The river was altered by the 1980 eruption of Mount St. Helens , a nearby volcano , and subsequent flows of ash and other debris . It was further altered by dredging to remove sediment , and by construction of the Toutle River Sediment Retention Structure on the North Fork Toutle River
1980 eruption of Mount St. Helens
1980 eruption of Mount St. Helens
Toutle River