Once upon a time, water hyacinths were so thick in the Caloosahatchee a light-footed kid could stroll across them. The weed killers that knocked back their bubble-fingered invasion were hailed as miracle weapons of righteous chemical warfare.

Nowadays, though, many scientists, anglers and conservationists take a dim view of aquatic herbicides, chief among them glyphosate, the active ingredient in the controversial Roundup. The Florida Fish and Wildlife Conservation Commission seems to be taking notice.

Last week, the agency announced it would stop using them anywhere in state waters. Though other government agencies control water weeds with herbicides, the commission is the most prominent. In 2017 alone it sprayed more than 20,000 pounds on Lake Okeechobee. In Lee County, it treats the Caloosahatchee and Wild Turkey Strand and in Collier, it treats Lake Trafford and the Airport Pulling Canal in Naples.

Beyond the substances’ potential toxicity, concerns cited by opponents include the chemicals into which the products decompose and pollution caused by the accumulation of plants they kill, if those plants are not removed from the water.

"All of the nutrients that that plant ever absorbed are then released back into the water as they decay, so it's a big pulse of pollution that can cause algae blooms when that rotting plant material decays in the water," said FGCU marine and ecological science professor James Douglass. "Just spraying it and letting it lie there is a real jolt to the ecosystem."

The moratorium appears to be temporary — the agency is calling it a “pause” in order to gather public input — but it’s been warmly welcomed by environmental stakeholders.

"I think it's a very, very sensible move," said Douglass. "It'll give us a chance to observe what weed problems develop in what places ... where we really need to be spraying, and where maybe we don't."

In the meantime, the agency is hosting a series of five workshops to gather public input; the nearest to Fort Myers is in Sebring, almost 90 miles away.

Some, like North Fort Myers clinical laboratory scientist Debbie Jackow, would like it to become permanent. “All the nutrients released by spraying and putting all that weed killer in our water is killing our lakes and rivers,” she said.

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But if used properly, the herbicides are not dangerous to people, animals and wildlife, said Jason Cull, aquatic field supervisor at the Lee County Hyacinth Control District. The district uses glyphosate and other herbicides to control invasive plants in Lee and Hendry county waterways. There are 17 EPA-approved aquatic herbicides, he said.

As long as they’re applied according to the standards that the federal Environmental Protection Agency requires to be printed on the packaging, “The products are very safe,” Cull said. “The label is the law … There’s a rigorous process that each of these chemicals has to go through … they are testing this constantly.” he said. “The University of Florida, the World Health Organization – all these groups have studied, studied, studied (and) it’s not shown to have carcinogenic effects."

Far worse would be letting the weeds run wild, Cull said. “If we let it go, you wouldn’t be able to navigate the water.” If vegetation's left unchecked, many of the region’s fresh waterbodies would likely soon be clogged with weeds, leading to massive fish kills.

Audubon Florida’s Paul Gray, a longtime advocate for the lake’s ecology, said, "There needs to be some herbicide spraying in Lake Okeechobee,” Gray said. “The question is, ‘What's the right amount?’ … What we need is a vegetation management plan that describes the habitat, the goals of spraying, how to achieve those goals and how to monitor if the goals are met. Right now, they just go out and spray whenever they think it's necessary.”

And that’s way too much, said Ramon Iglesias, general manager of the Roland and Mary Ann Martin's Marina & Resort on Lake Okeechobee in Clewiston. He’d much prefer that the agency use mechanical harvesters — something like aquatic combines — to remove invasives.

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"The FWC says mechanical harvesting costs 10 times more than spraying," Iglesias said, "but it doesn't leave dead plants on the bottom of the lake to create sediment."

However, machine removal is painfully slow, said Cull.

Even so, the FWC is exploring it and other options, based on “a great deal of feedback from people concerned about our program’s use of herbicides,” said spokeswoman Carli Segelson.

One of the pause proponents is Jim Abernethy, a North Palm Beach photographer and wildlife advocate whose change.org petition, “Stop the State-Sanctioned Poisoning Of Our Lakes And Rivers!” has accumulated 173,060 signatures – and counting.

While FGCU's Douglass applauds the pause, he said it's not reasonable to expect a permanent moratorium.

"What I would really like to see would be a shift away from the spraying into mechanical removal in places where they absolutely must remove the weeds so they don't clog the drainage pipes and that sort of thing," he said. "Mechanical removal is just so much more sustainable for so many reasons"

The USA TODAY Network – Florida contributed to this report.

Connect with FWC

Information on the five workshops is at http://bit.ly/2WSsGOi

You can send comments on the FWC's herbicide spraying policies to: Invasiveplants@MyFWC.com.

Invasive aquatic plants: Southwest Florida's three worst threats

COMMON NAME: Hydrilla

SCIENTIFIC NAME: Hydrilla verticillata

DETAILS: An aquarium plant gone wild, hydrilla can grow from pieces of roots or plant fragments. Originated in China.

COMMON NAME: Water lettuce

SCIENTIFIC NAME: Pistia stratiotes

DETAILS: This Amazon basin-native forms large floating mats. It was introduced to Florida in the late 1500s when early Spanish settlers started shipping commerce between Florida and South America.

SCIENTIFIC NAME: Eichhornia crassipes

DETAILS: Not a true hyacinth, this plant does have showy purple flowers. Its wide leaves and tuberous stems help it stay afloat and form dense mats.

— The News-Press archives contributed to this report.