Heavy rainfall over the weekend pushed the level of Lake Okeechobee higher. Some parts of Okeechobee County reported 4 inches of rainfall on Saturday and Sunday.

According to the South Florida Water Management District data, for the seven-day period ending Oct. 1, direct rainfall added 117,120 acre feet into Lake Okeechobee. Surface water inflows from the north added 92,140 acre feet.

Meanwhile very little water is leaving the lake as rainfall is taking up capacity south and west of the lake.  During that seven-day period, evapotranspiration (a combination of evaporation and plant transpiration) removed 28,160 acre feet of water from the lake. Flow south accounted for 90 acre feet. No lake water was released east. About 470 acre feet was released west to the Caloosahatchee.

Heavy rainfall in the local basin also impacted the Calooshatchee River. For the seven-day period ending Oct. 3, flow at the Franklin Lock averaged 6,541 cubic feet per second with more than 99% of the water coming from local basin runoff. Lake Okeechobee releases accounted for just 10 cfs. The target flow for the Caloosahatchee is 2,000 cfs, measured at the Franklin Lock, which is more than 43 miles from Lake O. If local basin runoff meets or exceeds the 2,000 cfs target, no water is released from Lake Okeechobee through the Julian Keen Jr. Lock at Moore Haven.

For that seven-day period, no lake water was released to the C-44 canal (St. Lucie canal) at Port Mayaca.

On Monday, inflows into Lake O from the Kissimmee River averaged 3,073 cfs; inflows from Lake Istokpoga averaged 4,438 cfs; inflows from Fisheating Creek averaged 2,545 cfs.

South of the lake, heavy rainfall also pushed the water conservation areas (WCAs) higher, with all WCAs between the Everglades Agricultural Area and Everglades National Park now above schedule.

From Sept. 25 through Oct. 1, direct rainfall contributed 117,620 acre feet of water to the WCAs. Flow south from the WCAs into Everglades National Park totaled 48,390 acre feet. Evapotranspiration removed 38,130 acre feet.

Lake Okeechobee was 15.90 feet above sea level on Monday. The ecological envelope for Lake Okeechobee is 12 feet to 15.5 feet. When the lake is at 15.5 feet, the marshes are inundated with water. As the lake level rises, water is pushed up against the side of the dike. High water levels can damage or destroy the marshy vegetation around the edges as well as the submerged aquatic vegetation (SAV) which acts as a natural filter for lake water. If the water rises faster than the SAV can grow, the water blocks sunlight to the SAV.