Harmful Algal Bloom FAQs

For the most up-to-date information regarding the lake, please subscribe to the Lake Alert service or call the Lake Alert hotline number, 407.246.2220.  

Don’t see an answer to your question? Email questions to the Public Awareness Specialist at stormwater.education@orlando.gov.


What is a harmful algal bloom?

Harmful algal blooms are the result of rapid growth of algae that can cause harm to people, animals, and/or the environment. Algae are essential and beneficial to a water ecosystem, and only a few are harmful. When algae grow too rapidly due to nutrient rich water, there becomes an algal bloom. Algal blooms themselves can be detrimental to a water ecosystem due to the rapid growth and then rapid decomposition, during which the oxygen levels are depleted and cause a loss of plants and wildlife in the surrounding area. Algal blooms can also be harmful when there are algae that produce toxins, which have harmful effects on people, fish, and other wildlife. For more information, visit the Centers for Disease Control website at cdc.gov.


What causes an algal bloom?

Algal blooms are typically a cause of warm, still water that are high in nutrients such as phosphorus or nitrogen. Runoff from fertilizers, yard waste getting into the storm drain system, pet waste, and sewage discharges will all add extra nutrients into the lakes that will contribute to algal blooms occurring. To help prevent algal blooms from occurring, here are 6 useful tips: use a 15-foot “fertilizer-free” zone around water, maintain aquatic plants along shoreline, bag your yard waste instead of blowing it into our streets, pick up pet waste, use low to zero-phosphorus fertilizer, always use GI-BMP certified landscapers.


What are the health risks associated with algal blooms?

Depending on the chemical structure of the algae, they could be neurotoxins that affect the nervous system, hepatotoxins that affect the liver, dermatoxins that affect the skin, or other toxins that affect the stomach or intestines. People and animals are exposed to these toxins through either direct skin contact or inhalation. The most common symptoms include: skin, eye, nose, or throat irritation, abdominal pain, headaches, vomiting, diarrhea, and neurological symptoms.

How long will a harmful algal bloom event last?

There are a number of factors that affect the span that a harmful algal bloom event will occur, and therefore makes it impossible to predict in advance. Blooms can last from weeks to months, but Stormwater personnel will continuously monitor an area where a Lake Alert is in effect.

Can a harmful algal bloom be stopped?

Unfortunately once an algal bloom has occurred, it needs to naturally dissipate as there are no methods to stop it. However, there are methods to prevent algal blooms from occurring, please see the “What Causes an Algal Bloom” question for more details.

How can I stay up to date on algal blooms in my area?

For the most up-to-date information regarding your lake, please subscribe to the Lake Alert service and call the Lake Alert hotline. Also, be aware of your surroundings and watch out for any warning signage that may be in your area.