Lake Okeechobee is rapidly rising as runoff from Hurricane Ian flows south from Orlando/Kissimmee. The rapid flow of water south is also impacting the dissolved oxygen levels in the Kissimmee River.
The Oct. 5 Environmental Conditions report by the South Florida Water Management District stated: “Hurricane Ian passed over the Kissimmee Basin on Sept. 28-29, 2022, bringing considerable rainfall that raised water levels in East Lake Toho (S-59), Lake Toho (S-61) and KCH (S-65) further above their respective regulation schedules; discharge at their outlet structures is being adjusted to bring stage in each lake back to its respective regulation schedule. S-65A discharge was increased to 10,000 cfs to control a rainfall driven stage rise in Pool A. With S-65A discharge continuing to rise above bankfull, water depth on the Kissimmee River floodplain rose to a mean depth of 4.11 feet on Oct. 2, 2022. The average concentration of dissolved oxygen in the Kissimmee River declined from 3.0 mg/L to 2.5 mg/L as Hurricane Ian passed over the basin and then decreased to 0.7 mg/L, well below the potentially lethal level for largemouth bass of 1.0 mg/L.”
“We’ve had a historic rainfall in the upper Kissimmee Basin,” Lt. Col. Todd Polk, deputy commander of the U. S. Army Corps of Engineers Jacksonville District, explained in an Oct. 7 media briefing.
He said district-wide, rainfall from the hurricane averaged about 13.5 inches, with heavier rainfall in the Kissimmee/Orlando area and lighter rainfall closer to Lake Okeechobee.
“There is a lot of water in the system, particularly in the chain of lakes,” he explained.
Water managers have installed pumps to speed water through the canals that connect the chain of lakes and send water south into the Kissimmee River.
In the Kissimmee Chain of Lakes:
• Lake Toho is 2.73 feet above schedule and receding.
• East Lake Toho is 3.64 feet above schedule and receding.
• Lake Hart and Mary Jane are 3.66 feet above schedule and stabilizing.
• Lakes Myrtle, Preston, and Joel are 4.47 feet above schedule and stabilizing.
• Lake Kissimmee is 2.35 feet above schedule and climbing.
The Kissimmee River flood plain is completely inundated. “Tree line to tree line is full,” said Polk.
On Oct. 7 Lake Okeechobee was at 14.29 feet above sea level, about 7.5 inches higher than one week ago and about 1 foot and 9 inches higher than 30 days ago.
“The lake is coming up fast,” said Polk. However, he added due to the drier than normal conditions earlier in the wet season, there was plenty of capacity in the big lake before the storm hit.
From the north, flow into the lake is averaging around 17,000 cubic feet per second (cfs), said Polk. That’s about 11 billion gallons of water per day. One inch of water on Lake Okeechobee is about 12 billion gallons. On Oct. 7, inflow was 19,737 cfs.
Polk said water managers plan to hold the water from Hurricane Ian in the lake. There are no plans at this time to release lake water east or west.
No lake water has been released to the St. Lucie River since April 2021. This wet season, USACE has been pumping water into the C-44 reservoir in Martin County. On Oct. 7, the S-401 pump station was moving 650 cfs from the C-44 canal into the C-44 reservoir. As of Oct. 7, this above ground reservoir was about 7.6 feet deep. The 3,400 acre C-44 reservoir can hold water up to 15 feet deep. According to USACE, water is not currently being released from the reservoir to the stormwater treatment areas (STAs) as the STAs are full from rainfall. The S-404 pump station is releasing about 90 cfs from the STAs back into the C-44 canal. This water was from direct rainfall into the STAs.
Lake releases to the Caloosahatchee during the dry season were for beneficial flow to the estuaries. This wet season, if local basin runoff met the minimum flow requirement at the Franklin Lock (more than 40 miles from Lake Okeechobee), no lake water has been released to the Caloosahatchee.
For the seven day period ending Oct. 7, flow at the Franklin Lock averaged 7,555 cubic feet per second (cfs), all from local basin runoff.
To the east, water flowing through the St. Lucie Lock is from local basin runoff. For the seven-day period ending Oct. 7, flow through the St. Lucie lock averaged 135 cfs. When the level of Lake Okeechobee is below 14 feet, local basin runoff to the C-44 canal (St. Lucie Canal), back flows into Lake Okeechobee. Since the lake level has exceeded 14 feet, that option is not available. Water managers try to keep the C-44 canal at about 14 feet above sea level.
Polk said there are some areas in the lake with potential for algal blooms but recent samples from Lake Okeechobee detected no toxins.
South of the lake, 100,000 acre feet of water moved under the Tamiami Trail in September. With Water Conservation Area (WCA) 3A above schedule, water is moving under the trail at the maximum capacity.