SANIBEL-CAPTIVA CONSERVATION FOUNDATION The Franklin Lock (S-79) on Feb. 21.

On Feb. 17, faced with large amounts of projected rainfall, the U.S. Army Corps of Engineers began releasing water from Lake Okeechobee. The Sanibel-Captiva Conservation Foundation reported that the releases were deemed necessary due to the elevated height of the lake — which had reached over 16.3 feet — and the risk of the lake continuing to rise with the start of the wet season.

“Normally, winter is the dry season in South Florida, a time that water managers are able to lower the lake by sending water south into the Everglades Agricultural Area, and through the natural processes of evapotranspiration,” SCCF Environmental Policy Director Matt DePaolis said. “But this year, as projected, an El Niño brought large amounts of rainfall that prevented the usual dry season drawdown.”

The SCCF reported that despite repeated requests from it and other advocates to try to bring down the lake earlier in the season, releases were withheld, and the lake rose dangerously high.

“While we understand the lake needs to be lowered, care must be taken to not sacrifice the northern estuaries,” he said.

As of Feb. 17, the Corps was releasing the maximum flows from the lake possible under LORS08 — the current release management schedule — which is an average of 4,000 cubic feet per second (cfs) west to the Caloosahatchee Estuary and 1,800 cfs east to the St. Lucie Estuary. It also decided to “pulse” the water out of lake, which means the Corps aims to average 4,000 cfs over 14 days, starting with releases of 6,500 cfs and tapering them down to zero for a period of four days.

SANIBEL-CAPTIVA CONSERVATION FOUNDATION Lake Okeechobee flows take about seven days to reach the mouth of the Caloosahatchee, so the recent increased flows have been due to basin runoff. Water clarity and color depends on many factors.

“This is the announcement we were afraid we were going to get, especially concerning the amount of water we have received in the Caloosahatchee water basin. While the USACE will be releasing 4,000 cfs from the lake, by the time it travels down the river, these flows will have been augmented with basin runoff to much greater rates. After the rains this weekend, we’re already seeing flow rates of over 7,300 cfs at the beginning of the Caloosahatchee estuary — prior to the Lake Okeechobee releases reaching our waters,” DePaolis said on Feb. 21.

The SCCF reported that the releases are coming at a precarious time for the estuary.

– Many important fish species such as menhaden, sheepshead and tarpon are in important stages of their life cycle.

– Oysters are making gametes in anticipation of their spawn that will begin to occur in April.

– Seagrasses are still slowly recovering from previous storms, algal blooms and releases.

“All of these organisms and more could be detrimentally impacted by large, sustained releases,” he said. “It will be imperative that the USACE work with stakeholders to understand the full ramifications of their decisions and adapt them to changing estuary conditions.”

DePaolis explained that for “pulse” releases to work, appropriate recovery times must be incorporated into the planning. To protect the oyster spawn, it will be necessary to end the releases prior to the spat arriving. He added that to protect communities and environments, the Corps must be responsive to any change in conditions that signal a potential risk of red tide.

“In addition to careful planning and responsive management, the Corps must utilize every means to lower the lake possible, including storing water in the storm water treatment areas and canals that have capacity south of the lake, to distribute the burden of the releases,” DePaolis said.

The SCCF reported that it will continue to engage with the Corps to provide recommendations to protect the health and safety of the estuaries.