1. U.S. Environmental Protection Agency, National Exposure Research Laboratory, 26 W. Martin Luther King Dr, Cincinnati, OH 45268, U.S.A.
2. U.S. Environmental Protection Agency, Region 9, Water Division (WTR‐2), 75 Hawthorne Street, San Francisco, CA 94105, U.S.A.
3. U.S. Environmental Protection Agency, Region 9 Laboratory (PMD‐2), 1337 S 46th Street, Richmond, CA 94804, U.S.A.
4. Department of Fisheries and Wildlife, Oregon State University, Corvallis, OR 97333, U.S.A.
5. California Department of Fish and Game, Bay‐Delta Unit, 4001 N. Wilson Way, Stockton, CA 95205, U.S.A.