1. Nitrate in ground water : using a model to simulate the probability of nitrate contamination of shallow ground water in the conterminous United States Author/Creator: Hitt, Kerie J. Publication/Creation: Reston, Va. : USGS National Water-Quality Assessment Program, 2005 Format: Map Access & Availability: Loading
2. Nitrogen, sulfate, chloride, and manganese in ground water in the alluvial deposits of the South Platte River Valley near Greeley, Weld County, Colorado Author/Creator: Geological Survey (U.S.), cartographer Publication/Creation: Denver, Colorado : Open-File Services Section, Western Distribution Branch, U.S. Geological Survey Format: Map Access & Availability: Loading