ACKNOWLEDGMENTS:
This research was supported by the U.S. Department of Energy, Office of Science, Office of Biological and Environmental Research, Environmental System Science (ESS) Program. This contribution originates from the River Corridor Scientific Focus Area (SFA) project at Pacific Northwest National Laboratory (PNNL). Pacific Northwest National Laboratory is operated by Battelle Memorial Institute for the U. S. Department of Energy under Contract DE-AC05-76RL01830.