Mapping pollutant source to enhance water quality conservation in agricultural watersheds: Nonpoint no more?

David E. James is retired from the USDA Agricultural Research Service (ARS), Ames, Iowa. Mark D. Tomer is retired from the USDA ARS, Tauranga, New Zealand. Sarah A. Porter is a geographer at the USDA ARS, St. Paul, Minnesota. Richard M. Cruse is a professor at Iowa State University, Ames, Iowa. Emily Zimmerman is the Wisconsin Director of Agricultural Strategies at The Nature Conservancy, Madison, Wisconsin.