Get ready for Lake Okeechobee discharges to the St. Lucie and Caloosahatchee rivers.
Discharges could start as soon as a week from now, Col. Andrew Kelly, Army Corps of Engineers commander for Florida, said in a call-in news conference Friday, because Lake O is rising rapidly and the tropical storm season is still active.
Heavy-volume discharges that continue over several weeks or months can cause significant environmental damage, including toxic blue-green algae blooms, to both river estuaries. The blooms can cause health problems for people and animals along the rivers as well as economic hardship for water-related businesses.
More: People along St. Lucie River breathe in toxins during massive algae blooms
The Corps discharges water to the estuaries when high water levels in the lake threaten the integrity of the Herbert Hoover Dike that surrounds it. Ideally, the Corps wants the lake elevation to remain between 12 feet 6 inches at the beginning of the summer rainy season and 15 feet 6 inches as the dry season begins in late fall.
Lake Okeechobee’s elevation was 15 feet 1¼ inches Friday morning. That’s:
- 4½ inches higher than a week ago
- 1 foot, 2½ inches higher than 30 days ago
No risk ‘right now’
“There’s no risk of flooding to the population surrounding the lake right now,” Kelly said, “but it’s always about that next set of storms that could be coming.”
After Hurricane Sally’s landfall near Pensacola this week, the National Hurricane Center is tracking six systems over the Atlantic and Gulf of Mexico, including a hurricane, two tropical storms and three other disturbances.
Kelly said the storms “pose no imminent threat” to Florida but show “there’s still a lot happening” in this year’s hurricane season.
“If we get another foot in the coming month, that puts the lake over 16 feet,” Kelly said. “That is not good, especially when you factor in the possibility that a hurricane could put another 3 feet on the lake.”
Kelly said the discharges could have started this week, except the South Florida Water Management District “found some places to put some water south of the lake … that bought us some time. If we get a couple of weeks of dry weather that could buy us some more time. But we’re on a day-to-day watch right now.”
630 million gallons a day
If the Corps begins discharges to the St. Lucie River, expect the flow through the St. Lucie Lock and Dam to be about 630 million gallons day, including C-44 basin runoff, said spokesman John Campbell.
The Corps hasn’t discharged Lake O water to the St. Lucie since March 2019. But in late August the agency began sending water from the C-44 Canal through the gates at the St. Lucie Lock and Dam and into the river.
In case you missed it: Corps begins sending Lake O water to St. Lucie River
More: Keep track of water flows on Army Corps of Engineers spillway cameras
And: See all of TCPalm’s coverage of Indian River Lagoon issues
Canal water hasn’t been flowing into the St. Lucie continuously; the Corps opens and closes the gates as needed to manage the canal level.
The gates were open throughout the last week, though; and 2.4 billion gallons of water from the canal flowed into the estuary.
Water in the canal, which drains mostly farmland in western Martin County, tends to be high in fertilizer runoff that can feed blue-green algae blooms in both the lake and the estuary.
Even fertilizer-free water, in large amounts, can cause harm by lowering salinity in the estuary’s brackish water, threatening the oysters and seagrass that form the backbone of the ecosystem.
Salinity in the estuary already is low because of frequent summer rain.
Water quality in the estuary received a “C-” grade Thursday from the Florida Oceanographic Society in Stuart. The river’s South Fork near the outflow of the St. Lucie Lock and Dam earned a “D” grade because of poor salinity and fair visibility.
Caloosahatchee River estuary
The target flow for Lake O discharges to the Caloosahatchee River estuary would be about 1.6 billion gallons a day, Campbell said.
But the estuary already is getting an average of over 2.7 billion gallons a day from the river’s watershed; no water is coming from Lake Okeechobee.
The flow caused a freshwater plume in the Gulf of Mexico at San Carlos Bay near the mouth of the river at Fort Myers, according to the Sanibel-Captiva Conservation Foundation.
The reason: Too much rain. The city of Sanibel received over 10 inches of rain from Sept. 11 through Tuesday.
On Wednesday the foundation asked the Corps not to send any Lake O water to the Caloosahatchee until the flow from local runoff drops below 1.4 billion gallons a day.
After that, foundation officials said, flows should range between 500 million and 1.4 billion gallons a day to help maintain proper salinity in the estuary and fight off saltwater intrusion from the Gulf.
‘The right call’
During this year’s winter-spring dry season, as environmental groups called for lowering the lake to prevent the need for discharges, the Corps tried to keep as much water as possible in Lake O to make sure there was enough for the farmers and municipalities that depend on it.
Even with the threat of damaging discharges to the estuaries now, Kelly said Friday the Corps made the right call.
In the late spring, the Corps was looking at the possibility of a water shortage, he said.
“It was dry everywhere. At that time it was absolutely the right call to do what we did.”
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 firstname.lastname@example.org.