The proliferation of algae in the Saint John River triggers a new alert from the Ministry of Health

JACKSONVILLE, Florida – The Florida Department of Health in Duval County issued another warning Thursday regarding the presence of harmful blue-green algae blooms in the St. Johns River.

According to a press release, the alert was triggered on the basis of water samples taken from September 23 to 27. The Department of Health said the public should exercise caution around the Saint John River, but highlighted the following locations:

  • Rivière Saint-Jean – Lions Club boat launch

  • Saint-Jean River – Saint-Jean Marina

  • Saint-Jean River – Canal to Marco Lake

  • Saint-Jean River – mouth of Craig Creek

  • St. Johns River – mouth of Goodbys Creek

  • St. Johns River – Yacht Basin, near Ortega

  • Saint-Jean River – south end of Hart Bridge

  • St. Johns River – in Worth Dr. S

  • St. Johns River – Christopher Creek – below San Jose Boulevard.

  • Saint-Jean River – Pointe Mandarin

Health officials say the public should exercise caution in and around the Saint John River and at these places.

  • Do not drink, swim, wade, use a personal watercraft, water ski or boat in waters where there is a visible bloom.

  • Wash your skin and clothes with soap and water if you come in contact with algae or discolored or smelly water.

  • Keep pets away from the area. Waters where algae blooms are present are not safe for animals. Pets and livestock should have a different water source if there is an algae bloom.

  • Do not cook or clean dishes with water contaminated with algae blooms. Boiling the water will not flush out toxins.

  • Eating healthy fish fillets from freshwater lakes plagued with flowers is safe. Rinse the fish fillets in tap or bottled water, discard the innards and cook the fish well.

  • Do not eat shellfish in waters with algae blooms.

Less than two months ago, the Department of Health issued an alert for potentially toxic algae at locations along the St. Johns River and Julington Creek in Mandarin.

What are blue-green algae?

Blue-green algae are a type of bacteria common in Florida freshwater environments. Abloom occurs when the rapid growth of algae leads to a build-up of individual cells that discolor water and often produce floating mats that emit unpleasant odors.

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Some environmental factors that contribute to blue-green algae blooms are sunny days, warm water temperatures, calm water conditions, and excess nutrients. Flowers can appear year round but are more common in summer and fall.

Are blue-green algae harmful?

Blooms of blue-green algae can impact human health and ecosystems, including fish and other aquatic animals. For more information on the potential health effects of algal blooms, visit

Find up-to-date information on the state of Florida’s water quality and public health notifications regarding harmful algal blooms and beach conditions by visiting To report blooming to DEP, call the toll-free helpline at 855-305-3903 or report it online. To report fish deaths, contact the Florida Fish and Wildlife Research Institute at 1-800-636-0511.

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Report symptoms of exposure to a harmful algal bloom or any aquatic toxin to the Florida Poison Information Center, call 1-800-222-1222 to speak to a poison specialist immediately. Contact your veterinarian if you think your pet has become ill after consuming or coming into contact with water contaminated with blue-green algae.

If you have any other health questions or concerns about blue-green algae blooms, please call the Duval County Florida Department of Health at 904-253-1280.

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