- Nitrate loads and concentrations in surface-water base flow and shallow groundwater for selected basins in the United States, water years 1990-2006, by Norman E. Spahr ... [and others]
- County-level estimates of nitrogen and phosphorus from commercial fertilizer for the conterminous United States, 1987-2006, by Jo Ann M. Gronberg and Norman E. Spahr
- Water-quality, streamflow, and ancillary data for nutrients in streams and rivers across the nation, 1992-2001, David K. Mueller and Norman E. Spahr
- Nutrients in streams and rivers across the nation -- 1992-2001, by David K. Mueller and Norman E. Spahr
- Low-flow water-quality characterization of the Gore Creek watershed, upper Colorado River basin, Colorado, August 1996, Kirby H. Wynn and Norman E. Spahr
- Water quality in the Upper Colorado River Basin, Colorado, 1996-98, by Norman E. Spahr ... [et al.]
- Development and application of regression models for estimating nutrient concentrations in streams of the conterminous United States, 1992-2001, by Norman E. Spahr, David K. Mueller, David M. Wolock, Kerie J. Hitt, and JoAnn M. Gronberg