In June 1995, the Columbia River Estuary Study Taskforce (CREST) obtained 295 true color aerial photographs (1:12,000) of Willapa Bay, Washington, from the Washington State Department of Transportation (WDOT). These photographs were suitable for interpreting submerged, rooted aquatic vascular plant populations.

Field surveys were conducted in August 1995 by personnel from Oregon State University, the Columbia River Estuary Study Taskforce, and the Washington Department of Natural Resources. These surveys aimed at spectral signature development, verification, and habitat observation. The submerged plant populations were subsequently interpreted and mapped from the photographs and then transferred onto 1:12,000 orthophoto maps provided by the state of Washington. This information was digitized into a geographic information system to create a habitat map. The entire process, including interpretation, digitization, and photography acquisition, adhered to the rigorous parameters detailed in the Coastal Change Analysis Program protocol.

Two supplementary datasets enhanced the interpreted habitat polygons. In 1996, WDOT provided color aerial videography for post-mapping verification and accuracy assessments. Additionally, the University of Washington collected videography from 29 underwater transects to specifically verify the deep-water edge of selected seagrass beds in the bay's southern portion. This videography included direct recording on the tape of date, time, geographic coordinates, and depth, updated every 2 to 4 seconds, with latitude and longitude provided by a differentially corrected global positioning system.

The initial presence or absence map created by the taskforce was later segmented by depth to distinguish between two different seagrass communities and facilitate field accuracy assessment. Final field verification of the data was carried out in the summer of 1997 by CREST and NOAA Office for Coastal Management staff. The resulting benthic data is classified according to the System for Classification of Habitats in Estuarine and Marine Environments.

This project aimed to establish national baseline data on benthic habitats and provide local resource managers with seagrass distribution information. A key focus was the distribution of Zostera japonica on intertidal mudflats and the threat posed by the expansion of Spartina alterniflora to the robust local oyster fishery. Healthy seagrass beds are vital, supporting endangered migratory waterfowl like the black brant, as well as commercially and recreationally valuable salmon.

The layers available within the data download include biotic, geoform, and substrate.

Partners: Columbia River Estuary Study Taskforce, Oregon State University, and the Washington State Department of Natural Resources