John R. Gray is a U.S. Geological Survey (USGS) Scientist Emeritus and Principal at GraySedimentology LLC. His experiences and associated expertise in river science (hydrology, sedimentology and water quality) and limnology (nutrient cycling and water mass balance) were largely acquired during his 37 years at USGS science centers in Illinois and Arizona, and from the USGS National Center in Virginia. As the USGS Office of Surface Water’s National Sedimentologist from 1996-2014, he was responsible for technical oversight and support of a broad range of fluvial-sediment monitoring, research, and evaluation activities, and for their national and international coordination. He holds a Ph.D. in Civil Engineering from Virginia Tech; an M.S. in Hydrosystems (Civil and Environmental) Engineering from the University of Illinois; and a B.S. in Biology (aquatic ecology) from Northern Illinois University. He received the USGS Superior Service Award; Federal Interagency Subcommittee on Sedimentation’s Career Recognition Award; Department of the Interior’s Distinguished Service Award; and AIH’s Robert G. Wetzel Award for Water Quality.