The Channel Migration Zone assessment and delineation will outline the zone of historical channel migration and potential future channel migration over a timeframe of 100 years. The CMZ delineations will be used for land-use planning decisions; to inform Clallam County’s Shoreline Master Plan and relevant updates to the Critical Areas Ordinance; and for restoration project planning. In all watersheds, the CMZ’s are found in lower reaches, which also are the most productive salmonid habitat and the first to develop. Floodplain modifications invariably follow floodplain development. Without CMZ delineations, the County cannot effectively protect this productive riverine habitat. CMZ mapping and delineation would occur for McDonald Creek, Siebert Creek, Morse Creek, Elwha River, Salt Creek, Lyre River, East and West Twin Rivers, Deep Creek, Pysht River, Clallam River, and Sekiu River.
This information will provide technical information to local officials and stakeholders to better inform their management decisions related to channel migration hazards along rivers. The project will also be important as an educational tool to increase public and landowner awareness of probable channel movements and erosion in the next five to ten decades.
Methodology would follow Department of Ecology guidelines where aerial photos can identify channel patterns, and follow DNR Forest and Fish guidelines where mapping must occur on the ground. This project would provide the funding to conduct a CMZ delineation for each of these drainages and work with Clallam County Department of Community Development to incorporate those maps into the Critical Areas Ordinance.