Harmful algal blooms in recreational water: When in doubt, stay out!

Most of the year, Idaho’s lakes and reservoirs are safe to enjoy. But when water temperatures increase, as they typically do in July and August, and the right type of nutrients are available, some bodies of water can produce blooms of harmful bacteria that can be dangerous for humans, pets, livestock, and wildlife. Those blooms are called cyanobacteria harmful algal blooms, or HABs for short. The Idaho Department of Environmental Quality is currently listing 12 bodies of water with health advisories in Idaho.

What causes harmful algal blooms?

The blooms are caused by bacteria that can produce toxins. The blooms are also referred to as cyanobacterial blooms. When weather conditions are calm and there is an increase in water temperature and nutrients, bacteria can rapidly increase and produce a bloom. Blooms can occur at any time, but they most often occur in late summer or early fall.

What do these blooms look like?

They can be blue, bright green, brown, or red and may look like paint or anti-freeze floating on the water. As the bloom develops, it may look like foam, scum, or mats on the surface of lakes and ponds.

What are the symptoms of an exposure to a bloom?

The most common health effects are skin and eye irritation. Other more severe effects can include:

  • Difficulty breathing
  • Stomach pain
  • Nausea
  • Vomiting
  • Diarrhea
  • Dizziness
  • Numbness and tingling in lips, fingers, and toes
Continue reading “Harmful algal blooms in recreational water: When in doubt, stay out!”