This digital data set defines the altitudes of the tops of 16 model layers simulated in the Death Valley regional ground-water flow system (DVRFS) transient flow model. The area simulated by the DVRFS transient ground-water flow model is an approximately 45,000 square-kilometer region of southern Nevada and California. The thickness of model layers is derived by sequentially subtracting the altitudes of the uppermost to the lowermost model layers. Most model layers range in thickness from 50 to more than 300 meters, and thickness generally increases with depth (Faunt and others, 2004). The upper model layers are used to simulate relatively shallow flow primarily through basin-fill sediments and volcanic rocks and adjacent mountain ranges. The lower layers predominantly simulate deep flow through a regional carbonate-rock aquifer beneath the basin fill and mountain ranges in the DVRFS. The DVRFS transient ground-water flow model is one of the most recent in a number of regional-scale models developed by the U.S. Geological Survey (USGS) for the U.S. Department of Energy (DOE) to support investigations at the Nevada Test Site (NTS) and at Yucca Mountain, Nevada (see "Larger Work Citation", Chapter A, page 8).