Every time the weather warms up, news reports start popping up about blue-green algae outbreaks. These usually warn swimmers to stay out of certain bodies of water where the outbreak is occurring, as well as warning people not to let their pets or livestock consume the water. But what is blue-green algae and why is it dangerous? Those short news reports are often scarce on details, but understanding how and why these blooms occur and how to recognize dangerous exposure to them is an important part of staying safe during outdoor recreation.


1. What is Blue-Green Algae?

Although it only makes the news when a major outbreak occurs, blue-green algae are present in most bodies of water. The tiny cyanobacteria are microscopic organisms that usually don't collect in large enough numbers to present a health hazard. Cyanobacteria are one of the oldest life forms on the planet and can be found in soil as well.

what is blue-green algae Moniek Spaans / Getty Images


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