Hurricane Idalia Threatens to Stir Up Lake Okeechobee’s Toxic Algae Blooms

For much of the summer, Lake Okeechobee suffocates under toxic, blue-green algae blooms fed by fertilizer runoff from farms. The blooms recently subsided, but Hurricane Idalia could cause further cycles of growth and rot.

That’s because storms can send additional fertilizer runoff down the Kissimmee River and other waterways, stir up pollution from the lake bottom and kill aquatic vegetation — all of which encourage the growth of algae.

The blue-green blooms, also called cyanobacteria, can kill wildlife. For humans, long-term exposure — through skin contact, drinking water, eating contaminated food, or breathing airborne particles — can cause liver damage and neurological disease.

As of Tuesday morning, the water level in Lake Okeechobee was just over 15 feet above sea level, about a foot below where it could endanger the surrounding dike. If rain from Idalia threatens to raise the level to 16.5 feet, the United States Army Corps of Engineers will very likely release water through canals toward Fort Myers and Stuart.

The Army Corps of Engineers did not immediately respond to requests for comment, but officials said during a briefing on Friday that they would probably wait for Idalia to pass before deciding whether to release water.

If a lot of rain falls, lake water and algae could also flow south to the Everglades, an important reservoir of biodiversity, though releases to the east and west are more likely.

“We’ve really been on edge,” said Eve Samples, executive director of Friends of the Everglades, based in Stuart. “We’ve been bracing ourselves for a storm to emerge and make things dire.”