This summer was hot and water levels in many places were low. Those are ripe conditions for harmful algal blooms. But state environmental regulators say reports of blooms are lower than previous years.
Harmful algal blooms happen under certain conditions where naturally occurring blue green algae grows rapidly. As the algae dies, it releases harmful toxins into the water that can be fatal if ingested by people, pets and livestock. Blooms are triggered by warm temperatures, nutrient runoff and sunlight.
Tiffany Lyden does education and outreach for the Montana Department of Environmental Quality.
“This year, we've had about 35 reports of harmful algal blooms. Typically in a full year, we have anywhere between 45 and 65,” Lyden said.
Lyden says water with patches of unnaturally bright colors, or the appearance of spilled paint, can indicate signs of a harmful algal bloom.
“One thing I tell people to look at, is if they can kind of poke the water with a stick or something. And if the algae doesn't cling to it, it doesn't hold its shape. Then it's probably a blue green algae,” Lyden said.
DEQ relies on public reports to detect the presence of harmful algal blooms. Once the agency receives a report, it investigates and posts advisories as needed. Lyden says limiting fertilizer and stormwater runoff can help prevent harmful blooms. Native vegetation along rivers and lakes also helps filter out nutrients that feed that algae.
Although fall is approaching, Lyden warns warmer weather expected this fall means blooms are possible. Most reports come from larger water bodies where nutrients can accumulate, like Canyon Ferry Reservoir, Clark Canyon Reservoir and Holter and Hauser Lakes.
