Lake Merced: toxic algae advisories
Lake Merced, San Francisco County. See all San Francisco County waters.
What the state's records say
Danger advisory, last posted Jun 27, 2024. 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: 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 Merced
The state has an advisory on file for Lake Merced (Danger advisory), last posted Jun 27, 2024, 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 |
|---|---|
| South end of lake near Daly City | Reports on file, with no advisory level the state has classified. |
| Lake Merced North ("SS") | Warning advisory, last posted Jun 27, 2024. No all-clear recorded. |
| Lake Merced East ("E") | Warning advisory, last posted Jun 27, 2024. No all-clear recorded. |
| Lake Merced South ("CB") | Warning advisory, last posted Jun 27, 2024. No all-clear recorded. |
| Lake Merced South ("BD") | Danger advisory, last posted Dec 6, 2022. No all-clear recorded. |
| Lake Merced South ("S") | Danger advisory, last posted Dec 6, 2022. No all-clear recorded. |
| Lake Merced South ("R") | Danger advisory, last posted Dec 6, 2022. No all-clear recorded. |
| Lake Merced North ("NS") | Danger advisory, last posted Dec 6, 2022. No all-clear recorded. |
| Lake Merced East "E" | Danger advisory, last posted Dec 6, 2022. No all-clear recorded. |
| Lake Merced, "north" portion of lake | Danger advisory, last posted Jul 9, 2021. No all-clear recorded. |
| Lake Merced, "east" portion of lake | Danger advisory, last posted Jul 9, 2021. No all-clear recorded. |
Advisory history
Every advisory record the state has published for Lake Merced, 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 1, 2026 | South end of lake near Daly City | NA - refer to Report Details | Suspected bloom, investigation ongoing |
| Sep 1, 2026 | South end of lake near Daly City | NA - refer to Report Details | Under investigation |
| Jun 27, 2024 | Lake Merced North ("SS") | Warning | Updates from routine monitoring program-organization |
| Jun 27, 2024 | Lake Merced East ("E") | Warning | Updates from routine monitoring program-organization |
| Jun 27, 2024 | Lake Merced South ("CB") | Warning | Updates from routine monitoring program-organization |
| Dec 6, 2022 | Lake Merced South ("CB") | Danger | Updates from routine monitoring program-organization |
| Dec 6, 2022 | Lake Merced South ("BD") | Danger | |
| Dec 6, 2022 | Lake Merced South ("S") | Danger | Updates from routine monitoring program-organization |
| Dec 6, 2022 | Lake Merced South ("R") | Danger | |
| Dec 6, 2022 | Lake Merced East ("E") | Danger | Updates from routine monitoring program-organization |
| Dec 6, 2022 | Lake Merced North ("SS") | Blank in the state's file | Updates from routine monitoring program-organization |
| Dec 6, 2022 | Lake Merced North ("NS") | Danger | Updates from routine monitoring program-organization |
| Dec 6, 2022 | Lake Merced East "E" | Danger | Updates from routine monitoring program-organization |
| Dec 6, 2022 | Lake Merced East "E" | Danger | Updates from routine monitoring program-organization |
| Dec 6, 2022 | Lake Merced East "E" | Danger | Updates from routine monitoring program-organization |
| Dec 6, 2022 | Lake Merced East "E" | Danger | Updates from routine monitoring program-organization |
| Dec 6, 2022 | Lake Merced East "E" | Danger | Updates from routine monitoring program-organization |
| Dec 6, 2022 | Lake Merced East "E" | Danger | Updates from routine monitoring program-organization |
| Dec 6, 2022 | Lake Merced East "E" | Danger | Updates from routine monitoring program-organization |
| Oct 1, 2022 | Lake Merced East "E" | Danger | Updates from routine monitoring program-organization |
| May 25, 2022 | Lake Merced East "E" | Caution | Updates from routine monitoring program-organization |
| Jul 9, 2021 | Lake Merced, "north" portion of lake | Danger | Advisory based on visual and toxins |
| Jul 9, 2021 | Lake Merced, "east" portion of lake | Danger | 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.