Protecting Yellowstone's Water

Downstream view from the center of a small, clear mountain stream flowing around boulders between gently sloping grassy banks with pine tree forest and mountains in the distance.

Protecting Yellowstone's Water

Yellowstone National Park is a land of pristine rivers and thunderous waterfalls. But a small tributary on its northern boundary once flowed a bright, contaminated orange.

For 80 years, Soda Butte Creek, a tributary of Yellowstone’s Lamar River, carried toxic metals from mining waste downstream into the park.

A small portion of Soda Butte Creek surrounded by green pine trees, willow, and other vegetation. The bed of the stream appears entirely orange in color due to minerals carried by the water from mine tailings and deposited on the stream bed. — (Montana Department of Environmental Quality)

Stream sections just below the mine tailings with the heaviest concentration of metals were lethal to fish.

Map showing the extent of Yellowstone National Park with an inset overview map showing the park's location in northwestern United States. The main map displays major lakes and rivers and the location of the historical McLaren Mine tailings site just outside the northeast entrance to the park.

This is the story of how citizens, scientists, and land managers joined forces to transform Soda Butte Creek from a stream on Montana's impaired waters list to a stronghold for native Yellowstone cutthroat trout.

Close-up view of a large, dark, trout with reddish gills, breaking the water's surface to capture a large, black-legged insect in its mouth.

Water’s connectivity, however, is a double-edged sword.

While its long reach nourishes whole landscapes with moisture and nutrients, it can also spread harm. And this is where the story of Soda Butte Creek comes in.

It is a story about crossing boundaries, but in two starkly different ways.

On the one hand, water flowing across the park boundary with its toxic payload spread harmful conditions downstream for fish and aquatic insects.

On the other hand, scientists, managers, and neighbors collaborating across land ownership boundaries helped restore health to the waters of our nation’s first national park.

Black and white historical photo of a wooden-building lined street with several men standing around or seated on horseback. Mountains rise in the background.

With the fishery gone, orange-colored water staining the stream, and clear evidence of heavy metal contamination in Soda Butte Creek, momentum grew for action.

Orange-colored water pools up and orange-tinted mud coats the lower roots and branches of green, streamside vegetation. — (Montana Department of Environmental Quality)

Two local nonprofits—the Greater Yellowstone Coalition and the Beartooth Alliance—successfully stopped new proposals to expand mining in the area, further protecting the watershed. State and park scientists shared their concerns about the detrimental impact of toxins released downstream of the unstable mill tailings.

And finally, funding from the Department of the Interior’s Office of Surface Mining Reclamation and Enforcement, and Montana’s Department of Natural Resources and Conservation came through for more serious cleanup efforts to go forward.

The first step was gathering a team.

Shaded relief map of Soda Butte Creek showing location of the McLaren Mill site approximately 5 miles outside the boundary of Yellowstone National Park, with land ownership labels visible: Yellowstone National Park; Shoshone National Forest; Custer Gallatin National Forest; State of Montana Land; Park County, Wyoming; Park County, Montana; and the towns of Silver Gate and Cooke City.

Small cluster of warmly dressed people standing outdoors near Soda Butte Creek listening to a man (Tom Henderson) talking to them and gesturing towards the nearby landscape.

Small stream winds through along a deeply entrenched path with a few trees and large patches of barren tailings pile dirt on the slopes above it. Three callout bubbles are overlaid on the image. One callout points to entrenched streambed and reads, “Confined by tailings pile dirt, the stream channel can no longer connect with its adjacent floodplain during high flows. Lacking seasonal replenishment of moisture and nutrients during floods, and buried under piles of tailings dirt, important floodplain habitat is lost.” The next callout points to the orange-colored stream and reads, “High acidity and dissolved metals, like iron, tint the stream water orange.” The last callout points to two piles of dirt near the stream edge and reads, “Highly erodible piles of tailings flank the stream. High flows wash them downstream onto floodplains inside Yellowstone National Park.” — Before restoration (left image, May 2009) and after restoration (right image, August 2016). Ultimately, stream channel engineers moved 1800 feet of Soda Butte Creek back into its historical path and reclaimed its banks. For this work, they won an award in 2015 from the American Council of Engineering Companies.

Same view of the stream path but the stream is now at ground level, no longer entrenched, with medium-sized boulders lining its edge and thick grass covering the surrounding slopes. Four callout bubbles are overlaid on the image. One reads, “Piles of tailings have been removed from the floodplain, solidified, and confined to a repository that is away from surface and groundwater.” The next reads, “The stream channel can now reach and replenish its adjacent floodplain during high flows.” The next reads, “Stream water is clear and no longer contains elevated levels of iron.” The last one, which is next to a small pond adjacent to the stream, reads, “Wet areas, like this small pond, occupy the floodplain outside the stream channel. They provide habitat for dragonflies, amphibians, and other pond-dependent species.” — Before restoration (left image, May 2009) and after restoration (right image, August 2016). Ultimately, stream channel engineers moved 1800 feet of Soda Butte Creek back into its historical path and reclaimed its banks. For this work, they won an award in 2015 from the American Council of Engineering Companies.

Female technician in waders stands in the middle of a shallow stream holding an instrument display panel connected by a thick wire to a long probe inserted underwater.

Topographical map showing the Soda Butte Creek drainage from above Cooke City to several miles downstream past the boundary of Yellowstone National Park. Water quality monitoring sites are labeled as black triangles. The site directly below the tailings pile is SBC-2, and the site at the park boundary is SBC-4.

How well did the cleanup work?

Answering this question presented a couple of challenges. One was to sort out naturally occurring metals in the mineral-rich basin from those related to the mining and milling activities. Another was to provide the State of Montana with the sufficiently rigorous data they’d need to justify any delisting decision for the creek.

With these challenges in mind, NPS scientists from Yellowstone National Park, the Greater Yellowstone Inventory and Monitoring Network, and the Water Resources Division worked with scientists from the state of Montana to design two years of post-cleanup sampling in 2015–2016. They would sample the same sites as in earlier studies for direct comparison, but they needed more than that.

Two technicians wearing life vests and waders stand on the edge of a small mountain stream holding water quality collection equipment. One is inserting a long probe underwater midstream. — Sampling water quality.

Knowing that several tributaries feeding this stretch of Soda Butte Creek might complicate matters with their own mineral loads, scientists added sampling sites in tributaries above their junction with Soda Butte Creek. This helped shape a broader map of metals across the entire basin, revealing that two iron-rich tributaries of Soda Butte Creek downstream of the tailings pile were affecting iron levels at the park boundary.

Accounting for this new basinwide snapshot of background metal levels, the results of the cleanup overall signaled success!

Copper, lead, and manganese no longer exceeded safe limits at any of the sites below the former tailings pile.

This was significant because before reclamation, copper downstream of the mill was still 3.5 to 50 times above the safe level for plants and animals, and even more concentrated in seeps below the tailings pile.

Iron, the culprit behind the bright orange color of contaminated water, decreased to acceptable levels.

Graph of iron concentration in Soda Butte Creek, showing many sample points exceeding the Montana safe limit for iron before 2010, and no sample points exceeding the safe limit after 2014. The period between 2010 and 2014 is shaded and labeled, “Reclamation Period”. An inset map in the corner of the graph shows the location of the monitoring site, SBC-2, immediately downstream of the Tailings Site.

At the park boundary, several miles and tributaries below the former tailings pile, iron still occasionally exceeded limits, but its source was likely the naturally iron-rich waters of two tributaries.

Most importantly, the studies confirmed that the human-caused source of metals from the McLaren Mill site was effectively gone from the stream.

With metals back down to levels safe for aquatic life, the next step was to find out how stream organisms were responding. Studies of aquatic insect populations showed dramatic improvement. NPS Greater Yellowstone Network scientists found that sensitive coldwater-dependent stoneflies, such as Zapada columbiana, and mayflies (in the genus, Cinygmula) were now abundant both above and below the project site.

Aerial photograph showing a large bare dirt opening in the forest next to a town, with a site labeled “SBC-2” next to the opening. At the bottom of the photograph, an image of several brown insects (aquatic invertebrate nymphs) inside a red circle with a red line through it is overlaid onto the aerial photo. — During surveys in 1972–73, before restoration, aquatic insects varied from low to completely absent at monitoring site SBC-2 below the tailings pile. This image (left image), circa 2011, shows mill tailings restoration work underway. After restoration (right image), numerous aquatic insects were found at site SBC-2 in September 2018.

An aerial photo of the same area shown in the previous photo taken after restoration showing the restored Soda Butte Creek stream channel. In the lower right corner of this image large brown rectangle is divided into 21 differently sized boxes, each with a different type of brown insect (aquatic invertebrate nymph) inside it. — During surveys in 1972–73, before restoration, aquatic insects varied from low to completely absent at monitoring site SBC-2 below the tailings pile. This image (left image), circa 2011, shows mill tailings restoration work underway. After restoration (right image), numerous aquatic insects were found at site SBC-2 in September 2018.

An expanded view of the aquatic insects shown in the previous graphic that shows in more detail the microscopic images of the aquatic insects and their common names, such as midges, mayflies, caddisflies, and stoneflies.

Fish were now moving up- and downstream past the once-toxic barrier above Cooke City.

“From this project, we have clean water. Without clean water, restoring the stream community would be moot; no fish, no macroinvertebrates, no life.”

-Brian Ertel, fisheries biologist with Yellowstone National Park

Collage of headlines from four newspaper articles, reading, “State to remove Soda Butte Creek from list of impaired streams” (Bozeman Daily Chronicle); “Event celebrates restoration of soda Butte Creek (Billings Gazette); “Hydrogeologist’s death leaves big shoes to fill in Montana mine cleanups” (Great Falls Tribune); “Legacy of clean water champion endures ‘through the waters he restored’” (Great Falls Tribune).

Shallow, rocky streambed with orange colored water and orange-tinted boulders and woody debris, edged with bright green vegetation. — Before restoration (left, September 2009) and after restoration (right, July 2013).

The same shallow, rocky streambed edged with bright green vegetation, but with clear water and no orange-tint on the boulders or streamside woody debris. — Before restoration (left, September 2009) and after restoration (right, July 2013).

A New Day for Yellowstone Cutthroat Trout

A new opportunity soon emerged. Now that the stream was clean, why not realize the long-held vision of Soda Butte Creek as a stronghold of genetically pure Yellowstone cutthroat trout that once called it home?

Underwater view of a large trout with black spots on brown body, reddish gill area, and reddish stripe along its side. Another trout swims in the background.

Four National Park Service staff in waders and rubber gloves stand in a shallow stream ready to scoop up fish with nets while one of the crewmembers throws an electrified metal tipped pole into the water. The pole is connected to a small boat containing equipment and the electric battery. The photo is captioned, “Electrofishing briefly stuns fish to remove nonnatives or rescue natives.”

Before the cleanup, little appetite existed to use a more aggressive but controversial solution—chemical removal of the fish. Why go through the trouble for a contaminated stream?

The cleanup changed this equation. First, Yellowstone cutthroat trout now had clean water to return to, boosting their chance of survival. Second, relationships that had formed between agency scientists, conservation organizations, and locals during the earlier reclamation project built trust.

A white pickup truck parked on a dirt road with four men gathered around the hood of the truck, conversing in a friendly way. — Sharing a smile with project partners after four years of successful restoration work.

Government scientists had faces and names. And even though the prospect of adding fish-killing chemicals to their newly clean stream concerned local citizens, tense meetings turned to dinner invitations and then to dialogue. Shared understanding, built through relationships, eventually opened the door to moving forward with the project.

Shaded relief map showing the boundary of the Cutthroat Trout Restoration Area, extending from above Cooke City, Montana, down several miles into Yellowstone National Park below a fish barrier, labeled “Ice box Canyon.”

Four smiling men, each wearing a different agency uniform, crouch next to a stream to transfer, by hand, live golden-colored trout into the water from nearby buckets. Caption on the photo reads, “Happy day—releasing Yellowstone cutthroat trout back into Soda Butte Creek in 2016.”

Learn More

Learn about the nuts and bolts of the McLaren Mill tailings pile reclamation project on Soda Butte Creek and see a tribute to its beloved champion, Tom Henderson, through the Montana Department of Environmental Quality’s story map:

https://mtdeq.maps.arcgis.com/apps/Cascade/index.html?appid=7665919d0d024d27badc8029953ff334

Clean pool of water next to a clear-running creek surrounded by grassy fields and forest, overlaid with a title, "Soda Butte Cree Celebration, An environmental success story through mine reclamation."

Learn more about the postreclamation water quality studies: https://www.nps.gov/articles/parkscience34-1_9-21_henderson_et_al_3871.htm

Learn more about NPS Greater Yellowstone Network scientists and the other vital signs they monitor in the region’s parks: https://www.nps.gov/im/gryn/index.htm

Learn more about Yellowstone’s native fishes: https://www.nps.gov/yell/learn/nature/fishaquaticspecies.htm

Learn more about the Yellowstone cutthroat trout: https://mtfwp.maps.arcgis.com/apps/Cascade/index.html?appid=fdf5c7af3413435da2c2190aab5ef9c3

Learn more about water in Yellowstone National Park: https://www.nps.gov/yell/learn/nature/water.htm

The Inventory and Monitoring Division of the National Park Service is like a physician for our parks. We track the health of key vital signs such as water, plants, and wildlife.

Together we can use this information to take care of our national parks for this and future generations.