Brooke shows off some samples collected in Lake McDonald.

For many visitors, Lake McDonald serves as a welcome to Glacier National Park – and what a welcome it is. At just over 10 miles long and 464 feet deep, Lake McDonald is both Glacier’s longest and deepest lake. Looking across the crystal-clear water from the dock at Apgar Village, the stunning backdrop to this iconic lake includes some of Glacier’s most rugged peaks. People come from all over the world to see and photograph that view, that water, and, on a sunny day, the colorful rocks that create the shoreline. Given the popularity, accessibility, and importance of the lakes in Glacier, one might think there is a long-established lake monitoring program in the park. One would be wrong.

That’s not to say there aren’t people watching, studying, and researching—but a formal lake monitoring program does not exist because there is no federal funding for one. Nevertheless, NPS staff are committed to monitoring the park’s waters and acting as needed. That is precisely why Chris Downs, Glacier’s Aquatic Programs Manager, requested a Conservancy-funded study to determine the cause of concerning levels of phosphorus and nitrogen in Lake McDonald.

Brook and John doing research on Lake McDonald.

Brooke and Jon doing research on Lake McDonald.

The 2-year study includes sampling water from Lake McDonald and its tributaries to determine how much phosphorus and nitrogen entered, was stored in, and left the lake. Through this nutrient accounting process, researchers would look not only at the levels of nutrients in Lake McDonald, but also where they originate. In addition, a lake sediment core would be collected to evaluate nutrient inputs and changes in lake productivity over the last approximately 150 years.

A lake sediment core is collected using a weighted tube-like instrument that captures a vertical cross-section of the bottom of the lake. The core is sliced into smaller disc-shaped samples to analyze nutrients and algal remains at different moments in time. Lastly, an important takeaway from this project would be the development of a long-term lake monitoring plan for Glacier.

Enter University of Montana Ph.D. student Brooke Bannerman. Brooke is equal parts dedicated scientist and your-favorite-teacher-ever. Meaning she’s wicked smart and diligent about the process. She’s also patient and enthusiastic about sharing her expertise with others. Brooke will tell you she loves lakes. “Deep, cold lakes. Mountain lakes,” she says with a smile.

Two scientists handling a lake core.

A sediment core collected from the bottom of the lake.

Why does Brooke feel so strongly about these lakes? “Deep, cold, clear mountain lakes are inspiringly beautiful features on the landscape,” she explains, “and when ecological changes occur in a lake, those changes are most often caused by something significant. The lakes tell a story.”

September 18th is Brooke’s last day of sampling for the Lake McDonald project and I am excited to join her to get a closer look at this critical project. It is overcast but mild. Brooke recounts a gnarly day at the end of August when she hiked to Snyder Lake, a tributary of Lake McDonald, for sampling. The entire day was a downpour and she was close to hypothermic by the time she returned to her 4Runner. Tributary sampling typically involves a pack raft and as Brooke says, “a circus act with her instruments to ensure clean samples.” This work is not for the weak, that’s for sure.

On this last day of sampling, Brooke has a boat provided by NPS and an expert assistant. Jon McCubbin, Fisheries Biologist, has been at Glacier for about 10 years and as Brooke pointed out to him, he was there on her first day of sampling for this project two years prior. Brooke and Jon have an easy comradery, sharing stories from the field and an obvious mutual respect for each other as dedicated scientists. After about 10 minutes and with ¾ of Lake McDonald behind us, Jon stops the boat at a set of GPS coordinates provided by Brooke. We have arrived at a frequently used sampling site.

Brooke using the staw-like device to collect water samples.

Brooke using the staw-like device to collect water samples.

I assist in measuring temperature, dissolved oxygen, and pH levels at varying depths. Water samples are taken using a tool that works like a giant straw. The samples are secured in a cooler and we are off to 10 more sites to repeat the water sampling procedure. After about 4 hours, the first part of Brooke’s day is complete. Next, she will transport the samples to the Flathead Lake Biological Station where she will filter, freeze, and wait. Her filtering and freezing process will take about 7 hours and she may make it home to Missoula by midnight. The scientists at the biological station will analyze Brooke’s samples for concentrations of different compounds containing phosphorus and nitrogen, and Brooke hopes to have her data sometime in January or February of 2024.

So far, there seems to be good news. The data from the first year of the study indicates Lake McDonald’s nutrient levels have returned to historically normal levels. That’s just year one and there is still a lot of work to be done and a lot of data yet to come. Brooke will be the first to say, “This work, this important study, does not happen without Conservancy funding.” Moving forward, and no matter the outcome of this project, she is adamant that a monitoring program can and should be established for the lakes in Glacier. Much like the Conservancy-funded Wilderness Program Data Steward position, wouldn’t it be great if the beloved lakes of Glacier had a dedicated and passionate steward like Brooke to ensure they stay beautiful and pristine for the future?

How can you help water quality monitoring in Glacier?

Este proyecto y muchos otros programas críticos no serían posibles sin sus donaciones a la Conservación de Glacier.

Dona Ahora para apoyar trabajo importante como este en el Parque Nacional Glacier!

Brooke smiling with a smiley face made of mud.
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