Dead speckled sea trout and redfish are washing up along the Guana Preserve in Ponte Vedra Beach. A St. Johns County commissioner plans to join environmental staff for water sampling Thursday.

The fish kill is the second reported in the preserve this month, according to News4Jax, which first reported the story Tuesday. Wind has pushed floating carcasses in various stages of decay to the shoreline, and the smell of decomposition is noticeable along the water's edge.

Matt Chipperfield, a local fishing guide and environmentalist, told News4Jax one of the dead fish was a speckled sea trout roughly 27 inches long.

"Every one of those we lose, you're not just losing that fish," Chipperfield said. "You're losing the millions of eggs she might have produced during the next spawning season."

The exact number of dead fish is unknown because many carcasses sink, decompose or are eaten by wildlife, the station reported.

Stormwater runoff cited as a possible cause

Chipperfield said stormwater pollution from nearby communities may be driving the fish kills. He described runoff from the Sawgrass community flowing through storm drains, canals, ponds, golf courses and lawns into the watershed before reaching the preserve. He cited research he said found harmful stormwater pollutants and effluent entering the preserve increased 600% over the past six years, though the report did not name the study.

A separate study published in the July 2025 Marine Pollution Bulletin found the Guana Estuary watershed above Mickler's weir is 81% developed land. Of that, 55% is classified as highly developed, according to a Flagler College Gargoyle report. Only 19% of the watershed remains natural.

Low oxygen and copper add to concerns

Linda Krepp, a longtime resident and former environmental educator at the Guana Tolomato Matanzas National Estuarine Research Reserve, told the Gargoyle in a Sept. 17 article that excess nutrients from fertilizer runoff and reclaimed wastewater from communities and golf courses to the north appear to be contributing to water quality problems in Guana Lake.

A multiyear reserve study also found low dissolved oxygen levels in Guana Lake, which stresses aquatic life, the Gargoyle reported. Copper pollution from stormwater ponds is another concern. Copper-based algaecide used in retention ponds to control algal blooms can discharge into natural waterways, causing gill damage and death in fish.

The Guana River carries an Outstanding Florida Water designation from the Florida Department of Environmental Protection, a classification that requires protection of existing water quality.

Advocates urge county commission to act

Chipperfield is asking the St. Johns County Board of County Commissioners to adopt a water quality resolution or a reasonable assurance plan. He said environmental and state agencies have proposed several restoration options. Environmentalists hope to present a plan to the commission in the coming weeks, though no meeting date has been set.

A commissioner, who was not named in the News4Jax report, said the county is preparing to investigate.

"I'm actually going with the environmental team on Thursday morning to take water samples ... I think it's our responsibility to step up to the plate," the commissioner said.

No official county statement or press release on the fish kill had been published as of Wednesday.