June 7, 2016--USGS map reveals long-term changes in America’s groundwater quality (Circle of Blue)

Chloride and nitrate concentrations are rising and arsenic levels are holding steady or falling. Those are two of the conclusions from a U.S. Geological Survey assessment of changes in the nation’s groundwater quality in the last two decades. The federal science agency published the results on Thursday in an interactive online map. The contaminants in the assessment are a roster of two dozen undesirable intruders that can cause health and environmental damage if not cleansed before consumption: cancer-causing chemicals, radioactive elements, and nutrients that foul the Great Lakes and Gulf of Mexico with algae. More than 140 million people in the United States use groundwater as their primary source of drinking water. Of that group, some 45 million people use private wells, which are not subjected to the same legally enforceable quality standards as water utilities and therefore more vulnerable to contamination. The groundwater quality map shows whether concentrations of pesticides, nutrients, heavy metals, gasoline additives, and other chemicals are rising or falling. For some contaminants, such as chloride and nitrate, there is a clear upward trend nationally. Other chemicals show regional trends. Uranium, for one, is rising in California’s Central Valley and in the Southwest but not elsewhere. Still other chemicals, like toluene, a gasoline additive, show no detectable increase or decrease. The study is part of the USGS’s National Water Quality Assessment, whose purpose is to identify long-term changes in the quality of rivers and aquifers. To view the full article visit the Circle of Blue.