It’s Toxic Slime Time on Florida’s Lake Okeechobee

For thousands of years, Lake Okeechobee pumped life into Florida’s swampy interior. Summer rains swelled the shallow inland sea, creating seasonal overflows that sustained the Everglades and its alligators, panthers, spoonbills and snail kites.

But a vast re-engineering over the past century has transformed Okeechobee into something life-threatening as much as life-giving. Toxic algal blooms now regularly infest much of its 730-square-mile surface during the summer, producing fumes and waterborne poisons potent enough to kill pets that splash in the contaminated waters, or send their owners to the doctor from inhaling the toxins.

The Okeechobee mess, caused mainly by phosphorus-based agricultural fertilizers, festered out of the public consciousness for decades. But in recent summers the problem has become more dire. Climate change is making storms and rainfall more intense and less predictable, and last fall Hurricane Ian stirred up so much phosphorus that this summer is expected to be particularly bad.

Things get further complicated when lake levels climb so high that contaminated water must be released into canals — toward coastal cities like Fort Myers and Stuart — to protect the structural integrity of the 143-mile-long dike holding back the lake.

The coming weeks will offer a serious test.

Rainy season is just starting, but by late June the lake’s level was roughly two feet higher than the United States Army Corps of Engineers would like. While that’s a few feet below the dike’s potential danger zone, history has shown that Okeechobee can swell by that much in less than a month.

Adding to the worry: More than half the lake is already suffering algal blooms. And the algae season has months to go.

This has people downstream bracing for another summer of sludge. “We’re looking at a bullet in the chamber here,” said Eve Samples, executive director of the conservation group Friends of the Everglades.

The state and the Army Corps of Engineers are trying to reduce the toxic flows to the coasts with a controversial re-engineering plan that has been decades in the making, including building a new lake from scratch to contain and decontaminate Okeechobee’s discharges.

Yet critics worry it’s still not enough, particularly as the world keeps warming. Scientists say hurricanes are getting not only more powerful because of climate change, but also wetter. Ian last year most likely dropped 10 percent more rain than would have been expected in a world without warming, researchers have said.

Star Robinson, 55, grew up playing in and around Okeechobee. But in recent years her relationship with the lake has soured. On a morning jog in the city of Pahokee a few weeks ago, she kept at least 100 yards from the shoreline, and with good reason. Any closer and she risked choking on the lake’s lung-burning fumes.

The only activity near the water’s edge? A cluster of buzzards. “They just love the smell of death and decay,” she said.

The vapors come from rotting mats of a type of toxic algae — technically a cyanobacteria — that thrives in Okeechobee’s tea-warm water and feasts on rising levels of atmospheric carbon dioxide and the phosphorus-rich fertilizer and manure that wash off cropland and into the lake.

The immediate dangers include lung infections and gastrointestinal distress. There are also concerns that long-term exposure could lead to organ damage and the risk of certain neurological disorders.

“This has become almost like a permanent condition,” said Gil Smart, executive director of VoteWater, a nonpartisan group pushing for a more ambitious fix. “It’s like you have spring, you have summer, and you have algae bloom season,” he said. “Like clockwork.”

Similar outbreaks have struck lakes elsewhere, including Lake Champlain, Lake Erie and Lake Tahoe. But Okeechobee is different. It is warm, flat and shallow as a backyard pool — making it more like a supersize petri dish than the wellspring of the Everglades.

Ms. Robinson, the jogger, said she knows how to fix a lake that has “gone to hell.”

“Stop the polluting,” she said. “That’s it. That’s the solution.”

It’s not likely to happen anytime soon.

The crisis was borne of decisions starting a century ago to tame the lake by holding back its seasonal overflows in order to drain swamps, creating rich farmland. That has transformed southern Florida into one of the most important sugar-cane-producing regions in the world.

It came at a heavy cost.

Disaster struck in 1926, when a hurricane collapsed part of the dike, drowning hundreds of people. The dike was patched, but two years later it happened again, this time killing thousands.

By the 1960s the Army Corps of Engineers proclaimed it had finally controlled the lake with what is now called the Herbert Hoover Dike, a mound of sand, rock and seashells rising a couple of stories above the table-flat landscape.

Since the dike severed the lake’s natural flow into the Everglades, the corps now operates canals to carry much of the outflows eastward to the city of Stuart on the Atlantic coast, and west to Fort Myers on the Gulf Coast.

For decades, the canals carried away lake water. Then, the algae came.

About a decade ago, Okeechobee’s outflows began triggering intense downstream algae outbreaks as green as anything Sherwin-Williams might concoct. The coastal impact was particularly bad in 2013, 2016 and 2018, causing beach closures, business shutdowns and even some residential evacuations. (This is different from red tide, another type of toxic algal bloom.)

The releases were necessary because an old fear had returned. Engineers realized a few decades ago that Hoover Dike, notoriously leaky, was in danger of collapsing once again if water levels climbed too high. Today, tens of thousands of people live in Okeechobee’s flood path.

An 18-year, $1.5 billion dike-fortification project was completed last January. That probably means fewer algae releases toward Fort Myers and Stuart.

But nobody thinks Okeechobee’s problems are solved. Not only does climate change increase the risk of heavier rain in the future, but water can already flow into Okeechobee about six times faster than the canals can carry it away.

That’s why high lake levels so early in the rainy season are worrisome. In the mid-2000s, for example, a particularly rainy period raised Okeechobee’s level by about four feet in just a month.

The Army Corps of Engineers said it is doing its best to protect the ecological health of the peninsula, the people who live downstream and the farmers. “While I can’t promise that there won’t be high releases later this year due to the inherent uncertainty of Mother Nature, we will do our best to avoid them, if possible,” Col. James Booth of the corps said in June.

This winter the corps moved ahead with a Manhattan-size reservoir and wetlands complex. A decade or so from now, a 37-foot-high wall — holding back the new lake — will tower over sugar cane country.

The idea is that the reservoir will capture at least some of Okeechobee’s toxic outflows instead of sending them to the coasts. The 10,500-acre reservoir and the recently completed 6,500-acre artificial wetlands, designed to absorb phosphorus, are the centerpiece of a growing system of canals, gates, pumps and engineered wetlands built to clean the outflows so they can once again drift south into the Everglades as well as provide drinking water to booming South Florida. The two projects will cost roughly $4 billion.

During a recent visit to the site, Tim Harper, an engineer with the South Florida Water Management District, parked his pickup and asked his passengers to take in the endless sea of sugar cane that will one day be lake bottom. “Now, imagine 23 feet of water above you,” he said, “essentially for as far as the eye can see.”

It’s a difficult picture to conjure.

Equally challenging to grasp is the idea that the whole new lake, as big as it sounds, will fill to capacity if only six inches of Lake Okeechobee is sent its way.

An earlier proposal for a 60,000-acre system was scuttled when agricultural operators, primarily sugar cane growers, objected. Obtaining the land through eminent domain wasn’t an option after the Florida Legislature in 2017 prohibited allowing the state to force a sale.

Scaling back the reservoir has required drastically increasing its depth. The corps says it will still be big and stout enough to trap and treat a significant amount of the contaminated waters.

The project has the support of President Biden and Gov. Ron DeSantis, a 2024 Republican presidential hopeful.

Many conservationists welcomed the decision to build a smaller reservoir as a major step in the right direction. “No project will play a bigger role in reducing algae-causing discharges from Lake Okeechobee,” said the chief executive of the Everglades Foundation, Eric Eikenberg.

Others are skeptical.

Bill Mitsch, retired director of the Everglades Wetland Research Park at Florida Gulf Coast University, sees the project as too small. He worries it may even result in harm to the Everglades if the phosphorus-absorbing wetlands don’t work as well as predicted. “There is just not enough capacity,” he said.

Ms. Samples, of the Friends of the Everglades, shares that concern. “Florida has this century-long history of trying to out-engineer Mother Nature and having it backfire, and it really feels like we’re repeating the mistakes of our past,” she said.

June 11 was a Sunday — a boat day — near Stuart on the coast. A flotilla of Floridians landed on a sandbank a couple of miles offshore and soaked up sun and drinks in thigh-deep waters.

Some talked about how thrilled they were to see native seagrass making a comeback since it was ravaged five summers ago by Okeechobee toxic outflows. The grasses provide fish habitat as well as essential food for beloved manatees, which are in such a desperate condition that government crews have taken to feeding them romaine lettuce.

Stefani Hughes, a real estate agent, remembered 2018’s outflows for the damage not just to the ecology, but to the economy as well. “I personally lost a $1 million sale watching the green plume come in,” she said.

Conservationists say state rules to control the flow of phosphorus from agricultural lands, by far the largest source of the pollutant, have long been poorly enforced. Yet even if fertilizer runoff stopped tomorrow, the algae threat would persist for decades or more because there is already so much phosphorus tied up in cropland soils and lake sediment.

This is one reason the path forward has included building the new reservoir and investing in phosphorus-catching artificial wetlands.

But for the moment, people like Mr. Smart of VoteWater aren’t worried about the next decade. They’re worried about the next several weeks. “Everybody keeps their fingers crossed that we won’t have a rainy summer, and that the toxins that are in the lake, stay in the lake,” he said.