Comparison of chlorofluorocarbon age-dating with particle-tracking results of a regional ground-water flow model of the Portland Basin, Oregon and Washington / Comparison of chlorofluorocarbon age dating with particle-tracking results of a regional ground-water flow model of the Portland Basin, Oregon and Washington Hinkle, Stephen R. Snyder, Daniel T. Intergovernmental Resource Center of Clark County (Wash.) Geological Survey (U.S.) Groundwater flow Groundwater tracers Chlorofluorocarbons 551 FOR 1997 A059 Or. Shipping list no.: 97-0374-P. Denver, Colo. : U.S. Dept. of the Interior, U.S. Geological Survey : For sale by Branch of Information Services [distributor], [1997] [1997] Text v, 47 p. : U.S. Geological Survey water-supply paper ;