Five trace elements with human-health concerns were detected at high concentrations: arsenic, boron, molybdenum, strontium, and vanadium. Chromium and fluoride were detected at moderate concentrations.
Uranium, arsenic, and nitrate were the inorganic constituents that were most frequently detected at high concentrations, mostly in shallower wells. High and moderate concentrations of arsenic were detected in deeper wells.
This study of untreated groundwater indicates the number of samples in which inorganic or organic constituents occur in high or moderate in concentration. The study does not indicate significant problems in groundwater quality here.
Arsenic and boron were the trace elements that most frequently occurred at high concentrations. Fumigants (pesticides) were detected at high concentrations in 3% of the primary aquifers. Herbicides and insecticides were detected at low concentrations.
Vanadium and boron were detected at high and moderate concentrations in this area. High concentrations for these constituents were detected almost exclusively in samples collected in the Temecula Valley study area.