Corps trying to lower Lake Okeechobee this year only; lake level below 11 ft. needed to regrow vegetation

Posted 3/24/19

OKEECHOBEE -- The U.S. Army Corps of Engineers efforts to lower Lake Okeechobee this year is designed to benefit the lake’s ecology and improve the resiliency of the St. Lucie and Caloosahatchee …

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Corps trying to lower Lake Okeechobee this year only; lake level below 11 ft. needed to regrow vegetation

OKEECHOBEE -- The U.S. Army Corps of Engineers efforts to lower Lake Okeechobee this year is designed to benefit the lake’s ecology and improve the resiliency of the St. Lucie and Caloosahatchee estuaries, according to a report given by Lt. Col. Jennifer Reynolds at the March 22 meeting of County Coalition for Responsible Management of Lake Okeechobee, St. Lucie and Caloosahatchee Estuaries and the Lake Worth Lagoon. The meeting was held in the Historic Okeechobee County Courthouse.

She said the corps is using the flexibility available under the Lake Okeechobee Regulation Schedule to try to lower the lake this year only. The science does not support lowering the lake to 10.5 ft. every year, she added.

Over the past three years, the Lake Okeechobee watershed has experienced weather extremes which have resulted in ecological damage to the lake, she explained. As a result, the lake has lost most of the submerged aquatic vegetation which helps clean the water, and also provides habitat for fish and wildlife.

“What we’ve seen recently are real extremes,” said Lt. Col. Reynolds.

In 2016, the lake had about 33,000 acres of aquatic vegetation, she said. Just before Hurricane Irma hit, that had been reduced to 20,000 acres.

After Hurricane Irma, there is only about 5,000 acres of aquatic vegetation left, she explained.

Due to Hurricane Irma and other weather extremes in recent years, “an enormous amount of nutrients” came into the lake, she said, noting that 95 to 97 percent of that nutrient load came from north of the lake. Water flowing into the lake starts just south of Orlando.

The loss of aquatic vegetation has reduced the ability of the lake to clean that water, she continued.

“These extremes have caused the lake to suffer significant ecological damage,” Lt. Col. Reynolds said. That ecological damage has spread to the estuaries on the east and west coasts and to the Stormwater Treatment Areas (STAs) south of the lake.

She said pushing large volumes of water from the lake through the STAs can overwhelm the ability of the STAs to clean the water.

Due to the ecological damage from the extreme weather events in recent years, the corps decided to do something different this year, Lt. Col. Reynolds explained.

“We’re really trying to focus on the science and engineering and doing what we can do,” she continued, to improve the ecological health of the lake, create some resiliency in the estuaries and move as much fresh, clean water as possible to Everglades National Park, the Refuge and Florida Bay.

She said they are trying to lower the lake levels about once every six to 10 years because it is beneficial to the lake vegetation, allows sunlight to get to the lake bottom and allows for controlled burns to burn off the dead vegetation around the edges of the lake, reducing the biomass.

“This is not something we would want to do every year,” she said.

“We have not been directed to lower the lake to 10.5 ft.”

She said it would be beneficial to get the lake to 11 or 11.5 ft. for less than 90 days, to allow controlled burning.

Controlled burns are conducted by Florida Fish and Wildlife Commission (FWC) in partnership with the South Florida Water Management District and the corps.

“I do know that smoke is one of the concerns for the permitting,” she said. So far, about 8,000 acres have been burned this year, she added.

Hendry County Commissioner Karson Turner said that while smoke is a nuisance for those who have to deal with it, but the benefits of controlled burns outweigh the smoke issues.

“Weighing the pros and cons, we know it is uncomfortable, but let’s light it up,” he said.

Lt. Col. Reynolds said lowering the lake now means we will go into the wet season with a lower lake level, which reduces the risk of harmful freshwater releases to the coastal estuaries.

“While we wouldn’t want to do that every year, the forecast this year indicates there won’t be a drought,” she said.

“We are lowering the lake within the operational band predominantly for the health of the lake so that we can regrow some of the aquatic vegetation and take advantage of doing some controlled burns,” she said.

The scientific information indicates 12 ft. to 15 ft. or 12.5 ft. to 15.5 ft. is the most ecologically beneficial for the lake, she said. However, the science also tells us that once every 6 to 10 years, the lake should go below 11 ft. to allow the natural vegetation to regrow, she said.

“It is not something that would be healthy to do on a regular basis,” she said.

The lake level has gone over 16 ft., in six of the past seven years, said Dr. Paul Gray of Florida Audubon. “Sixteen feet is when things start going bad.

“When Irma came in, we were already at 17 ft.,” he said. The years of high water have caused the lake to lose about 60 square miles of vegetation, he said.

Under normal conditions, 12 ft. is low enough for the grass to grow, he continued. But there are not enough plants left alive in the lake, and due to the turbidity left by Hurricane Irma, with water levels at 12 ft., sunlight doesn’t reach the bottom.

With so much of the aquatic vegetation lost, “we’ve got to get sunlight all the way to the bottom so seeds will start growing,” Dr. Gray said.

“We have had this happen before,” he said.

“The plants can grow back. They will grow back, but we have to have that drought.”

“We have to get lake down to 11 ft. to get light to the bottom. If it’s successful, it will regrow the plants,” he said.

“Whether they are making the right call now, nobody knows,” said Dr. Gray. The corps might release water to the estuaries and never get the lake low enough for the plants to grow. Or the predictions could be wrong, and South Florida could wind up in a real drought.

“The corps is doing everything they can to help us restore this lake,” he said. “We applaud them for going above and beyond the call of duty and help us to get the lake back on track.”