Elemental compositions are reported for the fine fraction of surface sediments from Bellingham Bay (June 2017 and March 2019) and in the fine fraction of streambank sediment from the Nooksack River (September 2017, March 2019, September 2019), Squalicum Creek (March and September 2019), Whatcom Creek (March and September 2019), and Padden Creek (March and September 2019). Major oxide percentages are reported in Nooksack River fine sediment collected in September 2017. Ancillary data for sediment collected during 2017 and 2019 from Bellingham Bay, Nooksack River, and small creeks include: percent weights of gravel, sand, and fines; total organic carbon content (TOC); carbonate content (CaCO3); ratios of stable carbon 13/12 (d13C) and nitrogen 15/14 (d15N) isotopes and total carbon to total nitrogen (C:N); and short-lived cosmogenic radionuclide activities (Beryllium-7, Cesium-137, and excess Lead-210).