Florida Researchers Hope to Clean Up Polluted Waterways With Hemp
Steve Edmonds wades through a lake where he's growing hemp in attempt to suck up the excess nutrients in the water and minimize algae growth.
Photos courtesy of Steve Edmonds.

Florida Researchers Hope to Clean Up Polluted Waterways With Hemp

Based at South Florida State College, two researchers are working to develop a method of hydroponically growing hemp that can not only provide a viable crop but also clean up the state’s algae-filled waterways.

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May 12, 2020

Before its prohibition, hemp had been cultivated on fields across the U.S. for centuries—but Steve Edmonds’ vision of growing it hydroponically on polluted bodies of water might just be a first.

Edmonds has had the idea to clean up waterways using hemp since toxic blue green algae blooms severely invaded Lake Okeechobee in his home state of Florida in 2013. Now that hemp is federally legal to grow, Edmonds, a political science professor at Valencia College, has found a research partner at South Florida State College to carry out an experiment that’s been years in the making.

“I would love to restore Lake Okeechobee to the pristine, sandy-bottomed lake that it was 25 years ago,” Edmonds says. “If I could leave that to my grandchildren, then that would be wonderful.”

A Personal Mission

Lake Okeechobee, called “The Liquid Heart of Florida” by the South Florida Water Management District, helps supply more than 8 million residents with water in the southern part of the state. Algae blooms, some of which are toxic, have become a recurring threat to the state’s largest freshwater lake, which passes the deadly toxins on to connecting waterways and even the Atlantic coast. 

Edmonds recalls 2013 as a turning point, when the algae blooms in the lake were so severe that they led to what is now known as “Toxic Summer,” according to National Geographic. He worked to brainstorm ways to not get rid of the algae, but to prevent its bloom in the first place.

“We were trying to figure out what was causing the blooms, and we decided that it was the overload of nutrients in the water,” Edmonds says. 

Indeed, a 2015 study by the Harbor Branch Oceanographic Institute (HBOI) has found that high concentrations of nutrients from sewage plants and septic tanks draining into Lake Okeechobee fed the algae and contributed to its explosive growth. The top nutrient offenders, the study found, are nitrogen and phosphorus—which just happen to be two vital nutrients for hemp cultivation.

The point clicked with Edmonds, who has been a long-time cannabis advocate. “If we could grow cannabis on water, we could suck up all the nitrogen and phosphorus,” Edmonds thought. 

From there, Edmonds’ non-profit organization Hemp4Water was born. 

At that time, Edmonds struggled to realize his mission. Hemp was not yet legal on a federal level, and the water conservation organization he had been involved with at the time wasn’t interested in pursuing an illegal crop. 

Edmonds found a friend in Bill Wohlsifer, who ran for Florida Attorney General in 2014. Wohlsifer told Edmonds he’d help give a voice to Hemp4Water on the condition that Edmonds ran his campaign. (Wohlsifer ran as a libertarian.) While Wohlsifer lost, Edmonds says Hemp4Water started to gain traction. 

Edmonds became involved with trying to pass hemp legislation through the state, working with lawmakers through various pieces of legislation that were sidelined and tabled.

Then, the Agriculture Improvement Act of 2018 (the 2018 Farm Bill) federally legalized hemp.

Getting Started

After that, Edmonds’ mission took off. Through his hemp advocacy, he connected with Kendall Carson, an agricultural program coordinator at South Florida State College, to partner with and carry out the experiment. They received a license in February to cultivate hemp under Florida’s pilot program (before the U.S. Department of Agriculture approved a new state plan for Florida) and have been setting up their grow operations ever since.

They selected several different industrial hemp strains to start off with, some of which are “legacy strains” that have been grown in the U.S. for centuries, and others that come from from similar latitudes in China. He adds that he plans to explore at least a dozen other strains over the next couple months to see which one absorbs the most nutrients from the water.

Photo courtesy of Steve Edmonds.
Hemp seeds are placed in holes drilled into the mat.

Edmonds and Carson currently have two grow operations set up on a lake at South Florida State College. 

The hemp grows on porous mats that can hold up to 36 hemp plants each and allow water to move throughout them freely. Edmonds drilled holes in the mats to drop in clay balls that hold the hemp seeds. Once the seeds mature, their roots will begin growing into the water. “By reaching into the water, the plants uptake nutrients, using it to grow themselves,” Edmonds says.

While Edmonds has a history of hemp advocacy, he also chose the crop because it has a wide variety of end uses. “We’ll be removing nutrients from the water cycle, and we’re using a plant that’s going to have a use afterward,” Edmonds says.

Edmonds and Carson are building off of a Canadian study by Manitoba Agriculture, Food and Rural Initiatives (MAFRI), which shows that hemp removes a total of 200 kilograms per hectare (about 180 pounds per acre) of nitrogen and about 45 kilograms per hectare (about 40 pounds per acre) of phosphorus from the soil during its growth cycle.

“If we determine a hemp plant can take up those numbers, that’s a home run, and we can do some really amazing things really quickly,” Edmonds says. “If the numbers come in at half, that’s still really good. If they’re at a quarter, it’s worth continuing research to see if we can do it better. Any less than that, and it wouldn’t work out.”

Looking Ahead

The researchers will know by October what their next steps will be.

Edmonds is currently working on setting up a few other locations to grow hemp on waterways, including a private research location and Lake Okeechobee itself. He and Carson will also conduct a terrain study with a quarter-acre for each strain to have land-based numbers for comparison.

Ultimately, Edmonds envisions farmers across Florida—and across the country—using this method to not only provide for themselves, but also restore waterways to their natural conditions.

“The ultimate goal is to clean Lake Okeechobee. If we clean that lake, we will take care of the rest of the hydrology of Florida,” Edmonds says. “Ultimately, I would love to see these floating mats in tens of thousands of acres out in the dead zones of Lake Okeechobee."