The Freedom to Move: Why Wildlife Crossings on I-5 Matter

By Brian Stewart, Cascades to Olympics Program Manager

When the world changes, survival depends on more than just resilience—for people and wildlife, it means having the freedom to move. Movement has always been a vital part of adaptation, allowing species to leave behind harsh or unlivable conditions in search of better ones. Throughout history, this ability to migrate across the landscape has helped humans and animals avoid extinction during climate upheaval, food scarcity, or dwindling chances to reproduce.

While natural barriers like mountains and oceans have historically limited wildlife movement, today’s challenges increasingly come from anthropogenic barriers- development, fencing, and large highways- that fragment habitat and stifle connectivity. Across Washington, roads and highways fragment wildlife habitat, disrupting natural migration routes and causing unnecessary animal deaths and vehicle collisions. These crashes harm wildlife and cost taxpayers millions of dollars annually in damages, injuries, and emergency response.

The most striking example is Interstate 5, the largest and busiest roadway in the state. This corridor of speeding cars, concrete barriers, and steel fencing forms an almost impenetrable wall for wildlife. The sheer scale and intensity of the highway create a psychological boundary just as much as a physical one. Those animals that do attempt to cross it face high mortality rates; others have learned to avoid it altogether.

But avoidance isn’t the same as adaptation. I-5 severs habitat corridors and prevents wildlife from reaching seasonal ranges, new food sources or potential mates. Over time, this isolation has led to fragmented populations with reduced genetic diversity, representing a population-level threat. Wildlife, including cougars, elk, and even amphibians, have been marooned on ecological islands, cut off from others of their kind, often within sight of a habitat they can no longer reach.

A Crisis in Search of a Solution

The impermeability of I-5 affects us all, and addressing it will require broad collaboration. Since 2016, stakeholders, agencies, and conservation groups have been working to solve this critical connectivity challenge. But it wasn’t until 2022 that a unified path forward began to take shape. Today, Conservation Northwest is working alongside the Washington State Department of Transportation, Tribal nations, and a wide range of partners, united by a shared vision for reconnecting habitat across this major highway. The first step was completing a collaborative feasibility study, identifying potential locations where wildlife crossings could one day bridge this divide. The study, using scientific data and modeling, articulated two specific areas to focus on- a northern linkage in Thurston County and a southern linkage in Cowlitz County. These are the last, best hope for restoring habitat connectivity along the I-5 corridor throughout Washington. With these linkages defined, the study also examined construction feasibility, cost estimates, and potential design approaches to guide future investments in wildlife crossings. But this is more than a report; it’s a roadmap and a beacon of hope that, through commitment and collaboration, we can restore this ecological cornerstone to benefit Washington’s people and wildlife.

Looking forward, Conservation Northwest continues to work closely with the Washington State Department of Transportation and its habitat connectivity biologists, but science alone cannot repair this landscape. It will take political leadership, public awareness, and dedicated funding. With landmark efforts like the I-90 Wildlife Crossings, Washington once led the nation in restoring landscapes for wildlife. But as other states build on that momentum, we risk falling behind unless we renew our commitment to bold, science-driven solutions. The window of opportunity is narrowing and the time to act is now.

Conservation Northwest has always worked for a wilder future, and even though I-5 cuts through some of the most developed parts of the state, we can’t reach that vision without addressing its ecological impact. Imagine a future where elk, cougar, and, someday, even wolves can move safely across this major highway, free to roam and reclaim wild ground in the Cascades and Olympics. It’s a legacy we can build for future generations, a Washington where people and wildlife thrive side by side. By centering our next steps in science and shared values, the feasibility study sets the stage for transformative action. The study may be the first step on this journey, but it lays the groundwork for what’s possible when science, collaboration, and determination come together.