Algae bloom dangers: what to know about safe swimming

Published: Jul. 4, 2023 at 5:39 PM MST
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TUCSON, Ariz. (13 News) - For many of us, Summer means relaxing by the water. It’s a great way to cool off, but can also put your family in danger, if you don’t know what to look for. Algae are in all types of water and are not always dangerous. But, when it grows out of control - blue-green algae can be poisonous to people and pets.

This particular bacteria, called cyanotoxins, can cause breathing trouble, itchy eyes, rash, headache, stomach distress, fever, and in rare cases, death. It’s particularly deadly for dogs.

“The only way to really tell if a water body is safe is being measured by water scientists,” said Lucia Ross, a water quality expert with BlueGreen Water Technologies. “But when that’s not available, just use your eyes. If you see it and it’s obvious, then you know, don’t swim in it, don’t let your pets drink the water or play in the water, don’t play in the water yourself.”

Blue-green algae can resemble pea soup or green paint, scum on the surface, or dots on or below the surface. Dry weather, like we have in Arizona, can actually make things worse because algae can be more concentrated in the heat and sun.

You’ll want to stay out of water that is discolored, slimy, smells rotten, or has foam. Do not put camping gear in it. Check for advisories and signs at lakes, creeks, and swimming holes. Boating and fishing are okay if you don’t have contact with the water. Cyanobacteria can also be on the shore.

“In a drought situation, you have a lower water table, the water is warmer, the sun’s out, photosynthesis can take place, Cyanobacteria are going to be more prevalent,” said Ross. Her motto is, ‘When in doubt, stay out.’

You can also report it when you see algae that fits this description at water bodies in Arizona. But what about your home pool? Green algae is pretty common and easy to get rid of. But what your pool cleaner might call “black algae” has the same toxins as in natural water bodies, and it can grow in pools.

You don’t want to put anything in your pool that’s come into contact with natural water sources. That includes water toys or wearing the same swimsuit.

Black algae hooks into your pool’s crevices and can look like spots or spores on the surface. Shocking will not get rid of it, so it’s best to call a specialist for help.

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