Following the most extensive study of nutrients in the nation's water resources, the U.S. Geological Survey finds that the drinking water standard for nitrate, a nutrient commonly derived from fertilizer, was exceeded in 21% of shallow wells in agricultural areas. The standard was exceeded in only 1% of public supply wells and in very few streams.
The study indicates that nitrate levels in ground and surface waters are higher in agricultural areas, indicating patterns of contamination related to land use. The highest concentrations of nitrate were in shallow ground water, less than 100 feet below the surface. Concentrations were higher in parts of the Northeast, Midwest, and on the West Coast, with generally lower concentrations in the Southeast.