DEQ investigates algae growth on Smith River

Algae forms on the Smith River. Photo courtesy Montana DEQ.

HELENA – A long, coarse algae is showing up on the Smith River in greater quantities than ever before. Now, the Montana Department of Environmental Quality is trying to figure out why.

Neighbors along the Smith River first alerted Montana Fish, Wildlife and Parks about the growing algae back in 2015.

Two years later at the request of FWP, DEQ started sampling the water on the Smith River last August and detected what Water Quality Specialist Chace Bell believes is Cladophora, a type of algae that can impact aquatic life and be a nuisance for recreationists.

DEQ plans to ramp up its testing efforts to figure out what’s causing the growth. Factors like water temperature, stream flow and water nutrients can impact the growth of the algae.

According to water quality experts, if the concentration of Cladophora become too high, the algae can deprive the water of oxygen and possibly kill fish as well as create an eyesore for floaters on the popular waterway.

In the meantime, people who have homes in the area worry this could be indicative of bigger problems. Warren Hopper owns a cabin with his wife along the Smith River and started noticing the algae in the last few years.

“To me it’s alarming because I don’t know what it says about the health of the river system itself,” Hopper said.

Photos courtesy of DEQ


Hopper said he’s been recreating on the Smith River for decades and this type of algae is extremely rare.

“Something is changing. That isn’t there every year. It’s been there now for two or three years running. It’s a change I would like to know the underpinnings of,” Hopper said.

DEQ hosted its first informational meeting about the issue on Wednesday and is hoping to gain community feedback about the algae. As DEQ gathers the necessary scientific data and community feedback, the agency will look at management options to help prevent the algae from growing.