LAKE OKEECHOBEE — As Lake Okeechobee’s level continues to fall, the U.S. Army Corps of Engineers has reduced the flow from the lake to the Caloosahatchee River to the minimum of 457 cubic feet per second set by the South Florida Water Management District.
Because the flow is measured at the Franklin Lock (which is 43.4 miles from Moore Haven), if there is any rainfall in the Caloosahatchee River basin, less water can be released from the lake. However, if there is no rain in the basin, more water may be released from the lake to keep the flow at the Franklin Lock at the minimum, as some water may be lost along the way. For example, for the seven-day period ending April 7, the average flow from the lake at the Moore Haven lock was 868 cfs and the average flow at the Franklin Lock was 414 cfs.
For most of the current dry season, the corps had been releasing enough water from Lake Okeechobee to maintain an average of 600 to 650 cfs at the Franklin Lock to maintain beneficial salinity levels in the Caloosahatchee River estuaries. On April 2, the flow was reduced to the 457 cfs minimum required level.
“This is a minor alteration to the actions we’ve been taking since the dry season began. Specifically, we are reducing release quantities from 600 cfs to 450 cfs in order to conserve water for water supply,” said Col. Andrew Kelly, Jacksonville District commander. “After the driest March in the last 90-plus years, we’ve seen the recession rate on the lake increase in the past few weeks and we anticipate the lake levels this year to be very similar to last year when the wet season arrives. A lot can change, of course, but we’re taking the next step to continue to conserve water.”
There has been no flow from the river to the St. Lucie River during the dry season, but due to the low lake level there has been backflow from the St. Lucie (C-44) Canal into Lake Okeechobee at Port Mayaca. For the seven-day period ending April 7, the average flow into the lake from the C-44 canal was 117 cfs.
March was one of the driest on record, with only 10 percent of average rainfall and high evapotranspiration, driving Lake Okeechobee elevation down 0.77 feet for the 30 days leading up to April 1. The lake elevation April 1 was 11.87 feet, only slightly above the Water Shortage Management Band of the 2008 Lake Okeechobee Regulation Schedule, according to the corps report. On April 7, the lake level was 11.70 feet.
Satellite images for Lake Okeechobee from the National Oceanic and Atmospheric Administration show low potential for algae blooms on the big lake. Algae is always present in Lake Okeechobee as it is present in all freshwater systems. Algae is part of the natural food chain in both freshwater and the oceans. With the right conditions — high levels of phosphorus and nitrogen, hot weather and little water movement — algae can reproduce rapidly into what is referred to as a “bloom.”
While small algae blooms are common and short-lived on the lake during hot weather, large blooms can create problems throughout the waterway. Cyanobacteria, commonly called blue-green algae, is the oldest life form on Earth. Some types of cynaobacteria found in the Lake Okeechobee Waterway, which includes the Caloosahatchee River, Lake Okeechobee, the St. Lucie Canal and the St. Lucie River, can produce toxins; but even those that can produce toxins do not always do so.
If an algae bloom is reported, the Florida Department of Environmental Regulation samples the water to test for the type of algae present and whether any toxins are present. Regular sampling is also done at established collection sites throughout the Lake Okeechobee Waterway.
As of April 7, there were no reported algae blooms and no reported toxins in Lake Okeechobee, the Caloosahatchee or the St. Lucie, according to the FDEP website that tracks algae blooms and testing. The most recent algae bloom reported in the Caloosahatchee was on March 10, upstream of the Franklin Locks. The dominant species was Microcystis aeruginosa. No toxins were detected.