WSDOT crews began clearing Chinook and Cayuse passes on Wednesday, March 1. We aim to reopen both Chinook and Cayuse passes Memorial Day weekend (Cayuse usually reopens first). However, we are seeing more snowfall than average this year so our clearing work could hamper our target date. Drivers can now sign up for email alerts for US 12/White Pass, SR 410/Chinook Pass and SR 123/Cayuse Pass. After entering their email address, subscribers should check the box for "Mount Rainier Area State Highway News" under the "News and Information" section of the page.
Thursday, April 20:
Cayuse Pass: Crews dealt with heavy snowfall on a daily basis this past week. At last check today, our crews are beginning to head down SR 123 near the Cayuse summit and are working in in various depths of snow.
Chinook Pass: The additional snow and occasional sunbreaks helped crews get some avalanche control work done on Chinook Pass this week. But this also created challenges for maintenance crews.
Chinook and Cayuse passes provide travelers two scenic routes through the Cascade Mountain range in Washington that take visitors through Mount Rainier National Park.
Chinook Pass, the east entrance to the park, is located three miles east of Cayuse Pass and 51 miles west of Naches on SR 410. It has an elevation of 5,430 feet.
Cayuse Pass is located at the junction of SR 123 and SR 410 which is approximately 21 miles east of Greenwater on SR 410 and 16 miles north of US 12. It has an elevation of 4,675 feet.
Chinook and Cayuse passes close every fall due to avalanche danger, poor road conditions, lack of snow storage and no emergency response services within close proximity. All of these concerns make travel hazardous for the public as well as maintenance crews. The safest approach to managing these passes is to simply close the roads once winter conditions warrant the need.
In addition, both passes rely on the National Park Service (NPS) emergency and summer seasonal staff to monitor the roadways. There is a shortage of staffing during the winter months.
Chinook and Cayuse passes close in late November and open around Memorial Day weekend in the spring.
During seasonal closures, Crystal Mountain can be accessed from Enumclaw on SR 410, but not from the east side of Chinook Pass. White Pass can be accessed from US 12, but not SR 123.
On average maintenance crews clear over 30 miles of snow on the two passes. Crews use bulldozers and snow blowers to remove snow 30 feet deep or more from the roadways. It takes approximately 3,000 crew hours over a four to six-week period to clear more than two billion cubic yards of snow in order to reopen Chinook and Cayuse passes each year.
To help reduce the danger of hazardous avalanches during the clearing process, trained crews knock down snow using up to 1,600 pounds of explosives. Avalanche control with the use of explosives is rarely performed in Mount Rainier National Park to avoid damage to natural resources, historic roads and to protect the federally designated wilderness.
Opening and closing Chinook and Cayuse passes requires coordination between WSDOT, NPS and the Washington State Patrol. The NPS hires WSDOT to clear the snow within the park boundary. WSDOT also repairs the highways and posts signage. The NPS patrols the state highways inside the park, provides staffing and other recreational amenities. WSP patrols the highways outside the park.
Safety is our number one priority and the passes do not reopen for the season until WSDOT, NPS and WSP agree to do so.
Drivers can now sign up for email alerts for US 12/White Pass, SR 410/Chinook Pass and SR 123/Cayuse Pass. After entering their email address, subscribers should check the box for "Mount Rainier Area State Highway News" under the "News and Information" section of the page.