1. Assistant Professor, Dept. of Biological Systems Engineering, Auburn Univ., 203 Corley Building, Auburn, AL 36849-5417 (corresponding author).
2. Associate Professor, Dept. of Civil and Environmental Engineering, Virginia Tech, 308 Patton Hall, Blacksburg, VA 24061.
3. Director, Occoquan Watershed Laboratory, 9408 Prince William St., Manassas, VA 20110-5670.
4. Associate Director, Occoquan Watershed Laboratory, 9408 Prince William St., Manassas, VA 20110-5670.
5. Associate Professor, Dept. of Crop and Soil Environmental Sciences, Virginia Tech, 363 Smyth Hall, Blacksburg, VA 24061.