Lower Otay Reservoir: toxic algae advisories
Lower Otay Reservoir, San Diego County. See all San Diego County waters.
What the state's records say
Warning advisory, last posted Jul 11, 2025. 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 harm people and animals. Do not swim or let children or pets in the water, and stay away from scum.
Before you go, check the state's official algae page and any signs posted at the water.
Dogs at Lower Otay Reservoir
The state has an advisory on file for Lower Otay Reservoir (Warning advisory), last posted Jul 11, 2025, 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 |
|---|---|
| reservoir-wide | Warning advisory, last posted Jul 11, 2025. No all-clear recorded. |
| Spot not described | The state's latest record, from Feb 25, 2022, recommends no advisory. |
Advisory history
Every advisory record the state has published for Lower Otay 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 |
|---|---|---|---|
| Jul 11, 2025 | reservoir-wide | Warning | Lake-wide advisory |
| Jul 2, 2025 | reservoir-wide | Warning | Lake-wide advisory |
| Jun 2, 2025 | reservoir-wide | Warning | Lake-wide advisory |
| May 29, 2025 | reservoir-wide | Warning | Lake-wide advisory |
| May 23, 2025 | reservoir-wide | Warning | Lake-wide advisory |
| Apr 22, 2025 | reservoir-wide | Warning | Lake-wide advisory |
| Apr 16, 2025 | reservoir-wide | Warning | Lake-wide advisory |
| Aug 25, 2023 | reservoir-wide | None | End date recorded: Aug 25, 2023. Lake-wide advisory; Updates from routine monitoring program-organization |
| Jul 31, 2023 | reservoir-wide | Caution | Lake-wide advisory; Updates from routine monitoring program-organization |
| Jul 17, 2023 | reservoir-wide | Caution | Lake-wide advisory; Updates from routine monitoring program-organization |
| Jul 10, 2023 | reservoir-wide | Caution | Lake-wide advisory; Updates from routine monitoring program-organization |
| Jul 5, 2023 | reservoir-wide | Caution | Lake-wide advisory; Updates from routine monitoring program-organization |
| Jun 8, 2023 | reservoir-wide | Caution | Lake-wide advisory; Updates from routine monitoring program-organization |
| Jun 8, 2023 | reservoir-wide | Caution | Updates from routine monitoring program-organization |
| Jun 1, 2023 | reservoir-wide | Caution | Updates from routine monitoring program-organization |
| Feb 25, 2022 | Spot not described | None | End date recorded: Feb 25, 2022. Advisory based on visual and toxins |
| Feb 25, 2022 | Spot not described | None | 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.