Lake Okeechobee rose slightly last week due to heavy rainfall, while on the west coast, water managers warned of water shortages.
According to the South Florida Water Management District Environmental Conditions report for the week of Nov. 13-19, the big lake received 55,740 acre feet of water from direct rainfall for that seven-day period. Inflows from the north totaled 31,070 acre feet for that period.
Outflows to the west were 15,010 acre feet. The U.S. Army Corps of Engineers has set the target flow to the Caloosahatchee at the beneficial flow rate of 2,000 cubic feet per second (cfs), measured at the W.P. Franklin lock, which is more than 43 miles from the Julian Keen Jr. Lock at Moore Haven, where the lake meets the river. If local basin runoff meets or exceeds the target, no lake water is released. During the dry season, the Caloosahatchee River needs some freshwater flow from the lake to maintain optimal salinity levels in the estuary
Outflows to the east were 1,360 acre feet. While no lake water was released through the St. Lucie Lock, lake water is sometimes released to the C-44 canal (St. Lucie canal) to maintain the canal level between 14 and 14.5 feet for navigation and water supply.
During that same period, the lake lost 19,020 acre feet to evapotranspiration. Flows south for water supply were 1,270 acre feet.
The area south of Lake O also received heavy rainfall. Direct rainfall for that seven day period contributed 257,540 acre feet of water to the Water Conservation Areas (WCAs). Total inflows to WCA-2A and 3A from the stormwater treatment areas (STAs) was 52,050 acre feet.
Evapotranspiration removed 29,590 acre feet from the WCAs. Flows south were 38,850 acre feet.
Thanks to the federal approval of a temporary deviation in the release schedule, all the flood control structures are open and USACE is maximizing flow under the Tamiami Trail to Everglades National Park. The release schedule called for four flood control structures to be closed this time of year to protect the nesting area of a subpopulation of the endangered Cape Sable Seaside Sparrow. The deviation allows the water control structures to remain open through the end of the year, as well as for 90 non-consecutive days between Jan. 1 and June 1, 2024. This will allow USACE and SFWMD to move water out of WCA-3A into Everglades National Park based on the current conditions rather than on the calendar.
On Nov. 24, Lake Okeechobee was 16.07 feet above sea level. The best levels fro the lake's ecology range from 12 feet to 15.5 feet. When the lake level is above 15.5 feet, water stacks up against the dike, which is damaging to the marshes.
The lake's ecology needs about 60 days with a level below 12.5 feet in order for the sunlight to reach the lake bottom and new submerged aquatic vegetation (SAV) to germinate. That didn't happen this year. The lake started the wet season at 13.7 feet above sea level.