Santa Margarita Lake: toxic algae advisories
Santa Margarita Lake, San Luis Obispo County. See all San Luis Obispo County waters.
What the state's records say
Caution advisory, last posted Dec 9, 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: 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 Santa Margarita Lake
The state has an advisory on file for Santa Margarita Lake (Caution advisory), last posted Dec 9, 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 |
|---|---|
| Santa Margarita Lake at Marina, main launch | The state's latest record, from Sep 4, 2026, recommends no advisory. |
| Santa Margarita Lake at Osprey Camp | General awareness, last posted Dec 9, 2022. No all-clear recorded. |
| Spot not described | Caution advisory, last posted Sep 2, 2021. No all-clear recorded. |
| Santa Margarita Lake (Salinas Reservoir) | The state's latest record, from May 25, 2021, recommends no advisory. |
| Santa Margarita Lake (Salinas Reservoir) | Caution advisory, last posted Nov 17, 2020. No all-clear recorded. |
Advisory history
Every advisory record the state has published for Santa Margarita 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 4, 2026 | Santa Margarita Lake at Marina, main launch | None | Rec general awareness; Updates from routine monitoring program-organization |
| Jun 25, 2026 | Santa Margarita Lake at Marina, main launch | General awareness | Rec general awareness; Updates from routine monitoring program-organization |
| May 22, 2026 | Santa Margarita Lake at Marina, main launch | General awareness | Rec general awareness; Updates from routine monitoring program-organization |
| Aug 28, 2025 | Santa Margarita Lake at Marina, main launch | None | Rec general awareness; Updates from routine monitoring program-organization |
| Jun 30, 2025 | Santa Margarita Lake at Marina, main launch | None | Rec general awareness; Updates from routine monitoring program-organization |
| May 15, 2025 | Santa Margarita Lake at Marina, main launch | None | Rec general awareness; Updates from routine monitoring program-organization |
| Aug 26, 2024 | Santa Margarita Lake at Marina, main launch | General awareness | Rec general awareness; Updates from routine monitoring program-organization |
| Jun 28, 2024 | Santa Margarita Lake at Marina, main launch | General awareness | Rec general awareness; Updates from routine monitoring program-organization |
| Jun 28, 2024 | Santa Margarita Lake at Marina, main launch | None | Rec general awareness; Updates from routine monitoring program-organization |
| May 21, 2024 | Santa Margarita Lake at Marina, main launch | None | Rec general awareness; Updates from routine monitoring program-organization |
| Aug 31, 2023 | Santa Margarita Lake at Marina, main launch | General awareness | Rec general awareness; Updates from routine monitoring program-organization |
| Jun 29, 2023 | Santa Margarita Lake at Marina, main launch | NA - refer to Report Details | Rec general awareness; Updates from routine monitoring program-organization |
| May 25, 2023 | Santa Margarita Lake at Marina, main launch | NA - refer to Report Details | Rec general awareness; Updates from routine monitoring program-organization |
| Dec 9, 2022 | Santa Margarita Lake at Osprey Camp | General awareness | Rec general awareness |
| Dec 9, 2022 | Santa Margarita Lake at Marina, main launch | General awareness | Rec general awareness |
| Nov 10, 2022 | Santa Margarita Lake at Marina, main launch | General awareness | Rec general awareness |
| Nov 10, 2022 | Santa Margarita Lake at Marina, main launch | General awareness | Rec general awareness |
| Oct 26, 2022 | Santa Margarita Lake at Marina, main launch | Caution | visual monitoring based advisory |
| Oct 19, 2022 | Santa Margarita Lake at Marina, main launch | General awareness | Posted general awareness |
| Oct 12, 2022 | Santa Margarita Lake at Marina, main launch | Caution | Lake-wide advisory |
| Sep 22, 2022 | Santa Margarita Lake at Marina, main launch | Caution | Lake-wide advisory |
| Sep 12, 2022 | Santa Margarita Lake at Marina, main launch | Caution | Suspected bloom, investigation ongoing |
| Sep 1, 2022 | Santa Margarita Lake at Marina, main launch | Caution | Suspected bloom, investigation ongoing |
| Sep 1, 2022 | Santa Margarita Lake at Marina, main launch | NA - refer to Report Details | Rec general awareness |
| Jun 30, 2022 | Santa Margarita Lake at Marina, main launch | None | Updates from routine monitoring program-organization |
| May 27, 2022 | Santa Margarita Lake at Marina, main launch | None | Updates from routine monitoring program-organization |
| Sep 2, 2021 | Spot not described | Caution | Advisory based on visual and toxins |
| May 25, 2021 | Santa Margarita Lake (Salinas Reservoir) | None | Testing results below posting triggers |
| Nov 17, 2020 | Santa Margarita Lake (Salinas Reservoir) | Caution | visual monitoring based 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.