A vertical profile of downwelling spectral irradiance at different depths within the water column was measured on the Snake River in Grand Teton National Park, WY, August 23, 2015, to support research on remote sensing of rivers. Downwelling spectral irradiance data were collected using an Analytical Spectral Devices FieldSpec3 spectroradiometer operated in irradiance mode and deployed from a customized measurement crane. The measurements were made in a reach downstream of Jackson Lake referred to as Swallow bend. In addition, the depth at which each downwelling spectral irradiance measurement was made was obtained using an Onset Hobo pressure transducer mounted next to the spectroradiometer foreoptic on the crane. This data release provides both the downwelling irradiance spectra and the depths at which these measurements were made and can be used to characterize attenuation of light within the water column. This information can facilitate efforts to map river bathymetry from field spectra or passive optical remotely sensed data.