This digital data set defines the boundary of the steady-state ground-water flow model built by IT Corporation (1996). The regional, 20-layer ground-water flow model was developed for the Underground Test Area (UGTA) Phase I project to simulate the Nevada Test Site and surrounding areas. The model was used for estimating the amount of water moving through the ground-water system, predicting the movement of contaminants, evaluating uncertainty in these predictions, and supplying boundary conditions for more detailed models of the underground testing areas. The U.S. Geological Survey integrated the IT Corporation (1996) model with the ground-water flow model by D'Agnese and others (1997) to develop a transient flow model of the Death Valley regional ground-water flow system (DVRFS) for the Department of Energy in 2004 (see "Larger Work Citation", Chapter A, pages 7-9, for details). Reference: D'Agnese, F.A., Faunt, C.C., Turner, A.K., and Hill, M.C., 1997, Hydrogeologic evaluation and numerical simulation of the Death Valley regional ground-water flow system, Nevada and California: U.S. Geological Survey Water-Resources Investigations Report 96-4300, 124 p. http://pubs.er.usgs.gov/pubs/wri/wri964300