Blooms of toxin-producing algae exist in some pristine river systems, it’s a discovery from the Flathead Lake Biological Station that could have implications for Montana rivers and streams. 

In a recent study, the Biological Station uncovered some surprising results when scientists found the algae in northern California waterways. It's a finding that could have public health impacts for the entire region. 

“Algae is not bad just for being algae, its essential to rivers and lakes. If you didn’t have algae, you wouldn't have bugs... and if you didn’t have bugs, you wouldn’t have fish,” said Laurel Genzoli, a doctoral graduate at the University of Montana who led the study.  “But when there is too much, or high amounts of certain types are produced, then it begins to create an issue.”  

If consumed in large amounts, the toxic algae can prove fatal to animals and people.  

The toxin-producing algae is called cyanobacteria but is more colloquially known as blue-green algae. While technically a bacterium, it acts like algae on a basic level and looks like algae, while also creating mats like algae and photosynthesizing like algae. 

The study focused on northern California’s Klamath River watershed, which Genzoli has studied before throughout her research.  

Most algae don’t produce toxins, Genzoli said, but this blue-green algae is a group known to produce toxins in freshwater systems. While the algae hasn’t been studied in Montana nor has blooms in rivers been tested, Genzoli has observed blooms in Montana rivers.  

Cyanobacteria were previously monitored and studied in California’s reservoirs, but research on the algae in river systems is in its early stages. Most known research on this type of algae has come out of New Zealand, Genzoli said.  

“We never thought about this stuff growing in the river,” she said.  

In August, Lake Mary Ronan, just west of Rollins, had a significant bloom of Oscillatoria, another type of blue-green algae that produces cyanotoxins. Water samples from the northeast shoreline included cyanotoxin.  

The algae stick to the bottom of rivers, attaching to sediment, rocks or chunks of wood. 

“Cyanobacteria are natural, they are part of the ecosystem, they tend to spread really easily on their own. They're not an invasive species, they aren’t inherently bad... but when there’s a lot of them, they can cause problems, and when there is a lot of them producing toxins then it poses a public health risk,” Genzoli said.  

The greatest health risk at this time, Genzoli said, would be to dogs or other animals who spend time in the water. When ingested, cyanobacterial toxins can cause illness and even death; monitoring animals and not letting them eat any type of algae is the best way to avoid them getting sick.  

“Poisoning from anatoxin requires eating a large amount of algal material,” Genzoli said in a press release. “Which is why dogs and, in some cases, small children are at the biggest risk. Fortunately, it generally requires ingesting a lot of algae to harm people and animals, so most of the risk can be mitigated by watching small kids and dogs closely and not letting them drink or play in areas with attached or floating mats of algae.”   

The algae are only toxic if consumed and once released into the water from the algae, the toxins cannot survive long.  

The California study involved visual surveys, cyanobacteria-dominated mat samples and water samples. Resulting data revealed widespread prevalence of the toxins throughout the middle and lower Klamath River watershed, pointing toward the reality that the toxin could be more common than previously thought.  

Genzoli looks forward to continuing her research on toxic algae, with the goal of learning if it's linked to climate change and if the algal blooms exist regionally.  

The recent study, completed by the Biological Station and the Karuk Tribe of Northern California, was published in the scientific journal Freshwater Science.  

“There's this question of like, is this stuff expanding or are we just starting to pay more attention? And that’s a complete unknown,” she said.  

Reporter Kate Heston can be reached at kheston@dailyinterlake.com or 758-4459.