Mammoth US 395 Wildlife Crossings
Saving a historic mule deer migration corridor
“Deer are capital mountaineers, making their way into the heart of the roughest mountains; seeking not only pasturage, but a cool climate, and safe hidden places in which to bring forth their young. . . . The deer climbs all the peaks save the lofty summits above the glaciers, crossing piles of angular boulders, roaring swollen streams, and sheer-walled cañons by fords and passes that would try the nerves of the hardiest mountaineers.” John Muir (1898)
US 395 is the main travel corridor in the Eastern Sierra region of California, and sadly, this scenic byway, because of its popularity, can also be deadly to wildlife.
In Mono County, California, a 10.5-mile segment of US 395 located outside the Town of Mammoth Lakes has been found to contain four wildlife roadkill hotspots and bisects a major migration corridor for two mule deer herds: the Round Valley and the Casa Diablo.
But it’s not just the deer who suffer from the vehicle traffic. Bears (and their cubs) have been killed in the area, along with a host of other wildlife such as mountain lions, coyotes, bobcats, brush rabbits, grey foxes, and threatened species like sage grouse. One of the rarest mammals in the country has been sighted in the area, the Sierra Nevada red fox, and dispersing wolves in California have traveled nearby.
We can make a difference for wildlife. Improvements to connectivity and reduction in wildlife-vehicle collisions through construction of wildlife crossing structures has been shown to be most effective method for achieving this goal. Aquatic species like Lahontan Cutthroat trout also benefit from improvements along creeks by replacing culverts with bridges, like the streambed of the Convict Creek within the project area.
The area has been recognized by CDFW as a Top Priority in their 2022 and 2024 inventory of Wildlife Movement Barrier Priorities and as a Planned Priority in Caltrans’ 2024 inventory of Priority Wildlife Connectivity Barriers. Similarly, the UC Davis Road Ecology Center’s 2023 annual report identifies the region as a top regional roadkill hotspot. It is also identified in the CA Essential Habitat Connectivity Report (2010) and one of the priority sites pursuant to US Department of the Interior Secretarial Order 3362 for migratory ungulates in the State Action Plan for California.
WCF considers this one of the highest priority projects in the state, as it helps ensure a historic migratory path is preserved for mule deer, a species that faces increased challenges in the Sierra Nevada in light of climate change, extreme weather events, and increasing development. This crossing will also provide passage between the Sierra Nevada and open space to the east for an array of species.
The Solution
The Mammoth Lakes US 395 Wildlife Crossings Project will reduce wildlife-vehicle collisions and improve wildlife connectivity by constructing a series of connectivity infrastructure including an overpass at Morrison hill, an underpass at Convict Creek, along with wildlife exclusion fencing and jump outs.
Status
Caltrans was awarded a Wildlife Conservation Board grant for $3.17 million to complete the Project Approval and Environmental document and to complete 30% designed plans. This has been completed as of April 2026. The Wildlife Crossing Fund, with donations from the Donald Slavik Family Foundation and Joann Randall, also conducted an extensive design workshop and review in 2024 and 2025 with the team at Rock Design Associates.
What’s Needed to Complete this project
The next step is to complete final design and engineering, which will cost approximately $11 million. WCF has been engaged fully in this project and there is a clear path to action. We have already raised $1 million toward the final design and engineering phase with a generous contribution from the Wildlife Conservation Network’s California Wildlife Program. Our focus is to secure the additional $10 million in funding ASAP to allow the project to proceed directly into this phase.
While the final plans are being completed, WCF will also work to secure the needed construction funding.
If all targets are met, this project has the potential to break ground in 2-3 years.
Summary of Estimated Construction Costs
Wildlife overpass at Morrison hill: $46.5 million
Wildlife underpass at Convict Creek: $30.5 million
Fencing and Jumpouts
Construction Support (Inspections, etc.): $6.9 million
Total construction costs: $83.9 million
Note: The construction costs for the overpass and underpass are capital costs escalated to the start date of construction, not the current costs. The fencing and jumpouts for both locations are included in these costs.
Project Collaborators
The project is a result of the collaborative efforts of the members of the Eastern Sierra Wildlife Stewardship Team: Bridgeport Indian Colony, Bureau of Land Management, California Deer Association, California Department of Fish and Wildlife, Caltrans District 9, Defenders of Wildlife, Eastern Sierra Land Trust, Inyo County, Inyo County Fish and Game Commission, Los Angeles Department of Water and Power, Mammoth Lakes Trails & Public Access Foundation, Mono County, Mono County Local Transportation Commission, National Wildlife Federation, Rock Design Associates, Town of Mammoth Lakes, US Fish and Wildlife, Wildlands Network, Wildlife Conservation Network, The Wildlife Crossing Fund.
Your Support Can Make a Difference!
Please join us in reconnecting this historic mule deer migration corridor, and making this roadway safer for all wildlife—and people!
With your help, we can start construction in 2-3 years!
To discuss leadership donations, naming opportunities and other recognition,
please contact Beth Pratt at bpratt@wildlifecrossing.org or 209-620-6271.