Corps seeks lake level deviations

Posted 8/7/19

JACKSONVILLE — The U.S. Army Corps of Engineers is seeking more flexibility in the operation of Lake Okeechobee releases when harmful algal blooms (HABs) are present or even when HABs are …

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Corps seeks lake level deviations


JACKSONVILLE — The U.S. Army Corps of Engineers is seeking more flexibility in the operation of Lake Okeechobee releases when harmful algal blooms (HABs) are present or even when HABs are “anticipated to occur.”

“We are working closely with our federal, state and tribal interests to maximize our operational flexibility,” said Col. Andrew Kelly, Jacksonville District commander. “We must still meet the Congressionally-authorized project purposes while operating to try to minimize potential health effects associated with harmful algae blooms.”

On Tuesday, the corps posted a draft Environmental Assessment (EA) and proposed Finding of No Significant Impact (FONSI) online, related to proposed deviations in the Lake Okeechobee Regulation Schedule 2008 (LORS 2008). The proposed deviations would allow the corps to release less water when HABs are present and more water when there are no HABs present. In general, that means fewer releases in the hotter summer months when algal blooms are more common and more releases during the winter months when HABs are less likely.

Cyanobacteria (also called blue green algae) are present in the lake year round. Cyanobacteria and algae are part of the natural ecosystem of all freshwater lakes. Cyanobacteria are more likely to reproduce rapidly into a “bloom” during the hotter wet season months. Cyanobacteria blooms are common on Lake O during the summer, but most blooms contain no toxins or very low toxin levels. Researchers from the U.S. Geological Survey have documented 28 different species of cyanobacteria in the Lake Okeechobee Waterway, which includes the Caloosahatchee River, Lake O, the St. Lucie Canal and the St. Lucie River. About 25 percent of the known species of cyanobacteria are capable of producing toxins. However, cyanobacteria that can produce toxins, do not always do so. In 2016 and 2017, cyanobacteria in water from Lake Okeechobee (that was not producing toxins in the lake or producing very low levels of toxins) were believed to seed cyanobacteria blooms on the coast that became highly toxic.

What is considered a HAB? The EA does not set specific sizes or toxin levels. It states: “The corps will consult with partners on the latest science and tools predicting potential and/or indicating actual HAB presence on the lake and estuaries. Current tools available include National Oceanic and Atmospheric Administration’s (NOAA) remote sensing assessment of HAB potential on the lake and estuaries as well as monitoring of HAB occurrence by the South Florida Water Management District (SFWMD) and Florida Department of Environmental Protection (FDEP).”

The NOAA imagery uses data collected by satellite to determine the probability of cyanobactera in the water. It does not indicate what species of cyanobacteria are present. NOAA imagery does not indicate if toxins are present.

The EA also indicates the corps will rely on regular meetings with stakeholders to determine when HAB operations may be warranted.

Releasing more water to tide during the dry season comes with a risk. If water managers guess wrong about the next rainy season, releasing too much water from Lake Okeechobee to tide during the dry season could increase the possibility of water shortages during a drought.

Over the past dry season, the corps released more water west to the Caloosahatchee River than the current schedule dictates. South Florida Water Management District has guaranteed the river a minimum flow of 450 cfs during the dry season. For most of the past dry season, the flow was 800 to 1,000 cubic feet per second, measured at the Franklin Lock. The 1,000 cfs level is considered the optimal flow to prevent salt water intrusion in the river and maintain desired salinity levels in the estuaries. For six weeks in February and March, additional lake water was sent to tide in an attempt to lower Lake Okeechobee before the start of the wet season. These releases occurred when the lake level was below 13 feet above sea level, and LORS 2008 did not call for releasing any freshwater to tide, (apart from the 450 cfs guaranteed to the Caloosahatchee River.) For six weeks in February and March, the corps increased the Caloosahatchee flow to 1,800 cfs. For 21 days in February and March, the corps released 500 cfs east at Port Mayaca to the St. Lucie Canal. For another three weeks in March, flow to the St. Lucie was 250 cfs.

At the time Lt. Col. Jennifer Reynolds told the County Coalition for the Responsible Management of Lake Okeechobee, the Caloosahatchee and St. Lucie Estuaries and the St. Worth Lagoon, these releases were a one-time strategy to help the lake’s marshes recover from the damage of Hurricane Irma. The deviation to LORS 2008 would mean the releases could happen every year.

Under the deviation, the corps proposes to implement the following actions if conditions are met for HAB Operations:
• Within existing flexibility, limit or suspend releases east and west from Lake Okeechobee when HABs are present and LORS guidance allows for releases.
• Limited releases east and west to 2,000 cfs measured at W.P. Franklin Lock & Dam (S-79) near Fort Myers and up to 730 cfs measured at St. Lucie Lock & Dam (S-80) near Stuart. This would only be applicable when LORS guidance suggests releases of 450 cfs measured at Franklin and 200 cfs measured at St. Lucie.
• Allow the flexibility to make up to maximum practicable releases south to the water conservation areas when LORS guidance does not recommend release (contingent upon conditions).
• Maintain this flexibility until LORS 2008 is replaced by a new water control plan (to be called LOSOM — Lake Okeechobee System Operating Manual) estimated for completion in 2022.

According to the corps, these larger releases ahead of time would allow greater flexibility so that less water would need to be released during times when HABs are present in the lake or estuaries. The cumulative volume of water released under the planned deviation will be tracked against the volume held back, that would have been released under LORS 2008. The objective is to reach a net zero balance such that the total volume released across a 12-month period is unchanged from the releases that would have taken place under the existing schedule.

According to the press release, HAB operations could be utilized if any one of the following conditions were present:
• If a HAB is currently in Lake Okeechobee, C-43, C-44, the Caloosahatchee Estuary or the St. Lucie Estuary.

• If the State of Florida declares a state of emergency due to HABs on Lake Okeechobee, C-43, C-44, the Caloosahatchee Estuary or the St. Lucie Estuary.
• If a HAB is anticipated to occur on Lake Okeechobee, C-43, C-44, the Caloosahatchee Estuary or the St. Lucie Estuary.
• If a HAB has occurred and caused harm, or has impacted public safety during the last 18 months within Lake Okeechobee, C-43, C-44, the Caloosahatchee Estuary or the St. Lucie Estuary.

If approved, this deviation would be in effect until a new regulation schedule, the Lake Okeechobee System Operating Manual or LOSOM, is approved. LOSOM is scheduled to be ready when the Herbert Hoover Dike repairs are complete in 2022.

“We don’t know if or when we would need to implement this deviation, but we need to have the ability to do so when the environmental conditions make it necessary,” said Col. Kelly. “Although the lake seems very low, a not so uncommon eight-inch rainfall event in the Kissimmee basin could easily result in a two-foot rise in the lake. In August, that could reasonably be coupled with HABs in multiple locations. We want to have additional tools in place to discuss options for that type of scenario in the coming weeks. We will continue to work with stakeholders to maintain the right balance for Lake Okeechobee water management.”

Draft EA and proposed FONSI are currently available for a 15-day public and agency review on the Jacksonville District website at (Look in the folder for “multiple counties” to find the documents for review. Comments will be accepted in writing by mail at Jacksonville District Corps of Engineers, 701 San Marco Boulevard, Jacksonville, FL 32207-8175.)

Comments will also be accepted by email at through Aug. 21.