What’s an Algae Bloom?

You may be hearing news reports about algae blooms in area lakes or other bodies of water. That sounds ominous, but is it? Can an algae bloom make water unsafe to drink or swim in? Is this something normal? 

An algae bloom is an overgrowth or speedy accumulation of algae in a freshwater or marine (saltwater) environment. Algae bloom concentrations can reach as high as millions of cells per millimeter. There are literally thousands of species of algae, AKA phytoplankton, living happily in marine and fresh waters around the globe. 

They’re a crucial component of life as we know it – they form the basis of the food web, which is the entirety of interrelated food chains in an ecological community. Most species are harmless to people and animals. Some are toxic, though, and when toxic algae multiplies it can cause harmful algal blooms (HABs) which can cause havoc. Human, and animal health is affected including wildlife and pets, seafood becomes contaminated and local economies reliant on tourism or fishing can be devastated.

Usually an algae bloom is made up of only one or a few phytoplankton species. Specific blooms can be spotted easily because the water becomes discolored. The color of the algae-bloom water depends on the species of algae or bacteria involved in the bloom. Most often algae blooms appear yellowish-brown, red or green. Depending on the type of bloom, bodies of water can develop a paint-like slick appearance, look foamy or frothy, or develop a foul-smelling scum. 

Algae blooms are triggered by a variety of factors, sometimes occurring in combination. They most often form in bodies of water where there is run-off from other lakes, farms or other nutrient sources. Higher temperatures in the summer and early fall cause water temperatures to rise, which can cause the bacteria in the water to grow rapidly. Over the past 40 years, freshwater algae blooms have become an environmental problem in all 50 states. 

Three common types of algae blooms are red, brown and green/blue-green. Most blooms are just a normal part of marine or freshwater ecosystems and most are nontoxic. They can last anywhere from a few days to a few months, and while some blooms are visible, many others offer no visual indication that they are present. Algae blooms that you can see are not always toxic; invisible algae blooms can be toxic or not.

A report by the Congressional Research Service indicates that in recent years, the frequency of harmful algal blooms (HABs) has been increasing, and they are happening in more and more areas nationally and globally. The impacts of HABs can be severe and widespread—often with interstate implications: in 2014, a massive HAB in Lake Erie affected the drinking water for more than 500,000 people in Toledo, Ohio; two years later a giant HAB in Florida’s Lake Okeechobee impacted tourism and aquatic life.  

Many types of algae can cause HABs in freshwater systems. The most frequent and severe blooms involve the growth of cyanobacteria. Some cyanobacteria species can produce toxins (cyanotoxins) that can cause mild to severe health problems in humans and can kill aquatic life and other animals.  

Blue-green algae (BGA)  blooms, another name for cyanobacteria, can show up in freshwater lakes, rivers and streams during the summer and warmer months. The blooms are usually caused by high temperatures, especially after rain. The blooms occur due to changes in the nutrient levels in the water, that when heated, can cause the bacteria to grow at a rapid rate. Blooms mostly occur along shorelines and where water is shallow or stagnant. The blooms can move, grow or shrink depending on conditions, so recreational water users should be on the lookout for them.

Blue green algae can produce toxins that may contaminate drinking or recreational water and can produce toxins that can cause illness or worse in humans and animals. The Oklahoma State Department of Health tells us that possible health effects can vary and are dependent upon the type of toxin present and the route of exposure. Contact with high concentrations of cyanobacteria, independent of the level of toxins, may also cause adverse health effects.

Types of exposure to BGA and correlating symptoms include:

• Skin Exposure: rash, hives, or skin blisters.
• Inhalation: runny eyes, runny nose, sore throat, asthma like symptoms, or allergic reactions
• Ingestion: Acute, severe gastroenteritis (stomach cramps, nausea, diarrhea or vomiting)

How long it takes to develop symptoms after coming into contact with BGA is unknown. Serious health effects like liver toxicity may take hours or days to become evident in humans or animals; neurotoxicity symptoms may appear within 15 to 20 minutes after exposure. There are currently no tests to detect cyanobacteria toxins or antibodies in humans.   

The Oklahoma State Department of Health (OSDH) recommends individuals to avoid swimming or participating in water recreational activities where water is discolored or where you see foam, scum, or mats of algae on the water.  Individuals are also advised to follow any water body closures announced by the Department of Environmental Quality or Grand River Dam Authority. 

Safe drinking water and algae blooms

Drinking or accidentally ingesting water with high concentrations of BGA can make you sick. People can become sick if they swallow or have skin contact with water that is infested with the bacteria, or breathe in water droplets while swimming, boating, waterskiing or tubing in untreated water sources. Symptoms may include vomiting, diarrhea, rash, eye irritation, coughing, a sore throat and/or headache. See a doctor immediately if you know you’ve ingested or come into contact with blue-green algae.

Bloom-infested water can easily be fatal to pets.

The treatment systems used by large cities, including City of Oklahoma City use technologies that are capable of eliminating harmful bacteria from raw water sources. This includes the type of bacteria that is caused by blue-green algae.

Your tap water is safe. For more Oklahoma health information, check out the rest of our INTEGRIS Health For You blog.