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.
There are an estimated one to two million collisions between cars and large animals every year in the United States, costing society over $9 billion annually in vehicle repairs, injuries, and road cleanup. Studies show that well-designed wildlife crossings can decrease wildlife-vehicle collisions by up to 97%.
Each year, a talented team of experts embark on the Wildlife Crossings Across America Road Trip – an immersive expedition across the country and beyond to raise awareness about the need for wildlife crossings and connectivity in critical regions.
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.