LAKE OKEECHOBEE – Things are looking better on Lake Okeechobee, Col. Andrew Kelly, commander of the U.S. Army Corps of Engineers Jacksonville District. told reporters in a media briefing on Friday, May 21.
“We are in a significantly different place than we were a month ago,” said Kelly, speaking from the Port Mayaca Lock. “The trend line is very positive,” he said.
Lake level and algae conditions both improved in the past few weeks, he explained. A May 17 sample taken at the Port Mayaca lock showed microcystin levels at 2.2 micrograms per liter. A sample taken at the same site on May 3 had 16 micrograms per liter. The World Health Organization considers microcystin levels about 1 microgram per liter to be unsafe to drink and levels above 8 micrograms per liter to be unsafe for human recreational contact (such as swimming.) At the Pahokee marina, where toxin levels were more than 800 micrograms per liter in April, the most recent test on May 19 was 6.6 microgrms per liter.
“The lake is at 13.25 feet,” said Kelly. That’s about a foot lower than it was a month ago, although it is 2.1 feet higher than this date last year.
“As we are going forward, there is a potential to get down to around 13 feet before the rainy season starts,” said the colonel.
Kelly credited the “amazing work SFWMD has done to maximize releases to the south,” for the change in lake level. He said they are averaging about 2,500 cubic feet per second (cfs) flowing south from Lake Okeechobee. About 61% of the flow from the lake is going south, he added. Most of that flow is being used for water supply. About 440 cfs is flowing under the Tamiami Trail.
He said they are moving as much water south as the stormwater treatment areas (STAs) and Water Conservation Areas (WCAs) can handle.
Kelly said the corps will continue to release 1,500 cfs to the Caloosahatchee River, measured at the Franklin Lock. This flow is within the volume of freshwater considered to be beneficial to the Caloosahatchee estuaries. The Caloosahatchee River needs some freshwater flow from the lake in the dry season. Flows below 450 cfs are deemed harmful because the salinity levels rise too high. Flows above 2,800 cfs are considered harmful because the salinity levels drop too low. Lee County officials have requested a freshwater flow in the dry season of at least 1,000 cfs.
The Franklin Lock is 43.4 miles from the Moore Haven Lock, where water from the lake enters the river. If there is enough basin runoff for flow to meet the target flow at the Franklin Lock, no lake water will be released at Moore Haven.
No lake water will be released to the St. Lucie River at the St. Lucie Lock. There is some flow from the lake at Port Mayaca into the St. Lucie Canal to meet water supply needs in that basin. For the past seven days (ending May 21), average flow at Port Mayaca into the C-44 canal has been 74 cfs. Kelly said permitted water users draw water from the C-44 canal.
“If it stays dry, more water is pulled from the C-44,” he explained. The corps tries to keep the C-44 canal between 14 feet and 14.5 feet above sea level, for navigation and water supply. If there is a rain event, since the lake is below 14 feet, excess water will flow from the C-44 back into the lake.
Flow back and forth at Port Mayaca is common depending on the time of year, the lake level and the amount of rain in the C-44 basin. During the past water year, about 100,000 acre feet of water flowed from the C-44 canal into Lake Okeechobee; and about 200,000 acre feet of water flowed from the lake into the C-44 canal.
“We are keeping S-80 (St. Lucie Lock) closed,” said Kelly. All water currently flowing into the St. Lucie River is from the local basins.