This repository contains data from sediment cores collected during 2017-2018 from 17 impoundments that are located on tributaries to the tidal portion of the Hudson River as part of a larger NERRs collaborative project entitled Dams and Sediment on the Hudson (DaSH). A companion dataset that contains sediment core data from Hudson tidal marshes is archived at UMass Scholarworks data repository. Sediment cores collected from impoundments behind dams were recovered via piston push coring, which tends to minimize compaction and be representative of true sediment thicknesses. The general workflow for cores included (1) splitting; (2) Itrax XRF scanning; (3) subsampling cores ~10 cm spacing; (4) drying and burning samples for percent water, organic, and mineral (Dean, 1974). Combusted samples were gently disaggregated with mortar and pestle and analyzed for grain size on a Coulter Laser Particle Size Analyzer. Basal sediments were identified by low organic content and a contrast in grainsize or sediment texture with overlying pond sediment. Sediment age was constrained by the construction date of the corresponding dam, when that information was available, and by 137Cs chronology when absent. The small sediment masses present in most of these dams relative to expected masses based on regional sediment yield is representative of the small aggregate trapping of sediment by legacy mill dams in the Northeast US, highlighted in the manuscript “Watershed sediment supply and potential impacts of dam removals for an estuary,” submitted to Estuaries and Coasts in March, 2020.