El Niño rains to blame for Lake Okeechobee water sent to the St. Lucie River, Stuart

Katie Delk, Treasure Coast Newspapers
Updated ·7 min read
1

Lake Okeechobee water will start pouring into the St. Lucie River on Saturday.

According to a Feb. 14 Army Corps press release, an estimated:

  • 1.2 billion gallons per day of lake water will pour into the St. Lucie River through the St. Lucie Lock and Dam in west Stuart

  • 2.6 billion gallons per day into the Caloosahatchee River through the Julian Keen Lock and Dam in Moore Haven

  • 323 million gallons per day into the Lake Worth Lagoon through the C-51 canal, according to the Army Corps of Engineers press release.

The discharges will continue for an unknown number of days, but the Corps will assess the lake and may lower releases by April 1, Col. James Booth said in a Feb. 16 meeting. Moving water out of Lake Okeechobee is controlled largely by the Army Corps of Engineers.

Why is Lake O being lowered?

The releases are occurring after high levels of rainfall due to El Niño, the Corps said. The level of Lake Okeechobee on Feb. 15 the past six years was:

The Army Corps wants to lower the lake level in time for summer rains. June 1 is the start of the hurricane and rainy seasons. The Corps is trying to create more storage in the lake for storm runoff and "flood risk management," Booth said.

“Releases are being made now to lower the lake level as much as possible before the wet season and to avoid high-volume releases, if possible, during oyster-spawning season or peak algal-bloom months," the Corps said in the press release.

The high lake elevation damages its ecology, Booth added. Once above 15 1/2 feet, the lake is flooded, blocking sunlight and smothering grasses, Audubon Florida biologist Paul Gray told TCPalm.

"Any reduction in water levels will be a relief and help the lake," Booth said. "Our charge is to balance the needs of all systems and stakeholders."

How are the discharges averaged?

What are pulse releases?

One of the main phrases in the Army Corps press release is: "an average of 4,000 cubic feet per second (cfs) at Julian Keen Jr. Lock and Dam (S-77), 1,800 cfs at St. Lucie Lock and Dam (S-80) and up to 500 cfs to the Lake Worth Lagoon through the C-51 canal."

The average is calculated over two weeks. So the discharges will begin at a flow rate higher than 1,800 cfs — at 3,200 cfs the first day, going up to 3,600 cfs the second day and so on until the final four days of the two week period is zero cfs. It's all explained in the chart below.

Discharges from Lake Okeechobee to the St. Lucie River and Caloosahatchee River will begin Feb. 17, 2024.
Discharges from Lake Okeechobee to the St. Lucie River and Caloosahatchee River will begin Feb. 17, 2024.

Is there a risk of harmful algae blooms?

Unlike in the summer, winter discharges pose little risk of toxic algae blooms fouling local waters. The Department of Environmental Protection detected no cyanobacteria in the lake as of Feb. 5 — specifically microcystis aeruginosa, often called "blue-green algae."

Is the Army Corps using the C-44 Reservoir?

The Army Corps is still designing relief wells for the C-44 Reservoir "seepage" and hasn't answered how many wells will be constructed, how deep they will be, where they will be located and how much they will cost. The $339 million reservoir is designed to capture and clean canal water — some Lake O discharges and 65% of the stormwater runoff. The water is moved by gravity into a 2-mile-long canal that runs perpendicular to Citrus Boulevard to pumps which load it into the 2-mile by 3-mile long reservoir.

As of Feb. 16, the reservoir was at about 5 feet, which is about a third of its maximum capacity.

How much Lake O water flowed into the St. Lucie River in 2023?

The discharges beginning Saturday are the first Lake O discharges since an 83-day release from Jan. 22 to April 15, 2023 when 17.3 billion gallons of lake water entered the St. Lucie River, according to Army Corps data. The discharges lowered the lake by 1 foot, 10 inches. Here is a timeline of what happened last year:

  • Jan. 22: Army Corps started discharging 320 million gallons of Lake O water per day

  • Feb. 22: DOH issued a health alert because a water sample tested positive for toxic algae

  • Feb. 28: Army Corps suspended discharges and South Florida Water Management District used a peroxide-based algicide to reduce the toxin's concentration

  • March 2: Army Corps resumed discharges at the same rate of 320 million gallons per day

  • March 5: Army Corps suspended discharges for a second time after Port Mayaca Lock & Dam workers observed toxic algae in the water

  • March 10: Army Corps resumed discharges at an increased rate of 323 million gallons per day.

  • April 15: Army Corps stopped discharges because of toxic algae

Is LOSOM being applied to this discharge event?

The St. Lucie River got no Lake O water during the 2023 summer rainy season because the Army Corps said it was managing the lake level as if the new Lake Okeechobee System Operating Manual (LOSOM) was in effect, Lt. Col. Todd Polk told TCPalm in July 2023.

Clean-water advocates are eager for the Army Corps to complete and officially implement LOSOM. Under LOSOM, the St. Lucie River would receive zero discharges. The Corps said in its press release that is using the Lake Okeechobee Regulation Schedule 2008 (LORS08) designed and implemented 16 years ago.

LOSOM is expected to be completed later this year, Maj. Cory Bell told the Rivers Coalition in Stuart on Jan. 18. The Corps is still evaluating a biological opinion issued in September by NOAA-National Marine Fisheries Service.

"The St. Lucie River would not get any lake water until the lake rose above about 16.5 feet," said Eve Samples, executive director of Friends of the Everglades in Stuart.

What are Lake Okeechobee discharges? Risks include water pollution and toxic algae blooms

Lake O management plan delays: Army Corps began LOSOM 5 years ago. What is taking so long?

Can Lake Okeechobee discharges harm humans and pets?

Here’s why discharges are a danger to the environment:

  • Lake O is polluted with rainfall runoff from as far north as Orlando. The contaminants, mostly nitrogen and phosphorus from development and agriculture, feed algae blooms.

  • Blooms block sunlight and suck oxygen from the water, which kills seagrass, the main food of starving manatees.

  • Flooding the brackish St. Lucie estuary with freshwater for an extended period kills oysters. The estuary needs these filter feeders to clean up to 50 gallons of water per day per oyster.

  • Silt carried downstream can smother seagrass, nearshore coral and offshore worm rock reefs.

  • They can kill fish. Over 25 species developed lesions and open, bleeding sores in 1998. Snook also died because the freshwater stripped their protective mucus coating.

  • In 2018, it was confirmed by a veterinarian that a Stuart dog, Finn, died from exposure to harmful algae blooms in the St. Lucie River.

“Historically, discharges from Lake Okeechobee have led to significant environmental consequences to the St. Lucie River and Indian River Lagoon, including harmful algal blooms, seagrass die-offs and the destabilization of estuarine ecosystems and our coastal waters,” said Mark Perry, Executive Director of Florida Oceanographic Society in Stuart.

Katie Delk is an environmental reporter for TCPalm. Contact her at katie.delk@tcpalm.com or 772-408-5301. Check for updates at @katie_delk.

This article originally appeared on Treasure Coast Newspapers: Army Corps blames El Niño on Lake O discharges to St. Lucie in Stuart