Understanding the age of groundwater, and hence travel times, in the Southern Great Basin is of importance because of possible radionuclide migration from the Nevada Test Site, and the rapidly expanding population of Las Vegas. This study uses two independent methods of radiocarbon dating to determine the travel times of several groundwater flow paths in the Southern Great Basin. The first method involves using paleoclimatic data from Devils Hole to avoid the difficulties inherent in radiocarbon dating with dissolved inorganic carbon in carbonate aquifers. The second method uses new techniques developed to date groundwater with the carbon isotopes of dissolved organic carbon (DOC). The DOC method in particular has the potential for application in many different hydrogeologic settings.