A new report from the USGS Southwest Principal Aquifers (SWPA) study looks at the factors that affect water quality in basin-fill aquifers in the Southwestern United States including the Basin and Range basin-fill aquifers in California, Nevada, Utah, and Arizona.
"Four relatively common contaminants (dissolved solids, nitrate, arsenic, and uranium) and two contaminant classes (volatile organic compounds (VOCs) and pesticide compounds) were investigated for sources and controls affecting their occurrence and distribution above specified levels of concern in groundwater of the case-study basins."
Ref: Bexfield, L.M., Thiros, S.A., Anning, D.W., Huntington, J.M., and McKinney, T.S., 2011, Effects of natural and human factors on groundwater quality of basin-fill aquifers in the southwestern United States—conceptual models for selected contaminants: U.S. Geological Survey Scientific Investigations Report 2011-5020, 90 p.