1. Hydrogeologist, Division of Water Quality, 1636 MSC, North Carolina Dept. of Environment and Natural Resources, Raleigh, NC 27699-1636.
2. Professor, Dept. of Earth and Environmental Science, New Mexico Tech, Socorro, NM 87801 (corresponding author).
3. Graduate Student, Dept. of Civil Engineering, ECJ 8.6, Univ. of Texas-Austin, Austin, TX 78712.
4. Associate Professor, Dept. of Civil Engineering, ECJ 8.6, Univ. of Texas-Austin, Austin, TX 78712.
5. Technical Staff Member, MS J599, RRES-CH, Los Alamos National Laboratory, Los Alamos, NM 87545.