The approach channel shifts continuously, and during our study it has shifted back and forth from the left bank to a course along the right bank nearly parallel to the road.
During the snow- and ice-melt runoff season, which typically extends from mid-May to September, the design discharge for the bridge often is exceeded. Due to a major channel change in 2001, Bridge 339 at Mile 36 of the highway has undergone excessive scour, resulting in damage to its abutments and approaches. Bridges along the Copper River Highway, which traverses the alluvial fan, have been impacted by channel migration. This large, glacier-fed river flows across a wide alluvial fan before it enters the Gulf of Alaska. The Copper River Basin, the sixth largest watershed in Alaska, drains an area of 24,200 square miles.
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