caution | Advisory based on visual and toxins |
| Aug 18, 2026 | at East Floating Dock (539MAD002) | Caution | visual monitoring based advisory |
| Aug 18, 2026 | at West Floating Dock (539MAD001) | Caution | visual monitoring based advisory |
| Jun 22, 2026 | at East Floating Dock (539MAD002) | None | Testing results below posting triggers; Updates from routine monitoring program-organization |
| Jun 22, 2026 | at West Floating Dock (539MAD001) | None | Testing results below posting triggers; Updates from routine monitoring program-organization |
| Jun 22, 2026 | at East Floating Dock (539MAD002) | None | Testing results below posting triggers; Updates from routine monitoring program-organization |
| Jun 22, 2026 | at West Floating Dock (539MAD001) | None | Testing results below posting triggers; Updates from routine monitoring program-organization |
| Jun 22, 2026 | at East Floating Dock (539MAD002) | None | Testing results below posting triggers; Updates from routine monitoring program-organization |
| May 11, 2026 | at West Floating Dock (539MAD001) | None | Testing results below posting triggers; Updates from routine monitoring program-organization |
| May 11, 2026 | at East Floating Dock (539MAD002) | None | Testing results below posting triggers; Updates from routine monitoring program-organization |
| Oct 28, 2025 | at West Floating Dock (539MAD001) | None | Testing results below posting triggers; Updates from routine monitoring program-organization |
| Oct 28, 2025 | at East Floating Dock (539MAD002) | None | Testing results below posting triggers; Updates from routine monitoring program-organization |
| Aug 19, 2025 | at West Floating Dock (539MAD001) | Caution | Advisory based on visual and toxins; Updates from routine monitoring program-organization |
| Aug 19, 2025 | at East Floating Dock (539MAD002) | None | Testing results below posting triggers; Updates from routine monitoring program-organization |
| Jun 24, 2025 | at West Floating Dock (539MAD001) | None | Testing results below posting triggers; Updates from routine monitoring program-organization |
| Jun 24, 2025 | at East Floating Dock (539MAD002) | None | Testing results below posting triggers; Updates from routine monitoring program-organization |
| May 15, 2025 | at West Floating Dock (539MAD001) | Caution | Advisory based on visual and toxins; Updates from routine monitoring program-organization |
| May 15, 2025 | at East Floating Dock (539MAD002) | Caution | Advisory based on visual and toxins; Updates from routine monitoring program-organization |
| Aug 27, 2024 | at West Floating Dock (539MAD001) | General awareness | Testing results below posting triggers; Updates from routine monitoring program-organization |
| Aug 27, 2024 | at East Floating Dock (539MAD002) | General awareness | Testing results below posting triggers; Updates from routine monitoring program-organization |
| Jun 25, 2024 | at West Floating Dock (539MAD001) | Caution | Advisory due to historical data.; Updates from routine monitoring program-organization |
| Jun 25, 2024 | at East Floating Dock (539MAD002) | Caution | Advisory due to historical data.; Updates from routine monitoring program-organization |
| Jun 17, 2024 | at West Floating Dock (539MAD001) | Caution | Updates from routine monitoring program-organization; visual monitoring based advisory |
| Jun 17, 2024 | at East Floating Dock (539MAD002) | Caution | Updates from routine monitoring program-organization; visual monitoring based advisory |
| May 17, 2024 | at West Floating Dock (539MAD001) | Caution | Advisory based on visual and toxins; Lake-wide advisory; Updates from routine monitoring program-organization |
| Oct 26, 2023 | at West Floating Dock (539MAD001) | None | Testing results below posting triggers; Updates from routine monitoring program-organization |
| Oct 26, 2023 | at West Floating Dock (539MAD001) | None | Testing results below posting triggers; Updates from routine monitoring program-organization |
| Oct 26, 2023 | at East Floating Dock (539MAD002) | None | Testing results below posting triggers; Updates from routine monitoring program-organization |
| Aug 24, 2023 | at West Floating Dock (539MAD001) | Caution | Advisory based on visual and toxins; Lake-wide advisory |
| Aug 24, 2023 | at East Floating Dock (539MAD002) | Caution | Advisory based on visual and toxins; Lake-wide advisory |
| Jul 6, 2023 | at West Floating Dock (539MAD001) | None | Updates from routine monitoring program-organization |
| Jul 6, 2023 | at East Floating Dock (539MAD002) | None | Updates from routine monitoring program-organization |
| Jun 22, 2023 | at West Floating Dock (539MAD001) | Caution | Floating/planktonic bloom observed; Lake-wide advisory |
| Jun 22, 2023 | at East Floating Dock (539MAD002) | Caution | Alert-detached mats observed; Floating/planktonic bloom observed; Lake-wide advisory |
| May 23, 2023 | at East Floating Dock (539MAD002) | Caution | Floating/planktonic bloom observed; visual monitoring based advisory |
| May 23, 2023 | at West Floating Dock (539MAD001) | Caution | Floating/planktonic bloom observed; visual monitoring based advisory |
| May 11, 2023 | at West Floating Dock (539MAD001) | Caution | Floating/planktonic bloom observed; visual monitoring based advisory |
| May 11, 2023 | at East Floating Dock (539MAD002) | Caution | Floating/planktonic bloom observed; visual monitoring based advisory |
| May 11, 2023 | at East Floating Dock | Caution | Floating/planktonic bloom observed |
| Jan 1, 2023 | at East Floating Dock (539MAD002) | None | Updates from routine monitoring program-organization |
| Jan 1, 2023 | at West Floating Dock (539MAD001) | None | Updates from routine monitoring program-organization |
| Dec 16, 2022 | at East Floating Dock (539MAD002) | None | Updates from routine monitoring program-organization |
| Dec 16, 2022 | at West Floating Dock (539MAD001) | None | Updates from routine monitoring program-organization |
| Nov 16, 2022 | at West Floating Dock (539MAD001) | Warning | Advisory based on visual and toxins; Alert-high concentration toxins; Alert-scum observed; Floating/planktonic bloom observed; Updates from routine monitoring program-organization |
| Nov 16, 2022 | at East Floating Dock (539MAD002) | Warning | Advisory based on visual and toxins; Alert-high concentration toxins; Alert-scum observed; Updates from routine monitoring program-organization |
| Nov 14, 2022 | at East Floating Dock (539MAD002) | Warning | Advisory based on visual and toxins; Alert-high concentration toxins; Alert-scum observed; Updates from routine monitoring program-organization |
| Nov 14, 2022 | at West Floating Dock (539MAD001) | Danger | Advisory based on visual and toxins; Alert-high concentration toxins; Alert-scum observed; Floating/planktonic bloom observed; Updates from routine monitoring program-organization |
| Nov 9, 2022 | at West Floating Dock (539MAD001) | Danger | Advisory based on visual and toxins; Alert-high concentration toxins; Alert-scum observed; Floating/planktonic bloom observed; Updates from routine monitoring program-organization |
| Nov 9, 2022 | at West Floating Dock (539MAD001) | Warning | Advisory based on visual and toxins; Alert-high concentration toxins; Alert-scum observed; Floating/planktonic bloom observed; Updates from routine monitoring program-organization |
| Nov 9, 2022 | at East Floating Dock (539MAD002) | Warning | Advisory based on visual and toxins; Alert-high concentration toxins; Alert-scum observed; Updates from routine monitoring program-organization |
| Oct 27, 2022 | at West Floating Dock (539MAD001) | Warning | Advisory based on visual and toxins; Alert-high concentration toxins; Alert-scum observed; Floating/planktonic bloom observed; Updates from routine monitoring program-organization |
| Oct 27, 2022 | at East Floating Dock (539MAD002) | Warning | Advisory based on visual and toxins; Alert-high concentration toxins; Alert-scum observed; Updates from routine monitoring program-organization |
| Oct 10, 2022 | at East Floating Dock (539MAD002) | Danger | Advisory based on visual and toxins; Alert-high concentration toxins; Alert-scum observed; Updates from routine monitoring program-organization |
| Oct 10, 2022 | at West Floating Dock (539MAD001) | Danger | Advisory based on visual and toxins; Alert-high concentration toxins; Alert-scum observed; Floating/planktonic bloom observed; Updates from routine monitoring program-organization |
| Oct 10, 2022 | at East Floating Dock (539MAD002) | Warning | Advisory based on visual and toxins; Alert-high concentration toxins; Alert-scum observed; Updates from routine monitoring program-organization |
| Oct 5, 2022 | at East Floating Dock (539MAD002) | Danger | Advisory based on visual and toxins; Alert-high concentration toxins; Alert-scum observed; Updates from routine monitoring program-organization |
| Oct 5, 2022 | at West Floating Dock (539MAD001) | Warning | Advisory based on visual and toxins; Alert-high concentration toxins; Floating/planktonic bloom observed; Updates from routine monitoring program-organization |
| Oct 5, 2022 | at West Floating Dock (539MAD001) | Danger | Advisory based on visual and toxins; Alert-high concentration toxins; Floating/planktonic bloom observed; Updates from routine monitoring program-organization |
| Sep 27, 2022 | at West Floating Dock (539MAD001) | Warning | Advisory based on visual and toxins; Alert-high concentration toxins; Floating/planktonic bloom observed; Updates from routine monitoring program-organization |
| Sep 27, 2022 | at East Floating Dock (539MAD002) | Warning | Advisory based on visual and toxins; Alert-high concentration toxins; Alert-scum observed; Updates from routine monitoring program-organization |
| Sep 2, 2022 | at West Floating Dock (539MAD001) | Warning | Advisory based on visual and toxins; Alert-high concentration toxins; Floating/planktonic bloom observed; Updates from routine monitoring program-organization |
| Sep 2, 2022 | at East Floating Dock (539MAD002) | Danger | Advisory based on visual and toxins; Alert-high concentration toxins; Alert-scum observed; Updates from routine monitoring program-organization |
| Aug 30, 2022 | at East Floating Dock (539MAD002) | Danger | Advisory based on visual and toxins; Alert-high concentration toxins; Alert-scum observed; Updates from routine monitoring program-organization |
| Aug 25, 2022 | at West Floating Dock (539MAD001) | Warning | Advisory based on visual and toxins; Alert-high concentration toxins; Floating/planktonic bloom observed; Updates from routine monitoring program-organization |
| Aug 25, 2022 | at West Floating Dock (539MAD001) | Caution | Advisory based on visual and toxins; Updates from routine monitoring program-organization |
| Aug 25, 2022 | at East Floating Dock (539MAD002) | Caution | Advisory based on visual and toxins; Updates from routine monitoring program-organization |
| Aug 18, 2022 | at West Floating Dock (539MAD001) | Caution | Advisory based on visual and toxins |
| Aug 18, 2022 | at East Floating Dock (539MAD002) | Caution | Advisory based on visual and toxins |
| Aug 5, 2022 | at West Floating Dock (539MAD001) | Caution | Advisory based on visual and toxins |
| Aug 5, 2022 | at East Floating Dock (539MAD002) | Caution | Advisory based on visual and toxins |
| Aug 3, 2022 | at West Floating Dock (539MAD001) | Caution | Advisory based on visual and toxins |
| Aug 3, 2022 | at East Floating Dock (539MAD002) | Caution | Advisory based on visual and toxins |
| Jul 21, 2022 | at West Floating Dock (539MAD001) | Caution | Advisory based on visual and toxins |
| Jul 21, 2022 | at East Floating Dock (539MAD002) | Caution | Advisory based on visual and toxins |
| Jul 7, 2022 | at West Floating Dock (539MAD001) | Caution | Advisory based on visual and toxins |
| Jul 7, 2022 | at East Floating Dock (539MAD002) | Caution | Advisory based on visual and toxins |
| Jun 22, 2022 | at West Floating Dock (539MAD001) | Caution | Advisory based on visual and toxins |
| Jun 22, 2022 | at East Floating Dock (539MAD002) | Caution | Advisory based on visual and toxins |
| Jun 22, 2022 | at West Floating Dock (539MAD001) | None | Advisory based on visual and toxins |
| Jun 22, 2022 | at East Floating Dock (539MAD002) | None | Advisory based on visual and toxins |
| May 31, 2022 | at West Floating Dock (539MAD001) | Danger | Advisory based on visual and toxins |
| May 31, 2022 | at East Floating Dock (539MAD002) | Warning | Advisory based on visual and toxins |
| May 26, 2022 | at West Floating Dock (539MAD001) | Danger | Advisory based on visual and toxins |
| May 26, 2022 | at East Floating Dock (539MAD002) | Warning | Advisory based on visual and toxins |
| Apr 1, 2022 | at West Floating Dock (539MAD001) | Danger | Advisory based on visual and toxins |
| Apr 1, 2022 | at East Floating Dock (539MAD002) | Warning | Advisory based on visual and toxins |
| Jun 23, 2021 | at East Floating Dock | Caution | Advisory based on visual and toxins |
| Jun 23, 2021 | western floating dock | Caution | Advisory based on visual and toxins |
| Aug 27, 2020 | Hensley Lake, at West Boat Ramp | Caution | Advisory based on visual and toxins |
| Aug 27, 2020 | Hensley Lake, East Boat Ramp 1 | Caution | Advisory based on visual and toxins |
| Aug 27, 2020 | Hensley Lake, at southern most boat ramp (west side) | Caution | Advisory based on visual and toxins |
| Dec 10, 2019 | Hensley Lake | Caution | |
| Nov 18, 2018 | Hensley 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.