Shortly after 9 p.m. Sunday, May 14, more than 300,000 cu. yds. of debris from an adjacent hillside fell approximately 2,000 ft. above SR 504 and covered the roadway with rock, mud, ice and water.
(WSDOT photo)
Following the South Coldwater Slide on State Route 504, also called Spirit Lake Memorial Highway, at Mount St. Helens National Volcanic Monument, initial cleanup work has started.
On Monday, June 26, contractors working for the Washington State Department of Transportation began an emergency contract for slope stabilization, critical site cleanup and reestablishing basic connectivity for SR 504 to the Johnston Ridge Observatory.
This work will help with recovering stranded vehicles, support U.S. Forest Service infrastructure repairs, restore power and fiber communications with Mount St. Helens monitoring instruments and allow engineers to conduct field reconnaissance necessary for designing an eventual permanent solution in the coming years.
Shortly after 9 p.m. Sunday, May 14, more than 300,000 cu. yds. of debris from an adjacent hillside fell approximately 2,000 ft. above SR 504 and covered the roadway with rock, mud, ice and water, causing catastrophic damage to the 85-ft. Spirit Lake Outlet Bridge at milepost 49.
"Recovery work to clear debris and rebuild the bridge at this location will take some time, but we are looking forward to these first few steps," said WSDOT Assistant Regional Administrator for Development and Delivery Devin Reck. "While access to the Johnston Ridge Observatory will not be restored for public use this summer season, we plan on making the most of the fair weather to gather necessary information and begin work to design a permanent solution."
This emergency contract, expected to complete in early August, will create temporary administrative access to the Johnston Ridge Observatory, but the road will not be open to the public this summer. The current closure point for vehicle traffic is the gate located at milepost 45.2, also known as the winter gate. WSDOT annually closes this upper portion of SR 504 at the winter gate each fall because the elevation and geography make it dangerous to clear the roadway. The emergency work is being done by Scarsella Brothers Inc.
Timeline
• May 14, 2023: A debris slide washed out a portion of the highway and bridge at milepost 49.0;
• May 15, 2023: The upper section of SR 504 is closed at milepost 43.0;
• June 16, 2023: Closure point of SR 504 is moved to milepost 54.2, also called the winter gate, and will remain throughout the 2023 summer season.
• June 26, 2023: Emergency contract work begins for initial clean up and vehicle recovery.
Background
In 1980, the north face of Mount St. Helens slid away and triggered a massive eruption that created a lahar, or a slide made up of wet volcanic mud and debris, that devastated the North Fork Toutle River. This event caused extensive damage to approximately 25 mi. of SR 504, including seven of the eight major bridges, leaving only the Kid Valley bridge intact due to its clearance. The segment between Toutle and Kid Valley was buried under 6 feet of sediment, leading to the closure of the highway beyond Toutle. To manage the situation, Weyerhaeuser installed a roadblock and turnaround loop.
Recognizing the significance of this area, the federal government officially designated it as the Mount St. Helens National Volcanic Monument in 1982. Simultaneously, the state government honored the victims of the eruption by designating SR 504 as the Spirit Lake Memorial Highway. To cater to the increasing interest from tourists, a visitor center was established at Silver Lake in 1987. However, the highway remained closed beyond the sediment dam located near milepost 21.
In pursuit of enriching experiences and facilitating greater access to the region, an ambitious construction project for a new highway began in 1988. This undertaking aimed to offer travelers captivating scenic viewpoints along with volcanic educational opportunities. As a result, several notable visitor centers were established along the highway to enhance the overall journey. The Science and Learning Center at Coldwater Creek, situated at milepost 43, opened its doors to the public in 1993, providing a wealth of educational opportunities. Building on this success, the renowned Johnston Ridge Observatory welcomed visitors in 1997. Sitting at the end of SR 504, this unique vantage point is located just in five and a half miles from the crater, which was created after the eruption of the volcano in 1980, and offers wonderful views of the crater and the surrounding area.
These remarkable achievements along with the highway expansion beyond the sediment dam added an impressive 30-mile extension, ultimately reaching milepost 51. This extension not only increased accessibility but also opened up new vistas and opportunities for exploration along the highway.
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