This USGS data release consists of 15 geospatial datasets for Smith Valley and Mason Valley, west-central Nevada, including contours representing groundwater levels based on depth-to-water measurements, groundwater-level change rasters calculated from groundwater-level contours, groundwater-level change rasters calculated from depth-to-water point values, and groundwater monitoring well locations with groundwater-level data used to develop groundwater-level contours. Groundwater-level contours representing conditions in 1970 (Huxel and Harris, 1969; Rush and Schroer, 1976) and 2006 (Lopes and Allander, 2009) were compiled from previous studies and revised with minor adjustments. Two additional groundwater-level contour datasets representing conditions in 1995 and 2020 were generated for this study. Additionally, this data release includes 2 tabular datasets of compiled surface-water diversions, USGS streamflow discharge, and calculated stream efficiency values for the East Walker, West Walker, and Walker Rivers in Smith and Mason Valleys, Nevada. Geospatial datasets include: 1) Revised groundwater-level contours for Smith Valley and Mason Valley, Nevada, 1970 2) Groundwater-level contours for Smith Valley and Mason Valley, Nevada, 1995 3) Revised groundwater-level contours for Smith Valley and Mason Valley, Nevada, 2006 4) Groundwater-level contours for Smith Valley and Mason Valley, Nevada, 2020 5) Groundwater-level change for Smith Valley and Mason Valley, Nevada, 1970-1995, approach 1 6) Groundwater-level change for Smith Valley and Mason Valley, Nevada, 1996-2006, approach 1 7) Groundwater-level change for Smith Valley and Mason Valley, Nevada, 2007-2020, approach 1 8) Groundwater-level change for Smith Valley and Mason Valley, Nevada, 1970-2020, approach 1 9) Groundwater-level change for Smith Valley and Mason Valley, Nevada, 1970-1995, approach 2 10) Groundwater-level change for Smith Valley and Mason Valley, Nevada, 1996-2006, approach 2 11) Groundwater-level change for Smith Valley and Mason Valley, Nevada, 1996-2006, approach 2 12) Groundwater-level change for Smith Valley and Mason Valley, Nevada, 2007-2020, approach 2 13) Common extent for estimating groundwater-level and groundwater storage-volume change, Smith Valley and Mason Valley, Nevada 14) Groundwater monitoring well locations and median water-level measurements used to develop groundwater-level contours for Smith Valley and Mason Valley, Nevada, 1995 15) Groundwater monitoring well locations and median water-level measurements used to develop groundwater-level contours for Smith Valley and Mason Valley, Nevada, 2020 Tabular datasets include: 16) Surface-water diversions from the East Walker, West Walker, and Walker Rivers in Smith and Mason Valleys, Nevada, 1931-2020 17) Streamflow discharge and stream efficiency for the East Walker, West Walker, and Walker Rivers in Smith and Mason Valleys, Nevada, 1948-2020