River margin and braid shapefiles digitized from aerial images of the Elwha River, Washington, 2006 to 2022

This dataset provides GIS shapefiles of river margins and braids derived from 30 aerial imagery datasets of the Elwha River, Washington spanning June 2006 through September 2022. The extent of the river’s recently active flow zone, or margins, and river braids was manually digitized in a GIS using aerial orthoimages to capture changes in the river prior to, during, and after the removal of the Glines Canyon and Elwha dams, which started in 2011 and ended in 2014. We used aerial orthoimages collected by the National Park Service, the U.S. Geological Survey, the Washington State Department of Transportation, and the National Agriculture Imaging Program, including 24 orthoimages derived from Structure-from-Motion (SfM) photogrammetry using a plane-mounted camera system designed for the Elwha River Restoration Project (Ritchie and others, 2025). Five of the image sets were collected before dam removal (2006-2011) and 25 represent conditions during and after dam removal.

To document changes associated with dam operations and dam removal, river margins and braids are provided for three separate reaches of the Elwha River: 1) the lower river, downstream of the historic Elwha Dam site, 2) the middle river, located between the former Lake Aldwell reservoir and the historic Glines Canyon dam site and 3) a control reach located upstream of the former Lake Mills reservoir, at the downstream end of Geyser Valley where there is no influence of dams or dam removal on channel evolution. In addition to the time series of channel margin and braid shapefiles, the transect locations used by East and others (2018) for GIS analyses of channel width and braiding metrics at fixed locations, spaced roughly 250 m apart, are provided as a GIS point shapefile.

References
East, A. E., Logan, J. B., Mastin, M. C., Ritchie, A. C., Bountry, J. A., Magirl, C. S., and Sankey, J. B. (2018). Geomorphic evolution of a gravel-bed river under sediment-starved versus sediment-rich conditions: River response to the world’s largest dam removal. Journal of Geophysical Research: Earth Surface, 123, 3338–3369. https://doi.org/10.1029/2018JF004703

Ritchie, A.C., Winter, B.D., and Warrick, J.A., 2025, Elwha PlaneCam – Aerial imagery and derivatives from periodic and event-response surveys of the Elwha River, Olympic Mountains, and Washington Coast, in Remote Sensing Coastal Change Simple Data Distribution Service: U.S. Geological Survey data service, accessed April 22, 2025, at https://doi.org/10.5066/P9M3NYWI