The threshold raster includes the raw streamflow permanence probability value at a given pixel that represents the estimated critical value to differentiate between wet conditions (above the threshold) and dry conditions (below the threshold). Confidence interval rasters indicate the value above or below the threshold corresponding to the nth percentile of confidence that the pixel is wet (above) or dry (below). Raw streamflow permanence probabilities were produced by the PRObability of Streamflow PERmanence (PROSPER) model, a GIS raster-based empirical model of probabilistic predictions of a stream channel having year-round flow for any unregulated and minimally-impaired stream channel in the Pacific Northwest region, U.S. The model provides predictions of annual streamflow permanence probabilities at a 30-m spatial resolution based on monthly or annually updated values of climatic conditions and static physiographic variables associated with the upstream basin. Predictions correspond to pixels on the channel network consistent with the medium resolution National Hydrography Dataset channel network stream grid.