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South Coldwater Slide Information

On Sunday evening, May 14, 2023, around 9 p.m. a saturated deposit of material from the 1980 volcanic eruption of Mount St. Helens gave rise to a gravity-driven debris flow that released thousands of tons of debris into South Coldwater Creek.

The debris flow, referred to as the South Coldwater Slide, caused significant damage to the upper portion of State Route (SR) 504 near milepost 49 leading up to the Johnston Ridge Observatory north of Mount St. Helens. The event followed a recent warming trend and significant snowmelt that had saturated the ground. The debris flow washed out the Spirit Lake Outlet Bridge, an 85-foot structure, damaged the roadway, and severed power to Johnston Ridge Observatory. 

Recreation Information

Last updated May 19th, 2025