This project proposes replacing the sixty-year-old, undersized Sixmile Creek culvert with two large open-span bridges (east-bound and west-bound). These adjacent open-span bridges will provide an underpass that, when combined with wildlife exclusion fencing to funnel animals to the structure, is a proven tool to reduce wildlife-vehicle collisions (WVCs) while offering suitable and safe crossing opportunities for terrestrial and aquatic species, including elk, deer, grizzly bears, black bears, and native fish. Grizzly bears and elk use open-span bridges or overpasses more readily than underpasses.

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Wildlife fencing along both the east and west bound lanes of I-90 would route animals to the open-span bridges at Sixmile Creek and to two existing bridges over the Clark Fork River to the west. All wildlife fencing will be within MDT right-of-way (ROW), without need for ROW acquisition.

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Additional wildlife features associated with this proposed project include jump-outs, double cattle guards, and electric mats at Huson and Ninemile interstate exchanges. Stream restoration will occur in the project area, as the Sixmile bridges will improve Sixmile Creek by restoring an active channel and bank line.

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Why here?

For decades, public agencies, conservation organizations, and citizens have voiced concern for drivers’ safety and wildlife’s safe passage across Interstate 90 (I-90) in the Ninemile/Sixmile region west of Missoula. This area is a priority location to improve human safety, wildlife movement, and fish passage needs. At least one person lost their life due to a near-collision with wildlife, semi-trucks have toppled to avoid elk, and WVCs have damaged vehicles and killed wildlife in this stretch of I-90. WVCs made up 34% of all reported crashes from 2017-2021 in this section. In September 2025, 11 elk were killed by one semi-truck. 

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The Ninemile/Sixmile is one of the few remaining landscapes in the area where intact forest and riparian corridors provide a network of protected lands to form a movement corridor for multiple wildlife species between large tracts of protected public lands to the north and south. Opportunities for wildlife to safely cross I-90 in this area are currently limited. A large elk herd moves throughout the area, and collared grizzly bears have been documented in this location and surrounding lands. Species listed as threatened or endangered under the Endangered Species Act (ESA) including grizzly bears will benefit from this project through increased movement opportunities and reduced mortality risk.

 

In addition to terrestrial wildlife, native fish are mostly unable to pass through the culvert under the interstate at Sixmile Creek. The culvert has been the top fish passage concern of Region 2 of Montana Fish, Wildlife and Parks (FWP) for over 20 years. There is broad support from the public, agencies, nonprofit organizations and the local community.

 

Public lands are in close proximity along both sides of the highway. Land adjacent to the highway at the culvert location is owned by MDT on one side and is within citizen-initiated zoning which limits future development on the other side, providing a degree of protected status. The adjacent landowner is supportive of the project, as are numerous nearby landowners.

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Where and from whom did this potential project come from?

The Sixmile Wildlife Crossing proposal was submitted by the Western Montana Wildlife Connectivity group (WMWC - formerly Missoula Regional Connectivity Group) to the Montana Wildlife and Transportation Partnership project program and was selected to move forward into an engineering feasibility study phase funded by Montana Department of Transportation. 

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What phase is this project in?

MDT is leading an engineering feasibility study of the proposed project. The study is anticipated to be completed by August 2026. If the project proposal is deemed feasible, then the project can move into design phase but funding will be required to construct the project. ​

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WMWC continues to monitor the potential bridge location as well as the I-90 existing bridges that would be enhanced with wildlife fencing to funnel wildlife to those existing bridges. Wildlife images on this website are from those game camera efforts.  ​

How can I be involved?

WMWC seeks support for this project. We will continue to move the project further in project development, data collection, landowner outreach, public education, and funding.

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