Save Our Water question: Why does the water from Lake O cause algae blooms? Is the lake polluted?

Amy Bennett Williams
The News-Press
Paul Gray Ph.D., Audubon’s Lake Okeechobee Science Coordinator shows  muck from near the shore of Lake Okeechobee.

Editor's note: The News-Press started this weekly feature to answer water questions, including those submitted by the public during the 2018 Save Our Water Summit. 


Why does the water from Lake O cause the algae blooms? Is Lake O polluted?

Yes, Lake Okeechobee is polluted, and the fact that it's polluted with fertilizer only makes things worse for the Caloosahatchee River.

When the U.S. Army Corps of Engineers steps up lake releases down the river, the Caloosahatchee gets huge doses of nitrogen and phosphorous in that extra water, and just as those elements can green up a lawn, so too with algae.

When lake levels get too high, water managers send the excess down the Caloosahatchee and St. Lucie rivers, which can cause a variety of woes, including algae blooms.

This year, Hurricane Irma's heavy rains have made things worse by washing extra nutrients into the 300,000-acre lake from developments and farm fields, "so the lake's been more or less freshly fertilized," said Paul Gray, Audubon Florida's Okeechobee science coordinator.

Health officials on algae: 'dodge it'

"The reason we're having a bloom now (is) we had big gushes of water into the lake before summer that carried in a whole lot of nutrients," Gray said, "so now, when the summer sunlight and warmth get to it, that fertilizer takes off into an algae bloom."

Even in years without extraordinary rainfalls, the water is polluted by mud on the lake’s bottom. This dark ooze contains a number of pollutants, and because the lake is so shallow, wind and waves keep that mud stirred up and suspended.

To make matters worse, a giant algae bloom is flourishing in the lake itself.

"The open water of the lake is like 300,000 acres (and) at least half of that is covered in algae," Gray said, "like 200 square miles."

Lake Okeechobee algae bloom could be spreading

Fixing the problem will take a multi-faceted approach, Gray said, and one key component of that will be building a reservoir to hold excess lake water, which would take some of the pressure off the rivers and their estuaries.

Save Our Water

"There's all kinds of bickering about how effective it'll be or whatever, but it's one of many things we need to do," Gray said, "Because until we start having options like that during these events, we're just stuck where we are.

"If you think about it, this water management system was designed in the 1940s, and we're still driving it," he said. "We need a new car."       

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