Heenan Reservoir: toxic algae advisories
Heenan Reservoir, Alpine County. See all Alpine County waters.
What the state's records say
Caution advisory, last posted Oct 26, 2022. 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 Heenan Reservoir
The state has an advisory on file for Heenan Reservoir (Caution advisory), last posted Oct 26, 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.
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 |
|---|---|
| Dam | The state's latest record, from Oct 16, 2026, recommends no advisory. |
| Loading Zone | The state's latest record, from Oct 16, 2026, recommends no advisory. |
| Loading Zone | Caution advisory, last posted Oct 26, 2022. No all-clear recorded. |
| Heenan Reservoir | The state's latest record, from Jun 28, 2021, recommends no advisory. |
| Heenan Lake | The state's latest record, from Nov 3, 2020, recommends no advisory. |
Advisory history
Every advisory record the state has published for Heenan Reservoir, 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 16, 2026 | Dam | None | Advisory based on visual and toxins |
| Oct 16, 2026 | Loading Zone | None | Advisory based on visual and toxins |
| Aug 21, 2026 | Loading Zone | None | Advisory based on visual and toxins |
| Aug 21, 2026 | Dam | None | Advisory based on visual and toxins |
| Jun 19, 2026 | Dam | None | Advisory based on visual and toxins |
| Jun 19, 2026 | Loading Zone | None | Advisory based on visual and toxins |
| Oct 29, 2025 | Dam | None | Testing results below posting triggers |
| Oct 29, 2025 | Loading Zone | None | Testing results below posting triggers |
| Aug 25, 2025 | Dam | None | Testing results below posting triggers |
| Aug 25, 2025 | Loading Zone | None | Testing results below posting triggers |
| Aug 25, 2025 | Dam | None | Testing results below posting triggers |
| Jun 25, 2025 | Dam | None | Testing results below posting triggers |
| Jun 25, 2025 | Loading Zone | None | Testing results below posting triggers |
| Oct 7, 2024 | Dam | Caution | Updates from routine monitoring program-organization |
| Oct 7, 2024 | Loading Zone | Caution | Advisory based on visual and toxins; Updates from routine monitoring program-organization |
| Aug 29, 2024 | Dam | None | Updates from routine monitoring program-organization |
| Aug 29, 2024 | Loading Zone | Caution | Advisory based on visual and toxins; Updates from routine monitoring program-organization |
| Jun 27, 2024 | Loading Zone | None | Updates from routine monitoring program-organization |
| Jun 27, 2024 | Dam | None | Updates from routine monitoring program-organization |
| Aug 30, 2023 | Dam | None | Updates from routine monitoring program-organization |
| Aug 30, 2023 | Loading Zone | None | Updates from routine monitoring program-organization |
| Jul 6, 2023 | Loading Zone | None | Updates from routine monitoring program-organization |
| Oct 26, 2022 | Loading Zone | Caution | Advisory based on visual and toxins |
| Jun 23, 2022 | Loading Zone | None | No cyano bloom w/testing |
| May 20, 2022 | Loading Zone | None | No cyano bloom w/testing |
| Jun 28, 2021 | Heenan Reservoir | None | Testing results below posting triggers |
| Nov 3, 2020 | Heenan Lake | None | De-posting advisory. |
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.