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Another Biscayne Bay Fish Kill Signals Ongoing Problems

Sunrise showing a fish kill in Biscayne Bay
Courtesy of Kathryn Mikesell
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In August, dead fish pictured here were found along the western shores of northern Biscayne Bay.

Dead fish spotted in Biscayne Bay’s busy urban north end over the weekend again signaled ongoing problems with pollution possibly worsened by heavy flushing from the Little River.

Miami Waterkeeper began receiving reports of dead fish from Haulover Inlet to Albert Pallot Park near the Julia Tuttle Causeway Saturday morning, said executive director Rachel Silverstein. County environmental regulators also received calls Saturday, but were only able to confirm a few fish in canals in North Miami, a spokeswoman said.

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While far less widespread than dead fish found in August, Silverstein said any kill is concerning.

“We're still having bad water quality conditions that are causing our wildlife to die and to suffocate essentially in place and basically turn the bay into a dead zone in these parts of northern Biscayne Bay,” she said.

Following a spike in chlorophyll late Friday night, oxygen levels plummeted early Saturday, according to monitoring by Florida International University in the Tuttle Basin started after the August fish kill. Chlorophyll is used to predict algae in water.

The conditions also coincided with ongoing elevated water flow from the Little River.

Scientists suspect freshwater flushing from the river may be driving down oxygen in the bay, where heavy pollution has killed off much of the seagrass that might make the bay more resilient to low oxygen.

University of Miami ocean chemist Chris Langdon found flows dropped in August, but climbed again in September and October to nearly four times historic averages. High temperatures and low winds that likely contributed to poor conditions in August were not present over the weekend, suggesting the high flows may be a culprit.

october 2020 Little River flows
Chris Langdon
Flows out of the Little River, shown in blue, were again elevated in September and October. Flows from the Biscayne Canal, in red, also increased.

“We’re being able to narrow down here what are the inputs,” Silverstein said. “And it's looking more and more like it might be related to what's coming out of the Little River and the flow, although more research is needed to confirm that.

County sampling done Saturday, as part of a monthly monitoring program, also found low oxygen levels at the mouth of the Biscayne Canal and Little River, where the August fish kills were spotted.

The increased flows from the Little River were likely due to heavy rain, said South Florida Water Management District spokesman Sean Cooley. District officials suspect a combination of increased development, paving over surfaces, sea rise and higher groundwater elevated by rising seas are putting more water into the river, he said.

The river drains dense neighborhoods around Little Haiti and El Portal and ultimately connects to the Miami Canal.

Problems at the bay’s north end have increasingly drawn attention to worsening conditions across the bay. Last year, the National Oceanic and Atmospheric Administration warned the bay was gradually losing its clear waters and undergoing a shift to murkier water filled with macro algae.

In August, following more than a yearlong review, the county’s Biscayne Bay Task Force issued a report calling for a new chief bay officer and board to oversee efforts to clean water and restore wilted seagrass.

On Tuesday, county staff was scheduled to provide details on how plans would be implemented during a county commission meeting. But Commissioner Rebeca Sosa, who created the task force, asked to delay the presentation until a written report could be made.

Miami-Dade Mayor Carlos Gimenez’s administration is already behind on two other reports: a Biscayne Bay report card, that is two years overdue, and a plan to deal with aging septic tanks across the county.

Commissioner Danielle Levine Cava, who asked for the reports, opposed the delay and said the information could shed light on ongoing problems.

“I'm asking for other reports that have been requested and are overdue and provide a lot of detail,” she said.

WLRN also submitted a request under Florida’s Sunshine Law in mid-August asking for drafts of the reports. Despite repeated requests, the reports have not been provided nor has there been an estimate for when they will be produced.