Restoring living history, the Bonneville cutthroat trout, in Mill Creek, UT

Many of the places where we live have a long history of human development, which are preserved in history by landmarks, museums and monuments.  A little known source of history and heritage, but not so easily preserved with monuments, are the ecological relicts that existed in these places for millennia before they were settled by people.  These ecological relicts are so quickly and easily erased from the landscape.  This story highlights a small victory for one ecological relict or piece of living history, the Bonneville cutthroat trout in Millcreek Utah.  Millcreek, a community located just to the southeast of Salt Lake City, is embedded as a historical icon in the Salt Lake Valley.  The stream Mill Creek was named after the first flour mill in the Salt Lake Valley, which was built on the banks of Mill Creek to become the primary source of refined flour and other grains for the local population in 1849.  One of the old mill stones still exists as part of a monument to remember this history in the community of Millcreek.  The heavily wooded canyon also provided much needed lumber for the communities.  It is reported that, at one point in time, up to 20 sawmills were in operation in Mill Creek Canyon.  Over time as technology improved, our reliance upon water-driven mills diminished.  None of the historical mills stand today, but the history remains. 

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A map showing the Mill Creek restoration project area. (Image courtesy of the Utah Division of Wildlife Resource).

During the time period of early development in the Salt Lake Valley, all of the small and large streams that drain the Wasatch Mountains on the east side of Salt Lake City became the sole source of much-needed water and food for the new communities.  Many of these streams were quickly dewatered to produce agricultural crops and the native trout, the Bonneville cutthroat trout, experienced heavy overfishing because they provided a provisional food source in times of need.  During this period of settlement, the technology did not exist to develop native trout strains in hatcheries, so exotic fish species such as brown trout and rainbow trout were imported into our streams to replace the diminished native fisheries.  Little by little, each stream lost their living history, the Bonneville cutthroat trout, which had persisted for 10’s of thousands of years prior to European settlement. 

In October 2014, Utah Division of Wildlife Resources (DWR) released 3,000, 2-to-3-inch native cutthroat trout in the upper third of Mill Creek, and for the first time in almost 100 years, indigenous Bonneville cutthroat trout once again swim in Mill Creek.  This event was a culmination of a multiple year cooperative effort led by a broad range of partners including the Stonefly Society (Trout Unlimited’s chapter in Salt Lake City), the Uinta-Wasatch-Cache National Forest, the Utah Division of Wildlife Resources, PacifiCorp and the Boy Scouts of America.  Until last October, only a handful of small streams along the Wasatch Front supported our only remaining native trout populations. 

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One of the reconstructed culverts on Mill Creek.

Removing exotic species and reintroducing the native Bonneville cutthroat trout into Mill Creek has been a very complex proposal.  Due to its proximity to the Salt Lake City metro area and the high intensity of recreational use the watershed receives, restoring a native fish population is no small task.  In order to restore and reintroduce native trout, the exotic species must first be removed.  A piscicide, known as rotenone is the most effective method to remove all fish from a stream system.  Because rotenone kills all the fish in the stream and treatment needs to occur over two successive years, extensive planning has occurred.  The Utah Division of Wildlife Resources, the lead partner on the nononnative removal project, has phased exotic species removal by breaking the stream up into sections.  Using existing upstream migration barriers the exotic species removal has occurred starting at the headwaters and then moving downstream.  

During 2013 and 2014, in conjunction with the nonnative removal, the State Council of TU and the Stonefly Society played a pivotal role in the removal of three barriers by replacing undersized road culverts and removing an old bridge in the headwaters of Mill Creek.  With the help of an Embrace-A-Stream grant funded by Orvis through their 1000 Miles Initiative, the Stonefly Society provided funds to replace the culverts to allow fish passage and reconnect the headwater habitat.  TU volunteers also contributed 100’s of hours to the project by assisting in cleanup and disposal of non-native fish after rotenone treatments. Two rotenone treatments have been completed in 2013 and 2104 with two more treatments planned for 2015 and 2016.  

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 Bonneville cutthroat trout being stocked into Mill Creek. 

In continued support of the remaining rotenone treatments, Stonefly Society members hope to remove a human-made waterfall in the middle of the Canyon, which acts as a fish migration barrier.  After all of the exotic trout and barriers have been removed from Mill Creek, it will be an example of how human development can be compatible with the native fish that represent the rich ecological history of the region. 

A local TV crew asked a TU volunteer why the Bonneville cutthroat trout was more valuable in this particular creek than other trout. The answer; “Because there is something aesthetic and even moral about catching a trout that evolved in and rightfully belongs in this creek.”

Special thanks to the following supporters on this project:

• Utah Division of Wildlife Resources
• U.S. Forest Service
• U.S. Fish and Wildlife Service
• PacificCorp
• Great Salt Lake Council of the Boy Scouts of America
• Wasatch Watershed Legacy Partnership
• The Orvis Company
• Utah Council of Trout Unlimited
• Stonefly Society
• Utah Anglers Coalition
• Bonneville Cutthroat Trout Conservation Team
• National Forest Foundation