Washington State Department of Natural ResourcesThese data represent the extent of floating kelp beds ( Nereocystis luetkeana and Macrocystis pyrifera ) for each year surveyed at 22 sites in Puget Sound (2013-2025). The number of years surveyed varies by site. Polygons represent maximum bed extent, which include the kelp canopy floating on the surface and small gaps between plants (25 meter threshold for delineating discrete beds). Polygons are derived from replicate perimeter surveys from the same day in summer, between mid-July and mid-September, and represent everywhere kelp was mapped on the day. The mean bed area and standard error were calculated by averaging the area of all perimeter replicates collected on the same day. For evaluating trends in floating kelp bed area, DNR uses the mean bed area (mean_bed_area_ha), for those interested in evaluating trends, it is recommended you use the mean bed area value in the attribute table instead of calculating the area of the polygon.ArcGIS FeatureLayerhttps://hub.arcgis.com/datasets/60046622e104407ab20e5093dffcccf2_1engState of Washington Geospatial Open Data PortalPublickelp survey boundaries [Washington (State)]Web servicesWashington (State)Last Modified: 2025-11-25