JACKSONVILLE — The U.S. Army Corps of Engineers will continue to release water east to the St. Lucie River and west to the Caloosahatchee River longer than originally anticipated, U.S. Army Corps of Engineers Jacksonville District Commander Col. Andrew Kelly explained in a media briefing on Nov. 19.
The target flow to the east at Port Mayaca is 1,800 cubic feet per second (cfs). The target flow to the west at Moore Haven is 4,000 cfs. Rainfall in the basin, tides and other factors can affect those releases. For the past seven days, the average flow at Port Mayaca has been 1,404 cfs and the average flow at Moore Haven has been 3.321 cfs.
The flow into the St. Lucie River at the St. Lucie Lock is a mixture of lake water, which enters the St. Lucie Canal at Port Mayaca, and local basin runoff. Port Mayaca is 23.9 miles from the St. Lucie Lock.
The flow into the Caloosahatchee estuary at the Franklin Lock is also a mix of lake water and basin runoff. The Moore Haven Lock is 43.4 miles from the Franklin Lock.
“The lake right now is at 16.34 feet (above sea level). It’s a little bit lower than last Friday and we’ve actually come down by about one-tenth of a foot since a month ago, but to put that in reference, we are 3 feet higher than last year,” Kelly said.
In October, the region received 175% of normal precipitation, he explained. In November, so far, rainfall has been 553% of average. The rainfall received so far in November has equaled the average rainfall for November, December and January combined.
He said these extraordinary events over the past two months changed the dynamics of the lake management plan.
He said that, due to extremely heavy rainfall south of the lake during Tropical Storm Eta, the area south of the lake is very wet. The Water Conservation Areas (WCAs) south of the Everglades Agricultural Area are more than 2 feet higher than schedule. It may take months to get the water levels down south of the lake. He said the corps and the South Florida Water Management District are moving water as fast as possible to lower the levels in the WCAs.
“At the same time we are going to be continuing to manage the lake accordingly,” he said.
Col. Kelly said they do not know when the wet season will end.
“We anticipate a staged reduction over a longer period of time,” he said of the of the lake releases. “We are working with the scientists on both sides to consider pausing the releases temporarily to allow the estuaries to recover.”
He said more water from the lake goes to the west than the east because “bottom line is, the pipe is bigger on the west than it is on the east.
“If you cut off to the east, or pause to the east, the reaction is much quicker because the flows are smaller,” he explained.
Releases to the south are not going to be practical for a while, Kelly said. “We have to think where we want to be at the end of the dry season. We don’t want to end the dry season with the lake at a very high level.
“Ending the dry season above 13 feet would not be the best position,” he said.
He said the emergency deviation, which allowed the corps to keep the S-12 gates open instead of closing them in November to protect the nesting grounds of the Cape Sable seaside sparrow, has moved about 40,000 acre-feet of water out of WCA-3A. Even with that additional flow, WCA 3-1 was at 12.77 feet on Thursday, when the schedule calls for a target of 10.50 feet.
Kelly said water managers have to stay flexible.
“We’re always one storm away from a change of a decision,” he said. “We will adjust and adapt to the conditions on the ground.”