Lake Okeechobee level rising, discharges continue to St. Lucie, Caloosahatchee rivers

With Lake Okeechobee rising in the aftermath of Tropical Storm Eta, discharges to the St. Lucie and Caloosahatchee rivers will continue for an undetermined amount of time, the Army Corps of Engineers announced Friday.

Lake O's elevation above sea level, which was 16 feet, 2½ inches when the discharges started Oct. 14, dropped as low as 16 feet, 3/4 inches last Saturday. Then Eta hit, and it's risen 4½ inches to 16 feet, 5⅜ inches Friday morning.

"It's likely we'll continue high-volume releases into the future," said Col. Andrew Kelly, Corps commander for Florida. "There's simply nowhere else for the water to go."

More: Army Corps starts Lake Okeechobee discharges to St. Lucie

Eta dumped lots of rain south of Lake O, making it impossible for the Corps and the South Florida Water Management District to send water to storage areas there.

It could take "two to three months to get back to normal, to get water flows south back to what they should be," Kelly said. That doesn't mean discharges could last another two to three months, but Kelly would not say how much longer they'll last.

Lower Lake O next year

The Corps will work to drop the lake level lower than normal during the upcoming winter and spring dry season to reduce the likelihood of discharges next summer, Kelly said.

He didn't say how low he wanted the lake to go. The Corps usually tries to bring the lake down to 15 feet, 6 inches at the end of the dry season, but "15 feet is not good for anybody," Kelly said, hinting the desired level would be lower.

In 2019, the Corps allowed Lake O's elevation to drop below 11 feet, primarily to allow underwater grasses that had died from years of too-deep water to recover. The move also kept Lake Okeechobee discharges at bay that year, although water users south of the lake said the Corps had created a "man-made drought."

More: 'Crystal clear' water shows lowering Lake O worked, congressman says

There's "no concern for water supply" this year, Kelly said. "Everybody has more water than they want or need."

Lowering the lake would reduce the possibility of discharges in the mid-summer when blooms of cyanobacteria, more commonly called blue-green algae, Kelly said.

No algae threat

There appears to be no threat of blue-green algae blooms in the St. Lucie during the current round of discharges. 

A satellite image taken Thursday showed little or no blue-green algae on Lake O, although some areas were obscured by clouds.

No algae was seen by Florida Department of Environmental Protection crews Thursday at the Port Mayaca Lock and Dam, where lake water is discharged toward the St. Lucie, or at the Moore Haven Lock and Dam, where lake water is discharged toward the Caloosahatchee.

More:Algae bloom toxins in air can linger 2 hours, travel 10 miles

Tests for toxins in water samples taken at both sides were pending Friday morning.

No lake water was discharged toward the St. Lucie on Monday, Tuesday and Wednesday, but the estuary was bombarded with nearly 5 billion gallons of water through the St. Lucie Lock and Dam on those days.

The reason: Heavy rain from Eta that fell on western Martin County drained into the C-44 Canal, which connects the lake and the St. Lucie; and the Corps had to let that water drain into the estuary before more water could be discharged from Lake O.

Lake O discharges to the St. Lucie resumed Thursday, but at a diminished rate of 380 million gallons while nearly 1.5 billion gallons of rainfall runoff into the C-44 Canal poured into the river.

Lake Okeechobee discharges

Since discharges began, about:

• 27.1 billion gallons of water has poured through the St. Lucie Lock and Dam into the St. Lucie River, enough to cover the city of Stuart with 16 feet of water
• 15 billion gallons of that has been from Lake O
• 12.1 billion gallons has been from the C-44 Canal watershed in western Martin County.

A report issued Thursday by the Florida Oceanographic Society in Stuart showed improved water quality in sections of the St. Lucie River estuary and the adjacent Indian River Lagoon not impacted by the discharges, such as the river's North Fork and the lagoon north and south of the St. Lucie Inlet. 

Areas impacted by discharges — the South Fork below the St. Lucie Lock and Dam and the main river channel through Stuart to near the inlet — had conditions the report called "destructive" to the environment. 

More: Florida Oceanographic Society water quality reports

The conditions are taking a toll on the estuary's oysters, said Loraé T. Simpson, director of scientific research and conservation at the Florida Oceanographic Society in Stuart.

"This is the first month (since starting to sample in May) that we have seen high mortality in the baby oysters," Simpson said in an email. "On average, spat mortality was 20% whereas this month it was 42%." 

With significantly high tides known as "king tides" forecast for the Treasure Coast this weekend, releases to the St. Lucie will "be managed on an hour-by-hour, minute-by-minute basis" to reduce the threat of flooding in low-lying areas, particularly along the South Fork, Kelly said.

More: Lake O discharges, king tides increase flooding risks

Cutting back on discharges as the high tides come in will help flush the estuary with salty water, which could help oysters survive.

Tyler Treadway is an environment reporter who specializes in issues facing the Indian River Lagoon. Support his work on TCPalm.com.  Contact him at 772-221-4219 and tyler.treadway@tcpalm.com.