Blue-Green algal bloom observed by St. Johns River Water Management District

Algae are plant-like organisms that help sustain aquatic life by contributing to the food chain and providing oxygen to keep Florida’s waterbodies healthy. Certain conditions, such as warm weather and increased nutrients, may cause the rapid growth of algae. This rapid growth can cause an algal bloom (or algae bloom). 

An algal bloom may look like foamy mat or a scum layer on the surface of the water. Some blooms release toxins that are harmful to people and the environment. A harmful algal bloom (HAB) may occur in a saltwater, freshwater or brackish waterbody.

The most common HABs in Florida are due to blue-green algae (cyanobacteria) in fresh waters and Red Tide (Karenia brevis) in coastal waters.

On Jan. 10, 2019, Governor DeSantis issued an executive order (EO), addressing HABs. The EO included multiple directives to improve water quality throughout Florida.

Governor DeSantis signs SB712





Another historic step was taken on June 30, 2020, with the governor's signing of Senate Bill 712. This bill carries a wide range of water quality protection provisions aimed at minimizing the impact of known sources of nutrient pollution, realigning the state’s resources to enhance the protection of Florida’s environment and strengthening regulatory requirements.

Learn More about State Action

State Action Timeline  Grants Information  Restoration Initiatives 



What Does an Algal Bloom Look Like?

Blue-Green algae written over algal bloom.
Don’t wade, swim or swallow water where there are algae blooms. With so many places in Florida to explore, we sometimes forget our beaches, lakes and rivers are natural places that change with the seasons.
Blue-green Algal bloom observed in marina in Indian River Lagoon
Blue-green algal bloom observed in the Indian River Lagoon by St. Johns River Water Management District
Blue-green Algal bloom observed in Bull Creek upstream of Bull Lake
Blue-green algal bloom was observed by DEP in Bull Creek, upstream of Dead Lake.
Green scum layer on water near control gates.
Blue-green algal bloom observed by the South Florida Water Management District in Lake Okeechobee. The bloom was present on the water surface and suspended in water column. The bloom was impounded against control gates on the upstream side of structure. The bloom was about 12 meters wide and 15 meters long.
Aphanizomenon Flos-aquae. Marbled green discoloration is observed.
Aphanizomenon flos-aquae is a brackish and freshwater species of cyanobacteria. This bloom was observed in the St. Johns River in 2010.
Patch algal bloom observed. Bloom appears as patchy green algal mat on the surface.
Microcystin aeruginosa is a species of freshwater cyanobacteria which can form harmful algal blooms. This bloom was observed by the St. Johns River Water Management District.
Green discolored water.
Aphanizomenon flos-aquae, a brackish and freshwater species of cyanobacteria, was observed throughout the water column. The bloom was observed in the Manatee River at Poinsettia Ave.
Red Tide written over photo of a beach with discolored water and a scummy layer visible in the surf.
Don’t wade, swim or swallow water where there is red tide. With so many places in Florida to explore, we sometimes forget our beaches, lakes and rivers are natural places that change with the seasons.
aerial view of Red Tide Bloom.A brownish water discoloration is observed.
FWC conducted an aerial survey for red tide in 2018. A patchy bloom was observed along the 1-mile survey line. Water discoloration was visible from Pinellas County to Sarasota County, within 3 miles from the coast.
FWC Aerial survey for red tide shows streaks of discoloration.
FWC conducted and aerial survey for red tide in 2018. This photo was taken between the 5 and 10-mile survey lines. Although the bloom was patchy, defined golden-green streaks indicative of red tide were observed. Observations from the 10- mile survey estimated that the bloom extended at least 15 miles offshore in some areas. In particular, this was noted off of Manatee and Sarasota counties.
Image of red tide bloom taken from the shore, showing brownish discoloration
Image of red tide bloom taken from the shoreline. Photo courtesy of Florida Department of Health.
Image of Protecting Florida Together water quality dashboard

Water Quality Status Dashboard

The Protecting Florida Together Water Quality Dashboard delivers relevant water quality information statewide including blue-green algae, red tide and nutrient monitoring data. This map helps to ensure transparency and accountability with respect to our water quality data and its exchange with the public. Information for this map provided by DEP and FWC.

Water Quality Dashboard  Dashboard Overview

Collage of DOH Logo, aquatic toxins contact info, photo of red tide and DOH infographic


Staff at the Florida Department of Health’s Aquatic Toxins Program work every day to keep Floridians and visitors to our state safe. DOH works in coordination with many partners, including DEP and FWC, to ensure public health is protected.

Florida Department of Health

Screen grab from Center of Disease Control page. Page includes general information, illness and symptoms, sources of exposure and risk factors, HABs and the Environment, Prevention and Control, Publications, Data and Statistics.

Center for Disease Control

The Centers for Disease Control and Prevention (CDC) serves as the national focus for developing and applying disease prevention and control, environmental health, and health promotion and health education activities designed to improve the health of the people of the United States. The CDC provides additional information on harmful algal bloom related illness, including sources of exposure, risk factors, illness and symptoms.

Centers for Disease Control and Prevention

Collage of What is Eutrophication Video from NOAA. Image of US, Image of bacteria discharging carbon dioxide, NOAA logo, Image of fish breathing oxygen

What is Eutrophication?

Learn about eutrophication from the National Oceanic and Atmospheric Administration. Eutrophication is a big word that describes a big problem in the nation's estuaries. Eutrophication occurs when the environment becomes enriched with nutrients, increasing the amount of plant and algae growth to estuaries and coastal waters.

Learn about Eutrophication

Learn More About Blue-Green Algae

Learn More About Red Tide