A dead fish floats on the surface of Biscayne Bay near downtown Miami, on Aug. 12, 2020. dvarela@miamiherald.com

Environmental groups and local governments are battling state legislators over the fate of the fertilizer in Floridians’ lawns. The outcome could sway the health of Florida’s beaches and waterways, which have been plagued by fish kills and algae blooms.

Now, it’s up to Gov. Ron DeSantis to decide the winner.

More than 100 local governments in Florida ban homeowners and businesses from fertilizing their lawns during the rainy season, when summer storms tend to wash that fertilizer into canals and out to sea. Scientists and environmental advocates say the extra nutrients in fertilizer runoff can smother sea grass, fuel algae blooms and wreak havoc on the environment.

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Miami-Dade County passed a rainy season fertilizer ban three years ago, after an August 2020 fish kill that left the corpses of more than 27,000 fish and other sea creatures bobbing in Biscayne Bay. Several South Florida city governments, including Miami Beach, Key Biscayne and Fort Lauderdale, have also imposed fertilizer bans.

But at the end of this year’s state legislative session, lawmakers slipped a provision into a budget bill that would block local governments from creating new fertilizer bans or modifying existing bans for one year, starting July 1. Existing bans would remain in place.

Local governments say fertilizer bans are one of the most cost-effective tools they have to limit nutrient runoff pollution and prevent fish kills and algae blooms, which scientists expect to become more common as climate change raises ocean temperatures and makes heavy rain storms more frequent.

“It’s a death by a thousand cuts,” said Lisa Spadafina, who heads Miami-Dade County’s Division of Environmental Resources Management. “You have runoff creating a problem. You have an increase in temperature. You have an increase in storm events. … We’re trying to address all of these things in the pieces that we can.”

A fish kill on Biscayne Bay in August 2020 helped propel new fertilizer restrictions that Miami-Dade County commissioners passed on April 20, 2021. The rules ban most applications of fertilizer during the rainy season in Miami-Dade, between mid-May and October. Farms, nurseries and golf courses are exempt from the rules. Daniel A. Varela dvarela@miamiherald.com

A coalition of 55 environmental groups, businesses and local governments wrote a letter urging DeSantis to use his veto authority to strike that provision from the budget bill, along with $250,000 in funding for a study by the University of Florida Institute of Food and Agricultural Sciences on the effectiveness of fertilizer bans.

“Governor, rainy season urban fertilizer management has been a non-partisan, common sense, science-based approach to protecting Florida’s environment and economy since 2007,” they wrote in a May 11 letter signed by the Friends of the Everglades, Sierra Club Florida and the chair of the Alachua County commission, among others.

“This was passed without public engagement at the 11th hour in a sort of sneak attack,” said Rachel Silverstein, who heads the environmental watchdog Miami Waterkeeper. “Really the only beneficiary of it is [the fertilizer] industry and not the community and not our waterways.”

DeSantis’ office did not respond to a request for comment.

The head of the Florida House Appropriations Committee, Rep. Tom Leek, R-Ormond Beach, defended the moratorium on new fertilizer bans and the funding for the IFAS study. “All that language does is give us a period of time to study it so we could make thoughtful decisions,’’ he told reporters during the legislative session.

“How water bodies die”

Nutrients like nitrogen and phosphorus can, perhaps surprisingly, cause a lot of damage in sensitive environments like Biscayne Bay and the Everglades, which naturally have very low levels of nutrients. In the bay, extra nutrients feed algae blooms which smother sea grass and leave fish without food.

“It’s a very well-known pattern of how water bodies die,” said Silverstein.

An algae bloom swirls down the Caloosahatchee River near Lake Okeechobee. Pedro Portal pportal@miamiherald.com

Fertilizer runoff is just one source of nutrient pollution in South Florida. Leaky sewage systems and septic tanks flooded by rising groundwater also dump nutrients into canals and waterways in the form of human feces.

But fixing those problems is expensive: Miami-Dade County estimates that replacing all septic tanks would cost taxpayers more than $3 billion, and each of the 120,000 homeowners with a septic tank would have to pay about $10,000 to replace their plumbing. A federally-mandated plan to plug the leaks in the sewage system will cost the county another $1.6 billion.

Banning fertilizer during the rainy season is free.

The limits of local fertilizer bans

There are limits to local fertilizer bans. Generally, they only apply to some of the ways people use fertilizer. The Miami-Dade County ordinance, for instance, makes exceptions for farms, nurseries, golf courses, athletic fields and vegetable gardens. It mainly applies to homes and businesses that fertilize their lawns.

Plus, the bans are hard to enforce. Anyone caught violating the rainy season fertilizer ban in Miami-Dade County faces a $500 fine — in theory. “Anecdotally, I don’t think we’ve given out any of these fines,” Spadafina said.

“We’re not trying to fine people,” she said. “We’re trying to get the word out to the public and to have them understand that they do play a part in the health of our community.”

Environmentalists like Silverstein say local fertilizer bans don’t go far enough. “But it is a really great first step in trying to control fertilizer-based nutrient pollution in residential settings,” she said.

This climate report is funded by Florida International University, the Knight Foundation and the David and Christina Martin Family Foundation in partnership with Journalism Funding Partners. The Miami Herald retains editorial control of all content.

This story was originally published May 14, 2023 5:30 AM.

Nicolás Rivero is a climate change reporter for the Miami Herald and the Knight Innovator-In-Residence for the FIU Lee Caplin School of Journalism & Media.