LAKE OKEECHOBEE — As the current level of Lake Okeechobee continues to drop, decisions made last week by government agencies could impact the big lake’s future.
Last week the U.S. Army Corps of Engineers Jacksonville District announced the approval of a planned temporary deviation to the 1981 Lake Kissimmee, Hatchineha and Cypress Interim Regulation Schedule. More water will be held temporarily in the lakes in order to control the water flow in the Kissimmee River while construction work is underway on river restoration projects. The restoration will put the curves back into the middle third of the river, but filling in the channel to force water back into the original river oxbows. Slowing the flow will cause the river to spread out over the historic floodplain in that area. While the river restoration is not a water quality project, slowing the flow many have some benefit to water quality as plants in the flood plain absorb nutrients from the water. The restoration is projected to be completed by the end of the year.
On April 15, the corps reported the RECOVER Lake Okeechobee Stage Performance Measure has been approved, with scientists recommending the minimum target level for Lake O at 12 feet. The RECOVER team conducts scientific and technical evaluations and assessments for improving CERP’s ability to restore, preserve and protect the South Florida ecosystem while providing for the region’s other water-related needs.
The corps is currently developing the Lake Okeechobee Systems Operating Manual (LOSOM), which is expected to be ready by the end of 2022, when repairs of the Herbert Hoover Dike are expected to be complete. Some east coast officials, along with Congressman Brian Mast, have argued for a minimum lake level of 10.5 feet, which has been a source of great concern to those who depend on the lake for water supply.
Little of the rain that fell north of Lake Okeechobee over the weekend drained into the lake; the ground was so dry that it absorbed most of the rain as it fell. But recent rainfall into the Big O was sufficient to raise it from 11.34 feet on Saturday to 11.41 feet on Tuesday. Even with the boost from the storms, the lake level fell slightly from last Tuesday’s level of 11.44 ft. level.
For the seven day average ending on April 21, the average flow from the lake to the Caloosahatchee River was 578 cubic feet per second. Some of that water was lost along the way to the Franklin Lock, which is 43.4 miles from Moore Haven. Average flow at the Franklin Lock was 208 cfs.
No water from the lake has been released to the St. Lucie river at the St. Lucie Lock in more than a year. If there is rain in the C-44 basins, water sometimes backflows from the St. Lucie Canal into Lake Okeechobee when the lake is below 12 feet. If the water level in the canal falls lower than the lake level, water managers release lake water into the St. Lucie Canal to maintain the water level in the canal for navigation. On average, for the seven-day period ending April 21, flow from the lake to the St. Lucie canal averaged 32 cfs. However, on April 21, water from the canal was backflowing into the lake at a rate of 197 cfs.
National Atmospheric and Oceanic Administration (NOAA) satellite imagery indicates low potential of algae blooms on the northwest shore of the lake. The satellite imagery predicts the potential for a bloom based on chlorophyll levels. Areas with bloom “potential” on the satellite image do not always have visible algae on the surface.
• On April 14, Lee County staff collected a sample at the Caloosahatchee River-Alva Boat Ramp where algae were observed forming streaks and accumulating along the shoreline. No cyanotoxins were detected. The sample was co-dominated by Microcystis aeruginosa and Cylindrospermopsis raciborskii.
• SFWMD staff sampled a visible algae bloom in south Lake Okeechobee about 2 miles northeast of Ritta Island on April 8. Tests indicated mixed algae with no dominant species. Total microcystin was barely detectable at 0.33 micrograms per liter; the World Health Organization has set 8 micrograms per liter as the safe level for human recreational contact.
• Microcystis aeruginosa was the dominant taxon in a sample taken from an algae bloom on Lake Okeechobee west of Sand Point on April 8. Microcystin was barely detectable at 0.42 micrograms per liter.