This digital data set defines the subregions of the transient ground-water flow model of the Death Valley regional ground-water flow system (DVRFS). Subregions are used to more readily describe and evaluate the source, occurrence, and movement of ground water within and between the smaller areas of the DVRFS, which is an approximately 45,000 square-kilometer region of southern Nevada and California. The subregions, first described by D'Agnese and others (1997), consist of a northern, central, and southern subregion. The subregions are defined by grouping ground-water sections into ground-water basins and ultimately grouping ground-water basins into ground-water subregions. Where applicable, ground-water flow paths were used to modify the section boundaries so that the basin and subregion boundaries do not always coincide with the section boundaries. The subregions, basins, and sections are used for descriptive purposes only and do not define independent flow systems. The subregions, basins, and sections are delineated primarily on (1) location of recharge areas; (2) regional hydraulic gradients; (3) distribution of aquifers, structures, and confining units that affect flow; (4) location of major discharge areas; and (5) hydrochemical composition of the ground water.