Arsenic and nitrate are the constituents found most commonly at high concentrations in the primary aquifers. Arsenic comes from natural sources and is affected by pH and dissolved oxygen.
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.
Process and plan to be used to provide reliable evaluations of the potential effects of groundwater production and help guide sustainable management of the resource.
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.
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.
Organic solvents are the chief concern in this area, which has given rise to a systematic program of monitoring and water treatment. This study shows relatively recent results.
Recent study encountered occasional high values of radioactive trace elements, but the water quality in this area as monitored compares favorably to more urban areas studied by the same group.
The groundwater component of streamflow is important because it is indicative of the sustained flow of a stream during dry periods, is often of better quality, and has a smaller range of temperatures, than surface contributions to streamflow.
Shallow groundwater has good quality, but salinity measured in wells suggests the thin lens of freshwater under the coastal plain will be vulnerable to saltwater intrusion as a consequence of pumping.