The U.S. Geological Survey
United States Virgin Islands
Stephen Kalkhoff is currently the supervisor of the Water Quality and Environmental Health Unit of the U.S. Geological Survey Iowa Water Science Center. Since 1994, he has been the chief of the Eastern Iowa Basins(EIWA) study unit of the USGS National Water-Quality Assessment program. Responsibilities have included planning to incorporate both National and local program objectives, collection of water quality data, and interpretation of the results. He is currently evaluating the trends in nutrients and pesticide concentrations and transport during the last decade in Iowa’s major rivers. Kalkhoff also is documenting the concentrations and transport of nitrogen and phosphorus in the Missouri River basin during floods in 2011.
groundwater quality water cycle surface water quality land use and land cover nonpoint-source pollution
Kalkhoff, S.J., 2013, Occurrence and transport of nutrients in the Missouri River Basin, April through September 2011: U.S. Geological Professional Paper 1798–G, 23 p
Green, C. T., B. A. Bekins, S. J. Kalkhoff, R. M. Hirsch, L. Liao, and K. K. Barnes (2014), Decadal surface water quality trends under variable climate, land use, and hydrogeochemical setting in Iowa, USA, Water Resources. Research., vol. 50, issue 3, pp. 2425-2443
Kalkhoff, S.J., Hubbard, L.E., Tomer, M.D., and James, D.E., 2016, Effect of variable annual precipitation and nutrient input on nitrogen and phosphorus transport from two Midwestern agricultural watersheds, Science of the Total Environment, vol. 559, pp. 53-62,