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Reducing the Risk of Wildlife Collisions

Frequently Asked Questions

How many collisions with animals are reported on Washington’s highways each year?

Each year more than 1100 wildlife/vehicle collisions are reported to the Washington State Patrol (WSP). It’s apparent that not all collisions with wildlife are reported since WSDOT removes an average of nearly 3500 deer and elk carcasses from Washington highways annually.

These collisions result in an average of 1190 human injures and two fatalities per year.

Why are collisions with wildlife a concern for WSDOT?

Elk crossing SR 504 photo
Elk crossing State Route 504 in Cowlitz County.

WSDOT works to reduce the severity and frequency of collisions on state highways to the extent that is reasonable. Although we cannot control wildlife behavior or movements, we can identify locations with high wildlife /vehicle collision rates. These locations may indicate areas where highways cross significant wildlife-use areas, such as deer or elk wintering areas or migration routes. These areas need to be taken into consideration when managing the highway system. Collisions with wildlife can also reduce wildlife populations, which can be a concern for rare or sensitive species.


What areas of the state have the highest numbers of road kill?

Photo of Big Horn Sheep Crossing US 97
Big Horn sheep cross US 97-A near Rocky Reach dam, north of Wenatchee.

High numbers of wildlife/vehicle collisions frequently occur in areas where large numbers of deer and elk are present, directly adjacent to high-traffic-volume highway segments. Areas with some of the state's highest wildlife/vehicle collision rates are:

Eastern Washington - State highways in the Spokane area, particularly north of Spokane, where the highways intersect with white-tailed deer wintering grounds.

State highways in the Methow River Valley, that host one of the state’s most prolific mule deer herds, consistently have high numbers of animals killed in collisions each year.

The abundant mule deer population in the Wenatchee vicinity results in high deer collision rates on the busy highways both north and west of the city. On U.S. 97, there are high deer/vehicle collision areas just north of Goldendale and to the north between Omak and Tonasket. The highest number of elk/vehicle collisions that occur in eastern Washington is on Interstate 90 near the Easton/Cle Elum vicinity.

Western Washington – Deer and elk/vehicle collisions are more widely distributed on the west side of the Cascade Mountains, but there is a high rate of deer/vehicle collisions on Whidbey Island, along State Route 20 and State Route 525. High numbers of elk/vehicle collisions have occurred in the Packwood-Randle vicinity on U.S. 12, and on Interstate 90 near North Bend. 


What animals are most often involved in vehicle collisions?

Photo of black bear along the Mount Baker Highway SR (542)
Black bear are spotted along the Mount Baker Highway (SR 542) in Whatcom County

Most reported wildlife/vehicle collisions are with deer and elk. Each year there are a few collisions with other large mammals such as moose, bighorn sheep, cougar and black bear.

The more commonly killed smaller species are raccoons, coyotes, squirrels, rabbits, opossums, frogs, salamanders, and snakes.

What are we doing to reduce the risk of collisions with animals that wander onto the highway?

Photo of Deer Crossing Sign
Deer-crossing signs with flashing beacons have shown to be effective in warning moterists of the potential for animals on the road.

An effective method for reducing the risk of wildlife collisions is to use 8-foot high wildlife fencing to prevent animals from entering the highway. Wildlife fencing has been installed in a few key areas such as along Interstate 90 east of Cle Elum. However fencing is expensive to install and maintain and cannot be used everywhere.

Signs are the most commonly used tool to warn motorists of the possibility of wildlife on the highway. Signs are installed in areas with documented high numbers of deer or elk/vehicle collisions. Flashing signs, or signs with regularly updated messages, are more successful at reducing deer or elk/vehicle collisions then regular signs and are used in areas with high wildlife/vehicle collision rates. 


What is WSDOT doing to help protect wildlife?

WSDOT is working with the Department of Fish and Wildlife and other stakeholders on a statewide habitat connectivity assessment that will identify areas where wildlife require movement across the highway.
In addition to this planning work, WSDOT is incorporating wildlife protection measures in its projects. One example is a new project that is just beginning construction, the Interstate 90, Hyak to Easton project, which has a number of wildlife crossing structures and wildlife fencing.

There are other examples, such as the recently completed wildlife crossing underpass on SR 240 that provides access to habitat in the vicinity of McNary National Wildlife Refuge, the bridge at Casey Ponds, on U.S. 12, which was built with an increased span to accommodate wildlife crossings along the water’s edge, and the wildlife fence on US 97A.

If you install a fence, won’t the animals just cross the highway at another location?

Highly motivated wildlife will find their way around the ends of fenced highway segments, especially if there are no built-in crossing structures. However, combining fencing with suitable crossing structures (wildlife over- or under-passes), reduces the tendency for animals to run around the end of the fences as they learn to use these crossing structures to pass safely to the other side of the road.

What technology or devices has WSDOT considered to reduce road kill?

WSDOT has evaluated a number of different technologies for reducing road kill. These included deer reflectors, a laser detection system and animal activated warning signs. Unfortunately most of these have not proven to be effective. The only method still in use is the animal activated warning signs that are used to notify motorists when the elk cross the highway in Sequim. This system has been in place since 2000 and relies on radio telemetry collars that have been placed on several elk to trigger a flashing elk crossing sign. While the system has reduced the number of elk/vehicle collisions, it has several drawbacks including the need to place radio collars on the elk, and false warnings that are triggered when the elk are near the sign, but not necessarily crossing the road.

Why doesn’t WSDOT just lower the speed limit in areas where animals are known to cross the highway?

While lowered speed limits may help reduce the number of wildlife/vehicle collisions, it is difficult to get drivers to comply with the lowered limits. If drivers feel that the lowered speed limit is unreasonable, then they are likely to engage in passing, tailgating and speeding, which can increase the severity and frequency of collisions. 

Who is responsible for removing dead animals from the highway?

WSDOT maintenance workers remove animal carcasses from state highways. In many areas this work is done exclusively on week days.

What happens to the carcasses?

In most areas, carcasses are buried at designated disposal sites. Freshly killed animals are sometimes donated to local Indian tribes. In a few areas of the state, where abundant road kill is a chronic problem, the carcasses are taken to a permitted composting facility. 


Contact: Kelly McAllister, Fish and Wildlife Biologist, WSDOT Environmental Services, 360-705-7426,