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Army Corps ends LORS deviation releases

By USACE - | Apr 13, 2021

On April 9, the U.S. Army Corps of Engineers’ Jacksonville District reported that it will end advance releases as of April 10 that it had been making under the Lake Okeechobee Regulation Schedule Harmful Algal Bloom deviation.

Releases to the Caloosahatchee will be reduced to 1,000 cubic feet per second (cfs) as measured at the W.P. Franklin Lock and Dam (S-79) to provide the fresh water needed to maintain salinity levels in the estuary, and lake releases through the St. Lucie Lock and Dam (S-80) will stop completely. As is always the case, rainfall could still cause local area runoff that will cause higher than targeted flows to both estuaries.

The advanced releases began in February as part of a planned deviation approved in September to reduce the risk of lake releases when harmful algal blooms are more likely to be present this summer. The deviation released about 91,000 more acre feet of water from the lake than would have normally been released under LORS.

Use of the deviation was limited by a requirement to maintain a recession rate of no more than 0.5 feet per month to avoid harm to nesting birds. As of April 9, the lake stage was at 14.19 feet. The lake has fallen 0.94 feet in the past 30 days. It was still 2.59 feet higher than it was one year ago and 2.41 feet higher than it was two years ago.

The recession rate is now being driven more by evapotranspiration and water supply than by releases, so the tool is no longer available for use until the rate returns to below 1/2 foot per month. The 91,000 acre feet released under the deviation will be available in a bank to reduce releases that would need to be made under LORS this summer.

Water continues to go south to the water conservation areas and Everglades National Park, and the Army Corps will continue monitoring conditions on the lake and in the estuaries, as well as forecasts, and adjust operations, as necessary. This includes the possibility of resuming releases under the deviation should conditions become favorable.

Army Corps operators continue to monitor for algae at USACE structures and facilities and report any visible algae to partners at the Florida Department of Environmental Protection for testing. Results from earlier last week are available on the FDEP dashboard and show very low levels of microcystin at Port Mayaca Lock and Dam and Moore Haven Lock and Dam.