Sediment Sampling on the North Fork Toutle River, WA

Wading into the North Fork Toutle River above the Sediment Retention Structure (SRS), Tami Christianson collects a water sample from mid-stream. Millions of cubic yards of sediment from the May 18, 1980 debris avalanche have been transported downstream, creating flood risks for communities and damaging fish habitat. The SRS (not pictured) is designed to trap the sand-sized sediment closer to the volcano to reduce downstream impacts. Sampling above and below the SRS is done periodically to evaluate sediment size and concentration to determine if the structure is working as designed.