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 estimated at roughly 24,000,000 cubic yards (about 33,000,000 tons) and said reshaped channels and floodplain habitats. Staff said the new maps are intended to align county shoreline and critical-area guidance with post-removal river conditions and to inform permitting decisions where property owners must demonstrate a construction will survive a specified planning horizon or meet geotechnical standards.

"When you have good information, that's important," a county staff member told commissioners, adding that the maps are guidance and that landowners can challenge a designation with site-specific studies if they disagree. The county said consultants who prepared the maps included specialists in hydraulic and geomorphic analysis; staff also said the maps will be made available for public review and that the Board of County Commissioners will open a public hearing on June 3 with a written comment period staying open until July 8.

During public comment, homeowner Anne Anderson of South Shore Road at Lake Sutherland described shoreline and structural damage she attributed to powerful waves from wake-surfing boats. "The powerful waves generated from these boats are really creating a lot of damage," Anderson said, listing eroded shorelines, sinking bulkheads, loosened dock pilings and concerns about disturbed fish spawning habitat and invasive-species ballast-water transfers.

County staff and commissioners discussed enforcement and regulatory roles. A county official noted that boat operators are responsible for damage caused by wakes and that enforcement depends on the waterbody and the agency: the U.S. Coast Guard covers certain federal waters; local law enforcement enforces inland waters. Staff said Lake Sutherland has existing no-wake buoys in some areas and confirmed that county code and the shoreline master program provide a regulatory interest in protecting shorelines, but that the county lacks direct law-enforcement authority to police recreational activity and would need coordination with the sheriff and the Board of County Commissioners to pursue ordinance or enforcement changes.

Residents and commissioners also asked technical questions about whether the river had reached a "new normal" since dam removal; staff said consultants assessed historic imagery, lidar and hydraulic modeling and judged the river to be relatively stable but acknowledged ongoing dynamics and uncertainty tied to future flood events. The presentation included reference to engineered log jams and restoration structures placed in the lower river; staff said the hydrodynamic effects of many log jams are still being studied and that the mapping represents the best available data at this time.

Staff asked the commission to help inform the public and noted the Department of Ecology grant ends June 30; the county intends to present the maps to the Board of County Commissioners for a resolution to guide use of the maps as best-available science without immediately changing regulatory standards in the Shoreline Master Program.