Tule Lake Wildlife Refuge: toxic algae advisories
Tule Lake Wildlife Refuge, Siskiyou County. See all Siskiyou County waters.
What the state's records say
Danger advisory, last posted Sep 24, 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 Tule Lake Wildlife Refuge
The state has an advisory on file for Tule Lake Wildlife Refuge (Danger advisory), last posted Sep 24, 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 |
|---|---|
| Donut Hole area (TLNWR 1a) | Danger advisory, last posted Sep 24, 2026. No all-clear recorded. |
| Sump 1A boat ramp | Caution advisory, last posted May 20, 2026. No all-clear recorded. |
| Sump 1B northwest corner | The state's latest record, from Jul 28, 2025, recommends no advisory. |
| Sump 1A near levee | Caution advisory, last posted Jul 24, 2025. No all-clear recorded. |
| Sump 1A southwest shore | The state's latest record, from Apr 27, 2023, recommends no advisory. |
| Sump 1A near levee | The state's latest record, from Jan 4, 2023, recommends no advisory. |
| Sump 1B northwest corner | The state's latest record, from Jan 4, 2023, recommends no advisory. |
| Sump 1A southwest shore. | The state's latest record, from Jan 4, 2023, recommends no advisory. |
| Sump 1A boat ramp | The state's latest record, from Jan 4, 2023, recommends no advisory. |
| Sump 1B northwest corner | Caution advisory, last posted Jul 14, 2021. No all-clear recorded. |
| Sump 1A southwest shore | Caution advisory, last posted Jul 14, 2021. No all-clear recorded. |
| Sump 1A near levee | Caution advisory, last posted Jul 14, 2021. No all-clear recorded. |
| Sump 1A boat ramp | Caution advisory, last posted Jul 14, 2021. No all-clear recorded. |
Advisory history
Every advisory record the state has published for Tule Lake Wildlife Refuge, 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 24, 2026 | Donut Hole area (TLNWR 1a) | Danger | Updates from routine monitoring program-organization |
| Aug 12, 2026 | Donut Hole area (TLNWR 1a) | Warning | Updates from routine monitoring program-organization |
| Jul 14, 2026 | Donut Hole area (TLNWR 1a) | Caution | Updates from routine monitoring program-organization |
| Jun 10, 2026 | Donut Hole area (TLNWR 1a) | Caution | Updates from routine monitoring program-organization |
| May 20, 2026 | Sump 1A boat ramp | Caution | Advisory based on visual and toxins |
| May 12, 2026 | Sump 1A boat ramp | Caution | Suspected bloom, investigation ongoing; Under investigation; Visual monitoring only-present bloom |
| Sep 29, 2025 | Donut Hole area (TLNWR 1a) | Caution | Floating/planktonic bloom observed; Updates from routine monitoring program-organization |
| Jul 29, 2025 | Donut Hole area (TLNWR 1a) | Caution | Floating/planktonic bloom observed; Updates from routine monitoring program-organization |
| Jul 28, 2025 | Sump 1B northwest corner | None | Floating/planktonic bloom observed; Updates from routine monitoring program-organization; visual monitoring based advisory |
| Jul 28, 2025 | Sump 1B northwest corner | None | Floating/planktonic bloom observed; Updates from routine monitoring program-organization; visual monitoring based advisory |
| Jul 24, 2025 | Sump 1A near levee | Caution | Advisory based on visual and toxins; Updates from routine monitoring program-organization |
| Jul 1, 2025 | Donut Hole area (TLNWR 1a) | None | Testing results below posting triggers; Updates from routine monitoring program-organization |
| Jun 9, 2025 | Donut Hole area (TLNWR 1a) | Caution | Updates from routine monitoring program-organization |
| Apr 27, 2023 | Sump 1B northwest corner | None | No cyano bloom w/testing; Updates from routine monitoring program-organization |
| Apr 27, 2023 | Sump 1A southwest shore | None | De-watered site |
| Apr 27, 2023 | Sump 1A boat ramp | None | De-watered site |
| Apr 27, 2023 | Sump 1A near levee | None | No cyano bloom w/testing; Updates from routine monitoring program-organization |
| Apr 27, 2023 | Sump 1B northwest corner | None | De-watered site |
| Mar 27, 2023 | Sump 1A near levee | None | No cyano bloom w/testing; Updates from routine monitoring program-organization |
| Mar 13, 2023 | Sump 1B northwest corner | None | De-watered site |
| Mar 13, 2023 | Sump 1A southwest shore | None | De-watered site |
| Mar 13, 2023 | Sump 1A boat ramp | None | De-watered site |
| Mar 13, 2023 | Sump 1A near levee | None | No cyano bloom w/testing; Updates from routine monitoring program-organization |
| Mar 6, 2023 | Sump 1B northwest corner | None | De-watered site |
| Mar 6, 2023 | Sump 1A southwest shore | None | De-watered site |
| Mar 6, 2023 | Sump 1A boat ramp | None | De-watered site |
| Mar 6, 2023 | Sump 1A near levee | None | No cyano bloom w/testing; Updates from routine monitoring program-organization |
| Jan 23, 2023 | Sump 1B northwest corner | None | De-watered site |
| Jan 23, 2023 | Sump 1A southwest shore | None | De-watered site |
| Jan 23, 2023 | Sump 1A boat ramp | None | De-watered site |
| Jan 23, 2023 | Sump 1A near levee | None | No cyano bloom w/testing; Updates from routine monitoring program-organization |
| Jan 4, 2023 | Sump 1A near levee | None | End date recorded: Dec 12, 2022. Testing results below posting triggers |
| Jan 4, 2023 | Sump 1B northwest corner | None | End date recorded: Dec 12, 2022. De-watered site |
| Jan 4, 2023 | Sump 1A southwest shore. | None | End date recorded: Dec 12, 2022. De-watered site |
| Jan 4, 2023 | Sump 1A boat ramp | None | End date recorded: Dec 12, 2022. De-watered site |
| Dec 30, 2022 | Sump 1A boat ramp | None | End date recorded: Dec 12, 2022. De-watered site |
| Dec 30, 2022 | Sump 1A southwest shore. | None | End date recorded: Dec 12, 2022. De-watered site |
| Dec 30, 2022 | Sump 1B northwest corner | None | End date recorded: Dec 12, 2022. De-watered site |
| Dec 30, 2022 | Sump 1A near levee | None | End date recorded: Dec 12, 2022. Testing results below posting triggers |
| Dec 8, 2022 | Sump 1A near levee | None | End date recorded: Dec 8, 2022. Testing results below posting triggers |
| Dec 8, 2022 | Sump 1A near levee | None | Testing results below posting triggers |
| Dec 8, 2022 | Sump 1A near levee | None | Testing results below posting triggers |
| Nov 15, 2022 | Sump 1A near levee | None | Testing results below posting triggers |
| Nov 2, 2022 | Sump 1A boat ramp | None | End date recorded: Nov 2, 2022. De-watered site |
| Nov 2, 2022 | Sump 1A southwest shore. | None | End date recorded: Nov 2, 2022. De-watered site |
| Nov 2, 2022 | Sump 1B northwest corner | None | De-watered site |
| Nov 2, 2022 | Sump 1A southwest shore. | None | De-watered site |
| Nov 2, 2022 | Sump 1A boat ramp | None | De-watered site |
| Nov 2, 2022 | Sump 1A near levee | None | De-watered site |
| Oct 31, 2022 | Sump 1B northwest corner | None | De-watered site |
| Oct 31, 2022 | Sump 1A southwest shore. | None | De-watered site |
| Oct 31, 2022 | Sump 1A boat ramp | None | De-watered site |
| Oct 31, 2022 | Sump 1A near levee | None | De-watered site |
| Oct 3, 2022 | Sump 1A near levee | None | De-watered site |
| Oct 3, 2022 | Sump 1A boat ramp | None | De-watered site |
| Oct 3, 2022 | Sump 1A southwest shore. | None | De-watered site |
| Oct 3, 2022 | Sump 1B northwest corner | None | De-watered site |
| Aug 24, 2022 | Sump 1B northwest corner | Caution | Alert-high concentration toxins; Updates from routine monitoring program-organization |
| Aug 24, 2022 | Sump 1A southwest shore. | None | De-watered site |
| Aug 24, 2022 | Sump 1A boat ramp | None | De-watered site |
| Aug 24, 2022 | Sump 1A near levee | None | De-watered site |
| Aug 24, 2022 | Sump 1B northwest corner | Caution | Alert-high concentration toxins; Updates from routine monitoring program-organization |
| Aug 24, 2022 | Sump 1A southwest shore. | None | De-watered site |
| Aug 24, 2022 | Sump 1A boat ramp | None | De-watered site |
| Aug 24, 2022 | Sump 1A near levee | None | De-watered site |
| Jul 28, 2022 | Sump 1B northwest corner | Caution | Updates from routine monitoring program-organization |
| Jul 28, 2022 | Sump 1A southwest shore. | None | De-watered site |
| Jul 28, 2022 | Sump 1A boat ramp | None | De-watered site |
| Jul 28, 2022 | Sump 1A near levee | None | De-watered site |
| Jul 13, 2022 | Sump 1B northwest corner | Caution | Updates from routine monitoring program-organization |
| Jul 13, 2022 | Sump 1A southwest shore. | None | De-watered site |
| Jul 13, 2022 | Sump 1A boat ramp | None | De-watered site |
| Jul 13, 2022 | Sump 1A near levee | None | De-watered site |
| Jun 23, 2022 | Sump 1B northwest corner | None | Updates from routine monitoring program-organization |
| Jun 23, 2022 | Sump 1A southwest shore. | None | De-watered site |
| Jun 23, 2022 | Sump 1A boat ramp | None | De-watered site |
| Jun 23, 2022 | Sump 1A near levee | None | De-watered site |
| May 26, 2022 | Sump 1B northwest corner | None | Updates from routine monitoring program-organization |
| May 26, 2022 | Sump 1A southwest shore. | None | De-watered site |
| May 26, 2022 | Sump 1A boat ramp | None | De-watered site |
| May 26, 2022 | Sump 1A near levee | None | De-watered site |
| May 18, 2022 | Sump 1A southwest shore. | None | De-watered site |
| May 18, 2022 | Sump 1A boat ramp | None | De-watered site |
| May 18, 2022 | Sump 1A near levee | None | De-watered site |
| May 18, 2022 | Sump 1B northwest corner | None | Updates from routine monitoring program-organization |
| Apr 27, 2022 | Sump 1A near levee | None | De-watered site |
| Apr 27, 2022 | Sump 1A boat ramp | None | De-watered site |
| Apr 27, 2022 | Sump 1A southwest shore. | None | De-watered site |
| Apr 27, 2022 | Sump 1B northwest corner | None | De-posting advisory. |
| Mar 22, 2022 | Sump 1B northwest corner | Caution | De-watered site |
| Mar 22, 2022 | Sump 1A southwest shore. | None | De-watered site |
| Mar 22, 2022 | Sump 1A near levee | None | De-watered site |
| Mar 22, 2022 | Sump 1A boat ramp | None | De-watered site |
| Jul 14, 2021 | Sump 1B northwest corner | Caution | Advisory based on visual and toxins |
| Jul 14, 2021 | Sump 1A southwest shore | Caution | Advisory based on visual and toxins |
| Jul 14, 2021 | Sump 1A near levee | Caution | Advisory based on visual and toxins |
| Jul 14, 2021 | Sump 1A boat ramp | Caution | Advisory based on visual and toxins |
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.