You’ve probably heard about the algal blooms that are affecting Lake Okeechobee, as well as some canals and shorelines in Martin, St. Lucie, Palm Beach, and Lee Counties.  Officials are closing beaches and instructing the public to stay out of the water altogether hurting water oriented businesses and tourism along the Treasure Coast and the Southwest Coast of Florida.  Governor Rick Scott has declared a state of emergency for the four counties because of the algae. Many questions have been raised by the public, so below we’re going to answer some of the questions that we’ve heard brought up often over the past few weeks.


Why is the water green?

Cyanobacteria, also called blue-green algae, are a group of bacteria that are commonly found in nearly all bodies of water in the world. They typically are found at relatively low levels, including multiple different species. When conditions are right, the population of one or more species of cyanobacteria may rapidly increase, causing a visible “bloom” of green or blue-green in the water.


Why does the water smell?

When the blooms of cyanobacteria die off, they decompose releasing gases into the air. These gases sometimes include hydrogen sulfide, or other gases which have odors we associate with decomposing plants or fish.

Is the water toxic?

Certain species of cyanobacteria produce toxins, which may be present in either the algae or the surrounding water. The Florida Department of Environmental Protection (FDEP) has collected samples of water and algae from various locations to assess toxicity. Two samples collected in the St. Lucie River contained toxins above the hazardous levels. Other samples are still awaiting results. The CDC states that “swallowing water that has algae or algal toxins in it can cause serious illness.”

Is this algae bloom related to discharges from Lake Okeechobee?

It is likely that the bloom is caused by excess nutrients (phosphorous and nitrogen), some of which may have originated in and around Lake Okeechobee and been released during some of the controlled discharges by the Army Corp of Engineers lowering the lake to protect the aging dike system. Excess nutrients are also commonly released through stormwater runoff and septic tank discharge within the watershed. A single source has not been identified for the current bloom. Water managers and scientists believe the excess nutrients from Lake Okeechobee combined with the high levels already present in the watershed from other sources is probably causing the water quality to reach the “tipping point” thus promoting the alae blooms.

Are fish and wildlife being harmed by the algae blooms?

Oxygen levels are significantly reduced during algae bloom crashes when the decomposing algae will use up the dissolved oxygen. This can cause fish kills to many species and will stress other forms of aquatic life making them susceptible to sickness and death.  Seagrasses will die off with the lack of sunlight reaching them due to the algae. And organisms like oysters that filter feed will die off due to the lower salinity levels from all the freshwater being introduced into the estuary. Marine mammals and birds will essentially vacate the areas because their normal food sources are no longer available.

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Photo Credit: Photo by John Moran – EPA/Environmental Protection Agency / Public Domain (CC0)