Green Waters are a Red Flag: Water Quality and Algal Blooms

Next week marks the beginning of Water Quality Month, which is particularly timely this year as we enter August surrounded by news of harmful algal blooms damaging water quality in Utah Lake, Hell’s Canyon Dam, and in the waters off the coast of south Florida. While you’re probably able to identify a harmful algal bloom when it’s turned your local water body an unnatural color (which can sometimes be visible from space) and emitting an odor likened to “rotting meat,” it’s also important to know how these public health threats are generated, and what you can do to help avoid having these blooms crop up in your community, where they can be a danger to plants, animals, and people.

“Algae” is a broad term used by scientists and health experts to describe a variety of photosynthetic organisms that use sunlight, water, and carbon dioxide to produce oxygen and energy. Though some species of algae resemble plants, they lack traditional roots, stems, and leaves, putting them in a separate category of their own. Even within this special grouping, there are many different types of algae—some can be smaller than 1/10th of the width of a human hair, while others will grow to be over 100 feet long!

Algae All Around Us

Though we often cannot see them, algae are all around us – found on land, in the sea, and in fresh and brackish water. They’re a natural part of the environment, serving as the base of many food chains—a role that they‘ve had for quite some time. One type of algae, cyanobacteria, or blue-green algae, are the oldest known fossils on Earth, dating back 3.5 billion years! Cyanobacteria are still around today, forming one of the largest groups of bacteria on the planet. If cyanobacteria sound familiar, it might be because you’ve heard that they can be responsible for these harmful algal blooms.

While these algal populations are a natural and integral part of the ecosystem, their numbers can spiral out of control in the right conditions—warm water, lots of sunlight, and with plenty of nutrients available in the water. When these factors come together, sometimes with the help of stormwater runoff, nutrient pollution, and overuse of fertilizer, algae populations can spike, creating what is referred to as an algal bloom.

Adverse Effects of Algae

Algal blooms come in many colors and can have serious negative health impacts on humans and animals by contaminating waterways and drinking supplies. Cyanobacteria is the predominant culprit behind toxic algal blooms in freshwater systems. These bacteria produce cyanotoxins that can impact the liver, the nervous system, respiratory system, and the skin of those who are unfortunate enough to come into contact with them. Drinking, bathing, or swimming in contaminated waters can lead to an array of negative health impacts including blisters, fever, muscle and joint pain, paralysis, asthma, and allergic reactions such as rashes. In extreme cases, the deaths of wildlife and domestic animals have been reported in association with toxic algal blooms, such as was the case with eight manatee deaths in the midst of Florida’s algal bloom in June.

Exercise Caution

If you see a body of water with surface discoloration such as a red, green or brown tint, especially if the water has a thick, mat-like accumulation of scum on the shoreline and surface coupled with an unpleasant smell, remember these tips:

  • Stay away from it. Do not use the water for swimming, boating or fishing. Keep children and pets away as well.
  • If you accidentally come into contact with water you suspect is contaminated, immediately rinse off with clean, fresh water.
  • Do not attempt to kill the algae with algaecides yourself—by killing the algae, the cells are burst, which can release the toxins into the water. Allow professionals to determine if a chemical treatment is necessary.
  • If you think someone has been poisoned by a toxic algal bloom, seek medical attention immediately.
  • Report algal blooms to your state’s department of health or environment, which can then feed your report into CDC’s new national reporting system, One Health Harmful Algal Bloom System. Find your state’s contact information.

To learn more about the ways in which harmful algal blooms can be inadvertently created and sustained, check out our new online course, the Watershed Sleuth Badge Program. Simple, everyday actions you take at home and in your community can have a big impact on water quality—for better or for worse! Learn more about how you can help improve water quality in your community.