DEQ Officials warn about harmful algal blooms ahead of warm weather, holiday weekend

Blue-Green Algae
Posted at 5:37 PM, Jun 29, 2023
and last updated 2023-07-01 12:40:06-04

HELENA — As warmer weather and the Independence Day holiday approach, Montana Department of Environmental Quality officials are asking recreators in the Treasure State to be on the lookout for potentially harmful algal blooms.

Blue-green algae is a microorganism that is native to Montana waterways, but in large quantities can be dangerous to humans and animals. In order for the algae to bloom, it requires warmer water temperatures and nutrients in the water.

"It's pretty early yet in the season and it hasn't been too warm yet, so we're just starting to get a few reports that have come in on the state app that you can get to that at," said Tiffany Lyden, MT DEQ's water quality division education and outreach coordinator. "So we've had a few reports on Canyon Ferry and a couple other areas around the state, but I would imagine we'll get some more as the warmer weather starts, as things start to heat up a bit."

While still early, Lyden and officials at DEQ are asking people to be aware of the dangers associated with a potentially harmful algal bloom and if they are unsure if water is safe, to stay out of it and report it.

"When you're looking for a harmful algal bloom is what looks like kind of spilled paint or grass clippings on the surface of the water, and those are typically kind of a bluish or blue-green color, but sometimes that can be yellow or gold or red, but you'd want to really kind of look for that telltale spilled paint or splattered paint on the surface of the water," said Lyden. "It's really important before you have your kids or yourself or your dogs go into the water: is just to take a look at the water and see if you see any of those common characteristics of a harmful algal bloom and if in doubt, stay out of the water."

To report a potentially harmful algal bloom anywhere in the state, visit