Eelgrass (Zostera marina) characteristics, sediment grain size distributions, sediment total organic carbon contents (TOC), carbon isotope ratios of sediment organic matter, and total carbon to total nitrogen ratios were measured at four lower intertidal sites in Bellingham Bay, Washington, July 2-5, 2019.

Sediment grain-size distributions and total organic carbon contents were measured at four intertidal sites and three subtidal sites along the urban waterfront (east shore) of Bellingham Bay, Washington, July 3-11, 2019 and June 6-August 31, 2020. Intertidal substrate was sampled in eelgrass beds, and subtidal substrate was sampled inside and outside of the deep edge of eelgrass beds.