Dumas Bay (WA50.1) is located in the southern Salish Sea, just north of Commencement Bay in Federal Way, Washington, USA. The primary species at the site are native eelgrass, Zostera marina L., and non-native eelgrass, Zostera japonica. Between 2008-2023, seagrass appeared mostly stable at the Dumas Bay SeagrassNet site with species changes occurring only in the high intertidal (+1 m, MLLW). The non-native Z. japonica increased over this timeframe in the high intertidal, while native eelgrass decreased at this elevation. However, Z. marina was stable along the lower intertidal (0 m, MLLW) and subtidal transects (-1.6 m, MLLW).