With Lake Okeechobee almost 3 feet higher than a month ago, the U.S. Army Corps of Engineers began releasing water from the lake this morning to ensure that its 75-year-old dike could safely weather another storm.
“Tropical Storm Isaac provided a classic example of how quickly the lake can rise,” said Lt. Col. Thomas Greco, the Corps’ Deputy District Commander in South Florida. Because the water level can rise six times faster than water can be discharged, “We’ve got to manage it in a manner where we have enough storage for the remaining two months of hurricane season, have enough water for the dry season and be sensitive to the delicate ecosystems in each of the estuaries,” Greco said.
The Corps is responsible for maintaining the Herbert Hoover Dike and managing Lake Okeechobee water levels. To do so, it must also balance the needs of flood control, public safety and navigation. The preferred water levels are between 12.5 and 15.5 feet. Levels above that can threaten the integrity of the dike. On Tuesday the lake stood at 15.1 feet.
Releases will be made to the Caloosahatchee River and St. Lucie Estuary, ecologically vital water bodies that provide habitat for plants and wildlife threatened by changes in salinity levels. Although no water has been released from the lake since Isaac’s record rainfall, salinity levels have already dropped in the St. Lucie estuary, said Mark Perry, Executive Director of the Florida Oceanographic Society.
Storm water runoff from the C-44 canal and the C-23 and C-24 agricultural canals have lowered salinity levels near the Roosevelt Bridge in Stuart to 6 parts per thousand, Perry said. The normal range is 24 parts per thousand. If levels drop below 5 parts per thousand for more than two weeks, the area’s oyster beds — revived by recent restoration programs — could be threatened, Perry said.
“We’re all kind of keeping track of what’s going on,” Perry said, referring to environmentalists who monitor the estuary. Without man-made wetlands or other storage south of the lake to handle storm water runoff, damaging releases to the estuaries will continue. “The Corps has no other place to put the water,” he said.