Lake Howell under health alert for harmful algae toxins, officials say

Harmful blue-green algae toxins prompted a health alert for Lake Howell on June 5, and officials warned residents not to drink, swim, wade or use personal watercraft on the lake. The advisory also said to avoid any visible bloom, the kind that can appear as scum, foam or a paint-like slick on the surface.

The Florida Department of Health in Seminole County issued the warning after a water sample was taken June 3. Health officials said testing was still underway, so conditions could change quickly and caution was needed even before toxins were fully confirmed everywhere in the lake. The alert was aimed at immediate behavior on and around the water, not a long-term fix.

Officials said anyone who touches algae, discolored water or water with a foul smell should wash with soap and water. They also warned residents not to cook or clean dishes with contaminated water, since boiling will not eliminate blue-green algae toxins. Pets and livestock should be kept away from the lake as well.

The state health department says blue-green algae blooms are more common in summer and fall and can be driven by sunny days, warm water, still water and excess nutrients. Even more concerning, blooms are not always visible when toxins are present, which makes a lake like Howell especially risky for people fishing, paddling or letting children play near the shoreline.

The Florida Department of Environmental Protection and its partners sample and test freshwater for blue-green algae, and the Department of Health uses those results to issue health cautions and alerts through county health departments. That response matters in Seminole County, where lakefront neighborhoods and recreation spots often sit close together, turning what looks like a patch of green water into a possible public-health problem for children, older adults, immunocompromised people, pets and wildlife.

Lake Howell has been flagged before. Seminole County issued similar alerts tied to samples taken on May 23, 2024, June 10, 2024, June 26, 2024, July 30, 2024, July 31, 2024 and August 19, 2024. The repeated warnings suggest the lake remains a recurring concern, not a one-time flare-up.

For questions about the alert, DOH-Seminole listed 407-665-3604. Media contact Mirna Chamorro can be reached at mirna.chamorro@flhealth.gov or 407-665-3374.