1. Graduate Student, Dept. of Earth Science, Univ. of California, Santa Barbara, CA 93106; and Staff Scientist, Kear Groundwater, P.O. Box 2601, Santa Barbara, CA 93120.
2. Professor, Dept. of Earth Science, Univ. of California, Santa Barbara, CA 93106 (corresponding author).
3. Chief Hydrogeologist, Water Replenishment District of Southern California, 4040 Paramount Blvd., Lakewood, CA 90712.