Is Lake Formosa safe? Toxic algae status
Orange County, Florida. Harmful algal bloom (blue-green algae) reports from the Florida Department of Environmental Protection (DEP).
Data checked 24 October 2026. Florida data is published as a yearly file; current sampling is shown on the DEP dashboard.
18
sampling visits since 2020
9
visits where a bloom was seen
1.2 µg/L
highest microcystin result
Year by year
Each box shows visits where a bloom was seen, out of all sampling visits that year.
Reports at Lake Formosa are most often logged in January, February and March.
Recent reports
| Date | Location | Result |
|---|---|---|
| 12 March 2025 | Lake Formosa - pedestrian bridge | No bloom seen · microcystin not detected |
| 24 February 2025 | Lake Formosa - SW Park | No bloom seen · microcystin not detected |
| 5 February 2025 | Lake Formosa - pedestrian bridge | Bloom seen · microcystin 0.56 µg/L |
| 6 May 2024 | Lake Formosa - pedestrian bridge | Bloom seen · microcystin not detected |
| 29 January 2024 | Lake Formosa - South Central Shore | No bloom seen · microcystin not detected |
| 4 May 2023 | Lake Formosa - SW Park | No bloom seen · microcystin not detected |
| 14 February 2023 | Lake Formosa - pedestrian bridge | Bloom seen · microcystin not detected |
| 31 March 2022 | Lake Formosa - SW Park | No bloom seen · microcystin not detected |
| 21 March 2022 | Lake Formosa - SW Park | No bloom seen · microcystin not detected |
| 8 March 2022 | Lake Formosa - SW Park | Bloom seen · microcystin not detected |
| 24 February 2022 | Lake Formosa - SW Park | Bloom seen · microcystin 1.2 µg/L |
| 10 February 2022 | Lake Formosa - pedestrian bridge | No bloom seen · microcystin not detected |
What the results mean
Staff saw a bloom at the sampling site. A sample may then be tested for toxins.
Microcystin, a liver toxin made by blue-green algae, was found in the sample.
At or above the level where the US EPA recommends swimming advisories for microcystins.
Dogs and toxic algae
Dogs face the greatest risk because they swallow water and lick algae off their fur. If a bloom has been reported, keep dogs out of the water and away from scum on the shore. If your dog swims in water that might have algae, rinse it with clean water straight away and call a vet if it seems unwell.
Common questions
Is Lake Formosa safe to swim in?
The most recent entry in Florida's published data is from 12 March 2025: no bloom seen · microcystin not detected (Lake Formosa - pedestrian bridge). Blooms have been recorded at Lake Formosa in 6 different years, so treat green, scummy or discoloured water with caution. For current conditions, check the DEP Algal Bloom Dashboard and posted signs.
When does Lake Formosa get algae blooms?
In the state's records, reports are most often logged in January, February and March. Blooms are most likely in warm, calm weather, but they can appear at other times of year.
Source: Florida Department of Environmental Protection (DEP), official data. This page is independent and not affiliated with the State of Florida.