Photo: NPS

Lake McDonald in Glacier National Park is renowned for many reasons. At ten miles long and nearly 500 feet deep, it’s the largest lake in the park and offers stunning clarity, colorful rocks, and sweeping views that provide a glimpse into the park’s rugged interior. Due to its close proximity to the park’s west entrance, the lake is a popular stop for visitors, and the view from the foot of the lake is arguably one of the most photographed places in the park.

Glacier National Park is characterized by its relatively untouched wilderness and pristine waterways, and park staff have identified a great need to identify the presence of microplastics and make informed decisions about how this pollution could be affecting the park’s waterways now and in the future.

This is the first time the park has evaluated any of its waters for the presence of microplastics. Keep reading to learn about some of the results and findings from this initial study in Glacier National Park. Your donations to the Glacier Conservancy are making this research possible!

Microplastics Study the first of its kind in Glacier National Park

You may have already heard of microplastics – the tiny fragments from larger plastic items that continue to break down until they’re small enough to infiltrate waterways, food systems, and even enter our bodies.

Marine environments have been the focus of many microplastics studies, but we’re learning that much of the plastic can enter oceans through the world’s freshwater rivers.

A study in Yellowstone Lake in Yellowstone National Park determined that microplastics have entered the aquatic foodweb. Concerns that Lake McDonald in Glacier National Park could also be contaminated with microplastics prompted this pilot study to determine if microplastics exist in the lake and, if microplastics exist, the relative scale of the contamination.

The sun sets behind a mountain range with an alpine lake in the foreground

Photo: NPS

A 1km grid map of Lake McDonald used to select random sites for microplastics sampling. 

Student Intern Returns to Glacier to help with Microplastics Study

You may remember Brandon Barnes, the Flathead Valley Community College student and fisheries intern in Glacier National Park who worked in the park during the summer of 2020. You can read more about his work and how donations to the Glacier Conservancy made the internship possible here.

This summer, Brandon returned to Glacier as a Fisheries Technician Intern, and much of his work centered on waterborne microplastics research on Lake McDonald.

The pilot study involved a total of 40 sample sites across the lake. The team retrieved the samples from each site using a micron plankton net dropped to a depth of 20 meters, collecting any plankton, debris and potential microplastics along the way.

Storing each sample separately, these samples were then brought back to the office to be filtered and dried overnight so the team could then analyze them under a microscope.

According to a report provided by the team, “suspected microplastics were defined as particles <5mm in diameter or length (Driscoll et al. 2021) that appeared as colored threads or particles under the microscope.”

If the team came across a suspected microplastic, they also used the “hot needle test” to see if the sample reacted to heat by curling and melting under the scope, thus indicating it was plastic.

A team of scientists stand along the shore of a river in mountainous backcountry

Photo: Brandon Barnes

Brandon Barnes, the Fisheries Technician Intern for Glacier National Park, sorts through dried samples from Lake McDonald in search for microplastics. 

A team of scientists inspect a backpack on a crew member while wading in a river

Photo: Brandon Barnes

The team deploys plankton nets to gather samples from Lake McDonald. They will then take the samples back to the lab and assess for the presence of microplastics.

A raft packed with crates of supplies sits along a river shore in the mountains

Photo: Brandon Barnes

Retrieving the plankton nets involve decanting off much of the water to concentrate the sample. 

Results and Findings in Glacier’s First Microplastics Study

Although the park sampled a small fraction of the lake’s total volume, the team did find evidence of microplastic pollution in their samples from Lake McDonald. Most of the microplastics were small pieces of fibrous materials, along with what appeared to be a fragment of monofilament fishing line.

So, what comes next? According to the park’s initial report on the study:

The ecological implications of our sampling are less clear. Questions remain as to whether these particles continue to break down into ever smaller and smaller, inert particles concentrated on the lake bottom, how much exits the lake into the larger Flathead River system, and do they end up in the ecological food-chain causing adverse impacts to the ecosystem or harm to individuals?

These questions are beyond the scope of this initial study, and ecological impacts remain open to investigation. Right now, there are more questions than answers when it comes to microplastics in Glacier National Park, and we’re just beginning to identify the pieces of this complicated puzzle.

One thing is clear. According to the park’s report, “It’s reasonable to conclude that we should be doing all we can to dispose of plastics properly and keep them out of the natural environment.”

Your Support Makes A Difference

This project and many other critical projects would not be possible without your donations to the Glacier Conservancy.

Learn more about how your support is making other projects possible in Glacier National Park!