Lower precipitation and recharge, with deeper groundwater levels, suggest this basin will be less susceptible to contamination than others nearby, but may be susceptible to saltwater intrusion brought on by well pumping.
Trace elements were present at high concentrations in 32% of the primary aquifers here, and at moderate concentrations in 17%. Of particular interest are aluminum, arsenic, vanadium, boron, fluoride, chromium, lead, and molybdenum.
The occurrence of solvents in the groundwater is not correlated with current overlying land use and human activities. Rather, the solvents are from legacy industrial uses, and it has taken decades for the groundwater to move to where it is now pumped.
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.