Whelan Lake: toxic algae advisories
Whelan Lake, San Diego County. See all San Diego County waters.
What the state's records say
Danger advisory, last posted Aug 25, 2026. 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: 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 Whelan Lake
The state has an advisory on file for Whelan Lake (Danger advisory), last posted Aug 25, 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 |
|---|---|
| Center of Lake | Caution advisory, last posted Aug 25, 2026. No all-clear recorded. |
| City of Oceanside San Luis Rey Wastewater Treatment Plant | Danger advisory, last posted Jun 29, 2026. No all-clear recorded. |
| Whelan Lake | Warning advisory, last posted Jul 25, 2019. No all-clear recorded. |
Advisory history
Every advisory record the state has published for Whelan 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 |
|---|---|---|---|
| Aug 25, 2026 | Center of Lake | Caution | Advisory based on visual and toxins; Lake-wide advisory |
| Jun 29, 2026 | City of Oceanside San Luis Rey Wastewater Treatment Plant | Danger | Advisory based on visual and toxins; Floating/planktonic bloom observed; Lake-wide advisory |
| May 12, 2026 | City of Oceanside San Luis Rey Wastewater Treatment Plant | Caution | Advisory based on visual and toxins; Floating/planktonic bloom observed; Lake-wide advisory |
| May 12, 2026 | Center of Lake | Caution | Advisory based on visual and toxins |
| Nov 4, 2025 | City of Oceanside San Luis Rey Wastewater Treatment Plant | None | Advisory based on visual and toxins; Floating/planktonic bloom observed; Lake-wide advisory |
| Oct 28, 2025 | City of Oceanside San Luis Rey Wastewater Treatment Plant | Caution | Advisory based on visual and toxins; Floating/planktonic bloom observed; Lake-wide advisory |
| Jul 8, 2025 | City of Oceanside San Luis Rey Wastewater Treatment Plant | Caution | Advisory based on visual and toxins; Floating/planktonic bloom observed; Lake-wide advisory |
| Jul 8, 2025 | City of Oceanside San Luis Rey Wastewater Treatment Plant | Blank in the state's file | Advisory based on visual and toxins; Floating/planktonic bloom observed; Lake-wide advisory |
| Jul 25, 2019 | Whelan Lake | Warning |
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.