Protecting Our Water

An algae bloom is considered generally safe up to a point. That point, or threshold, is referred to as the Recreational Water Quality Criteria, which is from criteria recommended by the EPA.

The Recreational Water Quality Criteria reflects the latest scientific knowledge, public comments and external peer review. The criteria are designed to protect the public from exposure to harmful levels of pathogens while participating in water-contact activities such as swimming, wading and surfing in all waters designated for such recreational uses. In the last few years the acceptable levels have been lowered in an effort to protect citizens. In 2012 the acceptable level was 110 cfu/100mL, it was then lowered to 104 cfu/100mL, and in 2019 the Recreational Water Quality Criteria was reduced to 71 cfu/100mL.

Through the Healthy Beaches Monitoring program, the Martin County Health Department, Division of Environmental Health, conducts beach and river water sampling in eight locations throughout the county every other week.

In addition, the Martin County Health Department conducts weekly St. Lucie River sampling at four sites. These sites are sampled as a special monitoring project and the reports may be found here.

Call Poison Control at (800) 222-1222 for advice if you are having health problems you think are related to an algae bloom.

Blooms can last days, weeks or months, depending on conditions. Scientists cannot predict when or where blooms will occur or how long they will last; the blooms run their course and dissipate naturally.

Beaches are guarded, however, conditions may change on a daily basis. Residents and visitors are encouraged to seek the assistance of EMT/Lifeguards with any questions or concerns while at guarded beaches.

Important Resources

• For the latest information on Martin County beaches updated daily, call the beach hotline anytime at: (772) 320-3112
• All beaches are tested weekly and results are posted on the Florida Healthy Beaches Program website.
• To find out about Red Tide conditions throughout the state of Florida, please call: (866) 300-9399
• FWC reports on the current status of Red Tide using tables, static maps, and interactive Google Earth maps. For more information, visit Florida Fish and Wildlife Conservation Commission
• Check out our beach cams to get a first hand view of current conditions.

Important Resources

• Please report algae blooms or sightings to the Florida Department of Environmental Protection (DEP) at: (855) 305-3903 or online here

Call Poison Control at (800) 222-1222 for advice if you are having health problems you think are related to an algae bloom.

Both are algae and both are in bloom in the summer, but a different microorganism is to blame for each.

The Difference

Blue-Green Algae is caused by different types of cyanobacteria, namely Microcystis aeruginosa. It has some species that can be found in the ocean, but the Blue-Green Algae blooms Floridians are familiar with occur in fresh and brackish water habitats, meaning lakes, rivers and estuaries. These blooms are unpredictable, but researchers believe they tend to happen after heavy rainfall causes pollution from the land to run off into the water. While Red Tide tends to occur cyclically, Blue-Green Algae blooms are more weather-dependent, so it’s harder to know when they will begin and end.

Red Tide is caused by the algae Dinoflagellate Karenia brevis, or K. brevis for short. It is exclusively found in the Gulf of Mexico, meaning you’ll only see it on beaches along the west coast. Red Tide occurs almost every year in the Gulf of Mexico during late summer to early fall.

Health Effects

Blue-Green Algae blooms can cause humans to experience nausea, vomiting and even acute liver failure in severe cases if the affected water is ingested. Skin irritation, swollen lips, eye irritation, earaches and sore throats are other symptoms people can experience if they swim in water during a Blue-Green Algae bloom, although swimming or any other contact with the water is not recommended.

Red Tide is the one killing countless fish and other marine life — birds, manatees, sea turtles and more. That’s because when K. brevis dies, it releases a toxin that affects the central nervous system of any creature that consumes it, particularly fish, eventually causing death. The toxin can become airborne when water breaks, causing sneezing, coughing, throat irritation and other respiratory issues for anyone who breathes it in, including humans.

Learn more about Red Tide vs. Blue-Green Algae here.

Blue-Green Algae, or “cyanobacteria,” are natural to the environment’s food chain and are found all over the world. They are actually a type of bacteria but, like plants, they can use sunlight to grow.

Blue-Green Algae are a group of organisms that are among the oldest on the planet. They can be found in marine waters as well as freshwater and brackish habitats.

Some – not all – Blue-Green Algae can produce toxins that can contribute to environmental problems and affect public health. Those Blue-Green Algae that are known to produce toxins do not always do so. Little is known about exactly what environmental conditions trigger toxin production.

Blooms can float on the surface and be several inches thick or they can lie below the surface of the water. Blooms can disappear from view or move to different parts of a waterbody.

Blue-Green Algae multiply quickly in water bodies with high nutrient levels such as phosphorus or nitrogen, and particularly when the water is warm and the weather is calm. That’s why Blue-Green Algae are most common in Florida in the summer and early fall, with its high temperatures and abundant sunlight, although they can occur at any time.

Waters that flow slowly with low turbulence – such as impounded rivers, dams, or water storages – are at particularly high risk of algal blooms.

Blue-Green Algae growth can become seemingly explosive when lots of nutrients are present, providing a rich feast that can then cause “blooms” that may look like floating carpets of Blue-Green Algae turning the water green.

Increased nutrient loading in our waterways has likely contributed to increased frequencies of blooms in our freshwater systems.

Microcystis toxin, a class of toxins produced Blue-Green Algae, is measured in micrograms/liter. Currently any measurement over 10 micrograms/liter triggers posting of “no human contact” signs. Florida Department of Environmental Protection has a sampling schedule and posts results from samples tested here.

In Florida, Red Tide is a naturally occurring microscopic algae called Karenia brevis or K. brevis that is present in background conditions throughout the year in the Gulf of Mexico. It occurs in salt water and when natural conditions are right, the organism can form blooms off the coast producing a toxin that can affect the central nervous systems of fish and wildlife. At high concentrations, the blooms may discolor the water – sometimes red, light or dark green, brown or clear.

Most people can swim in Red Tide, but it can cause skin irritation and burning eyes. If you experience irritation, get out and thoroughly wash off with fresh water.

For most people, symptoms are temporary. Some people may experience eye, nose, and throat irritation, as well as coughing, wheezing, and shortness of breath when on the beach or in an area near a Red Tide bloom, particularly when winds are blowing onshore. According to the Florida Department of Health, people with severe or chronic respiratory conditions should avoid Red Tide areas.

Call Poison Control at (800) 222-1222 for advice if you are having health problems you think are related to an algae bloom.

Can people swim in Red Tide?

Florida Fish and Wildlife Conservation Commission states that most people can swim in Red Tide, but it can cause skin irritation and burning eyes. If you experience irritation, get out and thoroughly wash off with fresh water.

Can pets swim in Red Tide?

If your pet swims in a Red Tide bloom at the beach, rinse thoroughly with fresh water as soon as possible. Don’t let your pet play in sea foam near a Red Tide bloom.