Clallam County staff present updated channel-migration mapping for Elwha watershed; residents raise wake-surfing shoreline damage concerns

Clallam County habitat staff and consultants presented updated channel-migration-zone (CMZ) mapping for the Elwha watershed and said the maps reflect post-dam-removal changes to the river's floodplain. Staff said the maps will be used as the county's best available science and that the Board of County Commissioners will hold a public hearing on the mapping; residents at the meeting also raised damage and safety concerns from wake-surfing boats on Lake Sutherland.

"Channel migration is a natural process," Rebecca Mahan, habitat biologist for Clallam County, told the commission, describing why the county sought and used a Department of Ecology grant to map the Elwha River, the Little River and Indian Creek. Mahan said the work covered the park boundary downstream and included hydraulics analyses and review of historic imagery.

Mahan and other staff described the context: federal removal of the Elwha dams between 2011 and 2014 released large volumes of sediment into the river system, which the team…