2023 South Coldwater Slide

On May 14, 2023, a mudslide and debris flow, given the moniker "South Coldwater Slide" by the U.S. Forest Service (USFS),[1] destroyed the 85-foot (26 m) Spirit Lake Outlet Bridge and severed SR 504 northeast of Johnston Ridge Observatory at milepost 49.[4][5] A team composed of USFS staff and volunteers hiked to the observatory to retrieve scientific equipment and supplies so that observation of the volcano could proceed at the Coldwater Science and Learning Center.[7] Washington State Department of Transportation (WSDOT) contractors cleared debris over the highway by July and created a temporary gravel road to access Johnston Ridge for vehicle retrieval and to prepare for reopening in 2024.[11] The interim roadway was washed out in November 2023 after the replacement culverts failed due to heavy rainfall and erosion which was unrelated to the prior South Coldwater Slide event.Delays in temporarily or permanently reopening the bridge and highway for regular use is also due to a combination of the limited construction schedule based on weather, high elevation, and the steep slope of the area.