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Harmful blue-green algae toxins found in part of St. Johns River, Department of Health warns

FILE --- Blue-green algae blooms across Central Florida

DUVAL COUNTY, Fla. – The Florida Department of Health in Duval County issued a health alert after finding harmful blue-green algae toxins in part of the St. Johns River.

The public should be cautious in and around the St. Johns River near Mandarin Point, health officials said. This health alert came after health officials received the results of a water sample taken on July 8.

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According to the DOH-Duval, blue-green algae are a type of bacteria that can be found in Florida’s freshwater environments. When they bloom, algae can discolor water and produce floating mats that emit unpleasant odors. In addition, blooms can also appear as scum, foam, or paint on the surface of the water in various colors.

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Health officials said blue-green algae blooms occur more frequently during summer and fall, and some contributing factors to blooms are sunny days, warm water temperatures, still water conditions, and excess nutrients.

According to DOH-Duval, blue-green algae can produce toxins that can be harmful to humans and pets as well as ecosystems, including fish and other aquatic animals.

In addition to the alert, the DOH-Duval also provided a list of precautions that residents and visitors can take while around the area:

  • Do not drink, swim, wade, use personal watercrafts, or come into contact with waters where there is a visible bloom.
  • Wash skin and clothing with soap and water if there’s any contact with algae, or discolored or water that smells unpleasant.
  • Keep pets and livestock away from the area to avoid any contact with water. Health officials said waters where algae blooms are present are not safe for animals. For that reason, pets and livestock should use an alternative source of water when algae blooms are present.
  • Do not cook or clean dishes with water contaminated by algae blooms. Boiling the water will not eliminate toxins.
  • Eating fillets from healthy fish caught in freshwater lakes experiencing blooms is safe. Rinse fish fillets with tap or bottled water, throw out the guts, and cook fish thoroughly.
  • Do not eat shellfish in waters with algae blooms.

Sensitive individuals such as children, the elderly, and those who are immunocompromised may still be at risk even at low concentrations of blue-green algae and should avoid any exposure, health officials said.

Current information about Florida’s water quality status and public health notifications for harmful algae blooms and beach conditions is available at Protecting Florida Together.

For more information on the potential health effects of algae blooms visit this website.


About the Author
Marcela Camargo headshot

Marcela joined News4JAX in 2023. She grew up in Mexico and eventually moved to California to pursue her dream of becoming a journalist. Now, she is a proud San Diego State University alumna who has many years of experience in TV and digital journalism.

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