Atmospheric particulate matter deposited to snow cover diminishes snow-surface albedo and results in early onset and rapid snow melting, challenging management of downstream water resources. We present here physical and chemical data from snow samples from 14 sites during the melt seasons of water years 2013-16 across 60,000 km2 of the central Rocky Mountains within the Upper Colorado River basin. The samples represented the last remaining particulate-laden surfaces after individual dust layers and particles from background fallout had merged. The samples were examined for relations among properties of spectral reflectance, types and amounts of light absorbing particles (LAPs), chemical composition, and particle sizes.