LAKE OKEECHOBEE — With Lake Okeechobee at 16.22 feet above sea level on Nov. 25, it looks like the lake level is finally on a slow decline, due to the releases east and west.
On Oct. 14, with the lake above 16 feet, the U.S. Army Corps of Engineers started releasing water to the St. Lucie and Caloosahatchee Rivers.
How much water has flowed to the coastal estuaries since Oct. 14?
Remember: One inch on Lake Okeechobee equals about 12 billion gallons of water.
Let’s do the math ...
The target flow from the lake at Moore Haven has been set at 4,000 cfs — or 2.152 billion gallons a day.
There has been some fluctuation in flow since Oct. 14.
• For the seven day period ending Oct. 21, flow averaged 3,480 cfs, about 1.872 billion gallons per day or 13.104 billion gallons for the week.
• For the seven day period ending Oct. 28, flow averaged 4,046 cfs, about 2.177 billion gallons per day or 15.239 billion gallons for the week.
• For the seven day period ending Nov. 4, flow averaged 4,031 cfs, about 2.169 billion gallons per day or 15.183 billion gallons for the week.
That totals: 86.107 billion gallons, or about 7 inches on Lake Okeechobee.
The target flow from the lake to the St. Lucie, measured at the St. Lucie Lock, has been set at 1,800 cfs — about 968 million gallons a day. However, the flow at the St. Lucie Lock is NOT all from the lake. It is a mixture of lake water and local basin runoff. When there is a lot of local basin runoff, less water is released from the lake. Lake water enters the St. Lucie (C-44) canal at Port Mayaca. Since Oct. 14, the flow from the lake at Port Mayaca has varied also.
• For the seven day period ending Oct. 21, flow averaged 331 cfs, about 178 million gallons per day or 1.246 billion gallons for the week.
• For the seven day period ending Oct. 28, flow averaged 906 cfs, about 487 million gallons per day or 3.409 billion gallons for the week.
• For the seven day period ending Nov. 4, flow averaged 1,253 cfs, about 674 million gallons per day or 4.718 billion gallons for the week.
• For the seven day period ending Nov. 11, flow averaged 746 cfs, about 401 million gallons per day or 2.807 billion gallons for the week;
• For the seven day period ending Nov. 18, flow averaged 1,404 cfs, about 755 million gallons per day or 5.285 billion gallons for the week;
That totals: 23.485 billion gallons of water, or about 2 inches on Lake Okeechobee.
Note: According to a statement by Col. Andrew Kelly of the U.S. Army Corps of Engineers, during the wet season, enough water from the St. Lucie Canal backflowed into Lake Okeechobee to equal about 6 inches on Lake Okeechobee.
South of the lake, the ground was already saturated before Tropical Storm Eta hit, dropping as much as 18 inches of rainfall in some areas. The WCAs are bordered by the East Coast Protection Levee (which runs from West Palm Beach to Miami) on the east and the Tamiami Trail on the south.
The water conservation areas (WCAs) are south of the Everglades Agricultural Area, which is south of Lake Okeechobee. Canals run through the EAA to the WCAs. WCA-1 flows into WCA-2A. WCA-2A flows into WCA-3A. WCA-2A is currently 2.1 feet above schedule. WCA-3A is currently 2.21 feet above schedule. Water from WCA-3 flows under the Tamiami Trail to Everglades National Park and Big Cypress Preserve.
The Tamiami Trail acts as a dam, transecting the southern Everglades, so water has backed up north of the road. Flow at the bottom of the system under the Tamiami Trail is about 6,000 cfs. That is the maximum the current structures can flow.
Even with the emergency deviation which has kept the water control structures under the trail open — under normal conditions some would have been closed Nov. 1 to protect the nesting grounds of a subpopulation of the endangered Cape Sable sea sparrow — water managers say it could take until January or later to get the WCA water levels down.
Because the water levels in the WCAs are already so high, no water has moved south from the lake to the WCAs since just before Tropical Storm Eta hit. Prior to the storm, the corps and SFWMD were moving as much water as possible south from Lake O.