In early May 2016, an algae bloom grew to cover 85 square kilometers (33 square miles) of Florida’s Lake Okeechobee. The conditions that gave rise to the bloom have been blamed for affecting water quality downstream all the way to the Atlantic Ocean.

Why Florida’s toxic algae crisis is worse than people realize

Water data reveal how a devastating agricultural legacy, aggravated by decades of political failure and now climate change, has thwarted quests for solutions.
In early May 2016, an algae bloom grew to cover 85 square kilometers (33 square miles) of Florida’s Lake Okeechobee. The conditions that gave rise to the bloom have been blamed for affecting water quality downstream all the way to the Atlantic Ocean. [ NASA ]
Water data reveal how a devastating agricultural legacy, aggravated by decades of political failure and now climate change, has thwarted quests for solutions.
Published June 10, 2020

Florida has struggled for almost two decades to control the blue-green algae that periodically carpets Lake Okeechobee and threatens tourism on the coast. The blooms in the state’s largest freshwater lake are stimulated by phosphorus, a key ingredient in the fertilizer used on nearby ranches and farms.

The state has passed laws and spent hundreds of millions of dollars on water treatment projects to reduce the phosphorus flowing into the lake. But it continues unabated, according to a review of state water-monitoring data by and the Investigative Reporting Workshop.

The amount of phosphorus entering Lake Okeechobee today is roughly the same as it was in 2001, when the state ordered what would have amounted to a 70 percent reduction by 2015.

Agricultural runoff is the source of three-quarters of it, according to state data.

In March, the legislature tackled the algae problem again when it passed the Clean Waterways Act of 2020.

But the new law, like the 2001 law, doesn’t require growers to monitor or reduce the phosphorus running off their land, even though a court-ordered regulatory system south of the lake has been a big success. Instead, the new law continues what is effectively a voluntary program – one so forgiving that no rancher or farmer has been sanctioned for water-quality violations.

Florida’s phosphorus problem is so acute that it has created a divide between the agriculture industry in the center of the state and tourism hubs on the Atlantic Ocean and Gulf of Mexico. Phosphorus from Lake Okeechobee reaches the coasts through rivers and man-made canals, nourishing a smelly, guacamole-like algal goop that drives away tourists and can be toxic to humans. Coastal residents increasingly blame the agriculture industry for the mess. Farmers and ranchers insist they’re not to blame and argue that costly water regulations would doom their way of life.

Reaching a solution will be politically challenging. Many experts say tougher monitoring and regulation of agricultural runoff is necessary, but the agriculture industry has resisted regulation.

“Solving this problem requires proactive efforts to monitor, to regulate and to enforce,” said Keith Rizzardi of St. Thomas University School of Law in Miami Gardens. Rizzardi also served as an attorney for the South Florida Water Management District and the U.S. Department of Justice Division of Environmental and Natural Resources.

But conservation biologist and ecologist Hilary Swain warns that regulations, if not carefully thought out, could force ranchers off the land and encourage more intensive forms of farming or development.

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“None of this is cheap,” said Swain, director of Archbold Research Station, near Lake Okeechobee. “None of it is easy, and all of it’s going to, unfortunately, take quite a long time. But all of it is worth doing and all of it’s worth doing now because our problems are only going to get worse. We’re only digging ourselves a deeper hole down the road if we don’t address this.”

• • •


One of the most vexing challenges posed by phosphorus is that it forms a strong chemical bond with soil and only a small portion is released at any given time, usually with heavy rainfall. It could be decades or even centuries before all the phosphorus in the agricultural basin washes into Lake Okeechobee.

The bottom of the lake, which was sandy for thousands of years, is blanketed with millions of tons of black muck containing an estimated 50,000 metric tons of phosphorus. Nobody knows how to remove or neutralize it.

People still flock to the lake to fish, but the tall grass and abundant waterfowl bely the dark transformation taking place beneath its surface. Algal blooms kill aquatic plants by blocking sunlight. Their decay then depletes oxygen in the water, which kills aquatic animals. The lake’s once-clear water is almost opaque.

Rising temperatures associated with climate change will likely exacerbate the problem, because algae thrive in heat. Two weather stations near the lake registered eight of their 10 warmest summers in the past decade. Annual temperatures have risen 2.2˚F since 1970 at one station and 3.3˚F since 1953 at the other, according to meteorologist Jonathan Erdman.

A 2016 algal bloom covered 5 percent of the lake’s surface. Two years later, 90 percent of the surface was covered, forcing then-Gov. Rick Scott to declare a state of emergency in seven hard-hit counties.

Gov. Ron DeSantis made dealing with the algae crisis a key focus of his gubernatorial campaign.

One of his first acts was to fire the entire board of the South Florida Water Management District, which is charged with managing and protecting the water of 16 South Florida counties. Over the years, it had developed a reputation for prioritizing agricultural interests. That changed with DeSantis’ new appointments, some of whom had been clean-water activists.

DeSantis also formed two task forces to recommend legislation. States are responsible for dealing with farm runoff because the federal Clean Water Act exempts agriculture from regulations that apply to commercial, industrial and residential property.

But neither the task force recommendations nor the new law passed by the Florida legislature set a deadline for reducing phosphorus. And there is still no system in place to monitor or enforce pollution limits on farm runoff.

Supporters of the Clean Waterways Act, including the Florida Agriculture Coalition, say the existing regulatory system has improved the quality of farm runoff over the years and that requirements in the new law will make farm runoff even cleaner.

“We’re confident these measures will make a difference,” Nancy Stephens, chair of the Florida Agriculture Coalition, said in a written statement. She added that many local farmers had introduced “cutting-edge technologies to capture, store and restore water for the benefit of their broader region.”

• • •
Matt Pearce, owner of Pearce Cattle Company in Okeechobee, Florida
Matt Pearce, owner of Pearce Cattle Company in Okeechobee, Florida [ Zak Bennett for The Weather Channel ]


While Florida is better known for its oranges and sugarcane, about half its agricultural land is devoted to cattle ranching. Last year, the state had close to a million beef cows and more than 100,000 milk cows, ranking it 13th in the nation.

The heart of the cattle industry lies in the Kissimmee River basin, which serves as the headwaters of the Everglades. The basin stretches from just south of Orlando down to Lake Okeechobee, about 95 miles. The Kissimmee River is the lake’s largest tributary and accounts for most of the phosphorus it receives.

[ The Weather Channel and Investigative Reporting Workshop ]

Ranchers in the basin are proud of their heritage.

Next year, they’ll celebrate the 500th year since Ponce de Leon landed in southwest Florida in a failed attempt to begin a colony. He departed after being mortally wounded by a Calusa Indian warrior, but the cows and horses he brought with him stayed and thrived in the wild.

Ranchers say they’re being falsely blamed for the phosphorus problem.

"The perception is that we’re dumping fertilizer in the Kissimmee River and that’s going to the lake and that’s causing blue-green algae,” said Matt Pearce, head of the Okeechobee-based Pearce Cattle Company. “I’ll tell anybody who will listen, that’s wrong. There’s nobody up the Kissimmee River that’s fertilizing as much as” the public thinks.

Like many central Florida cattlemen, Pearce maintains herds of beef cattle primarily for the calves they produce, which he sells to out-of-state feedlots.

The ranchlands serve as a habitat for many rare or endangered species. Cattle graze in large pastures that are often delineated only by stands of live oaks, cabbage palms and palmetto. Bald Eagles live here. So does the Crested Caracara, a falcon-like bird whose population is declining because of habitat loss. Black bears and panthers use the ranchlands as a corridor.

From the end of World War II until the 1980s, ranchers applied large amounts of fertilizer to make this grassland more productive. Pearce says that if some farmers applied too much fertilizer during that era, they were only doing what they were told.

“That was the recommendation from the University of Florida,” he said. “You clear this pasture, and you plant these productive grasses, and you apply this amount of fertilizer. We had to feed the world's population, or the U.S. population, and you were only going to do it with a more productive landscape.”

That recommendation changed when scientists began understanding the connection between phosphorus and algal blooms. Today, pastures that were heavily fertilized during that period still have high accumulations of phosphorus in the soil.

Pearce says he fertilizes only 5 percent of the 12,000 acres he operates in any given year – roughly the same amount his father and grandfather did.

Cattlemen cite two other reasons for the basin’s high phosphorus levels.

They say the area is naturally high in phosphorus. Indeed, some of the nation’s richest deposits of phosphorus are mined in Bone Valley, just west of the Kissimmee River basin, where the remains of prehistoric sea animals accumulated while the basin was underwater for millions of years.

But the Bone Valley deposits don’t extend into the basin, and groundwater in the valley drains west into the Gulf of Mexico.

“For them to argue that the high phosphorus content is coming from the Bone Valley is incorrect,” said Thomas Scott, a geologist now retired from the Florida Geological Survey. “We're looking at sediments in the Kissimmee River basin that have a very minor amount of phosphorus.”

Ranchers also blame the phosphorus on population growth.

But land-use analyses and state water-monitoring data reviewed by and the Investigative Reporting Workshop show that between 73 percent and 87 percent of the phosphorus going into the lake comes from agricultural lands rather than urban runoff, septic tanks or other sources.

• • •
Cattle walk and eat at Archbold Biological Station’s Buck Island Ranch in December 2019 in Venus, Florida.
Cattle walk and eat at Archbold Biological Station’s Buck Island Ranch in December 2019 in Venus, Florida. [ Zak Bennett for The Weather Channel ]


Under the new legislation, ranchers and farmers outside the Everglades Agricultural Area are basically guided by the 2001 law. They’re required only to say they’ll abide by best management practices, such as rotational grazing, digging ditches and putting up fences to keep cattle out of waterways.

The Agriculture Department conducts site visits, but the agency has 25 inspectors for 11,000 enrolled farms, so farms can go years without a visit. No water testing occurs. Those who don’t abide by their promises can be referred to the Department of Environmental Protection for investigation and enforcement. But no such referral has been made and the state has not sanctioned any producer under the program.

Perhaps nobody understands the tricky tension between the need for phosphorus in food production and its adverse impacts downstream than Swain, the Archbold Biological Station director. The 8,800-acre preserve was established in 1941 primarily to study endangered species. In 1988, it gained access to neighboring Buck Island Ranch, a 10,300-acre working cattle ranch that now doubles as a living laboratory.

The ranch and research station have a mix of “native” pastures that have never been fertilized and “improved” pastures that were fertilized until 1987. When researchers analyzed the runoff, they found something shocking. Even though phosphorus hasn’t been applied to the improved pastures since Ronald Reagan was president, their runoff had five to seven times as much phosphorus as runoff from the native pastures – and the pastures were lush enough to support roughly 3,000 head of cattle.

“Unfortunately, phosphorus binds in soils in very complicated ways,” Swain said. “Concentrations are not changing on our ranch. We know that by holding water back we can reduce the flow, and that’s where there’s progress.”

The heaviest concentrations are in an area close to the lake that once hosted dairy farms. Most of them moved in the 1990s, but the phosphorus levels there – although improved – are among the highest in the basin.

The basin’s phosphorus buildup is estimated at 190,000 metric tons. For the past five decades, on average, 450-500 metric tons a year has drained into Lake Okeechobee. If that rate continues, phosphorus from the basin could, theoretically, be draining into the lake for the next 300 to 400 years, said Del Bottcher, president of Gainesville, Florida-based Soil and Water Engineering Technology, a private firm.

[ The Weather Channel and Investigative Reporting Workshop ]

To slow the flow, Florida has spent hundreds of millions of dollars to restore the natural serpentine course of the Kissimmee River. It also created holding areas for water, so some of the phosphorus can settle into the soil before the water moves south to the lake. Some $50 million has gone to farmers and ranchers to help them improve their water management.

As impressive as that sounds, billions more is needed.

Bottcher estimates that projects north of the lake ultimately will require a $6 billion capital investment and $600 million a year, perhaps for decades. At that rate, it could take a century to reduce the phosphorus in Lake Okeechobee to the target set back in 2001.

“It took us a hundred years to impact the watershed,” he said. “We should realize that it will likely take perhaps a similar time to fully recover.”

This story is a collaboration of the Investigative Reporting Workshop and The Weather Channel. Stern reported this story for The Weather Channel and the Investigative Reporting Workshop. Kornfield reported this story for the Investigative Reporting Workshop.

Additional credits:

• Photography by Zak Bennet, The Weather Channel, and Hadley Chittum, Investigative Reporting Workshop

• Photo Editor: Nicole Bonaoccorso, The Weather Channel.

• Edited by Susan White and Lynne Perri, Investigative Reporting Workshop; Patty Cox and Keith Epstein, The Weather Channel