On the Edge of Wilderness

NorthWestern Energy Biologist Grant Grisak checks a gillnet at Mystic Lake.

By Erin Madison

Reaching Mystic Lake isn’t easy. A bumpy gravel road will get you close, but from the end of the road, it’s another three miles and 1,300 feet of elevation gain to the lake.

Despite its remote location, NorthWestern Energy crews make the trek to the lake sometimes daily, or even multiple times a day during runoff Mystic Lake is home to Mystic Dam, a 12-megawatthydroelectric facility owned by NorthWestern Energy and flanked by the rugged snowcapped peaks of the Beartooth Mountains, southwest of Billings, Montana.

Every three years, members of our environmental team visit Mystic Lake to monitor water quality and fish populations.

Jordan Tollefson, NorthWestern Energy Hydro Compliance Professional, tests the water quality by taking chemical and biological samples from the lake. He looks at microscopic plant and animal life, metals, nutrients, pH, turbidity and more. Typically there aren’t any surprises in the measurements.

“We don’t see much of a change at all,” Jordan said.

And that’s a good thing. It means the lake is staying consistently healthy.

“The water quality doesn’t change because there aren’t many impacts” he said.

That is due in large part to Mystic Lake being surrounded by the Absaroka-Beartooth Wilderness Area. One of the goals of federally designated wilderness areas is to protect watersheds, which means the water flowing into Mystic Lake is some of the freshest and cleanest you’ll find anywhere. It’s the goal of NorthWestern’s Hydro License Compliance team to make sure Mystic remains pristine.

“We monitor on the deepestpart of the lake,” Jordan said. “It’sabout 160 feet deep.”

Jordan Tollefson, NorthWestern Energy Hydro Compliance Professional, collects a water sample from Mystic Lake.

Water samples are taken from various depths in the lake. Mystic Lake is incredibly clear. Water clarity goes down about 15 meters, or almost 50 feet. In comparison, water clarity on the Missouri River near Great Falls is usually 1.5 to 3 feet.

“That’s pretty amazing,” Jordan said. “The wilderness obviously has something to do with it.”

Mystic Dam was built in 1924, 40 years before the Wilderness Act was passed, which gave Congress the ability to create federally designated wilderness areas. In 1978,the Absaroka-Beartooth Wilderness was created, spanning more than937,032 acres, including the mountains and forests surrounding Mystic Lake. The wilderness boundary was drawn to exclude Mystic Lake and Mystic Dam, but just barely. The high-water line of the lake is also the edge of the wilderness area.

The Wilderness Act of 1964 was enacted with the goal of restricting human manipulation on some of the most untouched swaths of public land. Logging and drilling are prohibited in most wilderness areas, as are commercial enterprises, man-made structures, and motorized and mechanized travel. Even chainsaws, wheelbarrows and drones aren’t allowed in wilderness areas.

While the Mystic project is surrounded by a wilderness area ,all the work done by NorthWestern Energy is outside the wilderness boundary. That means we can run the tram, use mechanized tools to work on the dam and perform other work without violating the wilderness protections. Our Hydro License team can even use a motorboat, which was flown in by helicopter, to reach sampling sites on the lake.

Hydro License Compliance Intern Joseph Hagengruber processes water samples at Mystic Dam.

As Jordan takes samples from deeper and deeper in the lake, there’s a dramatic shift in temperature. Mystic Lake is basically divided in half, or stratified. The top half of the lake is warmer and home to fish, zooplankton and phytoplankton. The lower half is cold and dark with little life in it.

“The whole lake shifts in temperature,” Jordan said. “All the warm water just sits above the cold water.”

While the surface of the lake was about 63 degrees last August, it was about 40 degrees near the bottom of the lake.

“It’s super cold water.” Jordan said. “There’s not a lot there.”

However, the warmer, top portion of the lake is home to numerous life forms, including a healthy population of rainbow trout and some cutthroat trout.

NorthWestern Biologist Jon Hanson is in charge of monitoring the fish population in Mystic Lake. Every three years, he sets several nets in specific locations throughout the lake. After leaving the nets overnight, the captured fish are counted, measured and weighed.

“We’re looking to see if there are any changes to the fishery overtime,” Jon said.

Like Mystic’s water quality, the fish population is fairly stable and consistent.

Fishing at Mystic Lake is a popular activity, and rightfully so. The lake boasts an abundant population of rainbow trout in the 9-to-14-inchrange, and fishing can be fantastic during the summer months.

Getting to work at Mystic Lake is a pretty special opportunity, but it comes with challenges, too. With an elevation of 7,600 feet, it snows 12 months a year at the lake.

“It can get pretty hairy up here really quickly,” Jon said.

The Hydro License Compliance group always does their Mystic Lake work in early August, but that doesn’t guarantee summer-like weather. They’ve endured everything from snow to windstorms to sunshine.

Getting to Mystic to do their work is no easy task. From the powerhouse, which sits 1,300 feet below the lake, the group loads all their equipment onto a tram. The open-air tram climbs a set of tracks that seem to go straight up a hillside. At the top, they transfer everything to a small train that runs horizontally along the face of the mountain. A portion of those tracks was washed out decades ago, so a sky crane is used to move gear from one side of the washout to the other. A suspension bridge allows the passengers to cross the deep gully. A final train takes the group to the dam. The whole trip takes about two hours. Three days later, when their work is done, they take the same trip in reverse.

The environmental team only visits Mystic Lake once every three years. However, our Mystic Lake operations crew might make that trek a couple times a day. Sometimes they’ll go weeks without traveling up to the dam, just depending on work that needs to be done.

Technical Advisory Committees

The water quality and fisheries data gathered by the Hydro Compliance Team is compiled into a report and presented to the Mystic Fisheries Technical Advisory Committee.

We have several Technical Advisory Committees, or TACs, that help guide the work we do around our hydro facilities. The FERC licenses that allow us to operate our dams include requirements for the protection, mitigation and enhancement of fisheries, wildlife and habitat resources.

TAC members review progress, discuss and approve projects, and ensure approved projects comply with FERC license requirements.