The U.S. Geological Survey's (USGS) SPAtially Referenced Regressions On Watershed attributes (SPARROW version 2_10) model was used to aid in the interpretation of monitoring data and simulate streamflow and water-quality conditions in streams across the Pacific Region of the Unites States. SPARROW is a hybrid empirical/process-based mass balance model that can be used to estimate the major sources and environmental factors that affect the long-term supply, transport, and fate of contaminants in streams. The spatially explicit model structure is defined by a river reach network coupled with contributing catchments. The model is calibrated by statistically relating watershed sources and transport-related properties to monitoring-based water-quality load estimates. This USGS data release includes input and output files associated with 2012 SPARROW simulations of streamflow, total nitrogen, total phosphorus and suspended sediment load in streams of the Pacific region. Model construction, calibration and results are described in Wise (2019, https://doi.org/10.3133/sir20195112). First posted - January 6, 2020(available from author) Revised - June 08, 2020