The National Water-Quality Assessment (NAWQA) Program of the U.S. Geological Survey (USGS) is conducting a regional analysis of water quality in the principal aquifer systems across the United States. The Southwest Principal Aquifers (SWPA) study is build
Anning, David W. dwanning@usgs.gov,Paul, Angela P. appaul@usgs.gov,McKinney, Tim S.,et al. Predicted nitrate and arsenic concentrations in basin-fill aquifers of the Southwestern United States. 2012-01-01.