Results of nitrate sampling in the Torrington, Wyoming, Wellhead Protection Area, 1994-98

A monitoring program for nitrate in ground water in and near Torrington, Wyoming was conducted by the Town of Torrington from April 1994 through March 1997, and cooperatively by the Town of Torrington and the U.S. Geological Survey from May 1997 through August 1998. Trends in nitrate concentrations were determined for the period of time covered by both monitoring programs. A significant trend was detected at 34 of the 72 sites. Twenty-six sites had nitrate concentrations that were increasing, and eight sites had nitrate concentrations that were decreasing. Nitrogen isotope data were also collected at selected sites. These data indicate that the source of nitrate in ground water in and around Torrington is probably not from human or animal waste, but rather organic soil nitrogen, or ammonium or nitrate fertilizer.