Officials try to ready Lake Okeechobee for dangerous rain from Hurricane Matthew

Every time a major hurricane threatens South Florida, one of the big questions is: What about the dike?

A 143-mile-long earthen dike named for former President Herbert Hoover surrounds Lake Okeechobee, the second largest freshwater lake in the United States. The U.S. Army Corps of Engineers manages the lake level, trying to keep it between 12.5 feet and 15.5 feet. The higher the level, the greater the risk of the dike collapsing, sending a massive wave of floodwaters into towns around its edge.

As of Thursday morning, the level was 15.9 feet and rising — beyond the level that officials find comfortable, especially with Hurricane Matthew expected to dump lots more water.

They're already pumping water out of the lake and into the canals that carry it out to the St. Lucie River on the east coast and the Caloosahatchee River on the west coast, according to corps spokesman John Campbell.

On Tuesday, the corps sent inspectors around the the lake to check for signs the Herbert Hoover Dike might be weakening, he said.

"There's always been some minor seepage," Campbell said. "What we're looking for are new spots, and we didn't see anything that would cause any concerns."

But as the storm closes in, he said, the dumping of lake water into the St. Lucie will have to be cut back or even stop. The worry is that the storm surge will push that discharged lake water outward onto the landowners nearby, causing more flooding.

As soon as the storm passes, he said, inspectors will check the dike for damage. High winds can whip up waves that erode the sides, and heavy rains add to the weight of the water pushing outward against the walls.

Just in case, the corps has stockpiled large rocks at locations around the dike for use in plugging any holes, he said. They can be used to temporarily stabilize the dike walls.

"In the late "90s and early 2000s we had to take action to make sure the dike didn't fail," he said.

On the other hand, he said, the lake hit 16.4 feet earlier this summer with no apparent problems.

The corps built the 67.8 miles of dike along the south shore and 15.7 miles along the north between 1932 and 1938. Since 2007, the corps has spent more than $500 million on projects designed to reduce the risk of catastrophic failure, but they are nowhere near done.

Their continued releases of lake water have been blamed for causing the massive toxic algae bloom that forced beaches on the state's east coast to close over the July 4 weekend. While the corps had cut back on the releases prior to Matthew's appearance, a new algae bloom had erupted recently near Stuart.

South Florida's waterways are mostly one large, heavily managed flood control system, run for the past 60 years by the corps and the South Florida Water Management District. Water district officials started flushing water out of canals in anticipation of the hurricane, said spokesman Randy Smith.

The fear behind all this is that there might be a repeat of 1928, when an unnamed hurricane hit. Lake Okeechobee embankments were made of sand and muck, and water overtopped the dikes, pouring into communities south of the lake, killing an estimated 2,500 people.

Zora Neale Hurston, in her novel Their Eyes Were Watching God, depicted that storm in detail. She described the lake as a "monstropolous beast" awakened by the hurricane, "rolling the dikes, rolling the houses, rolling the people in the houses along with other timbers. The sea was walking the earth with a heavy heel.''

Contact Craig Pittman at craig@tampabay.com. Follow @craigtimes.