1. Assistant Professor Research, Dept. of Civil and Environmental Engineering, Arizona State Univ., P.O. Box 875306, Tempe, AZ 85287.
2. Professor, Dept. of Civil and Environmental Engineering, Arizona State Univ., P.O. Box 875306, Tempe, AZ 85287.
3. Graduate Student, Dept. of Civil and Environmental Engineering, Arizona State Univ., P.O. Box 875306, Tempe, AZ 85287.
4. Director, National Science Foundation Water Quality Center and Professor, Dept. of Civil and Environmental Engineering, Arizona State Univ., P.O. Box 875306, Tempe, AZ 85287 (corresponding author).