This digital map database represents the general distribution of the geology (bedrock and surficial deposits) in San Mateo County. Accompanying text file (*.txt or *.ps) provides current information on the geologic structure and stratigraphy.
The constituent present at high concentrations in the greatest proportion of the primary aquifer system was TDS, which is an indicator of salinity. Perchlorate was also present at moderate concentration in 42% of samples.
Using ground-water geochemical analyses, and mathematical models, the factors affecting the quality of public water supply were identified as pumping schedule, screened interval, past land use within the recharge area, and natural geochemical conditions.
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.
What causes changes in the hydrology, the ecology and the water quality of the Sacramento-San Joaquin River Delta and the San Francisco Bay estuary? These studies help state and local agencies manage resources well.
This report presents geochemical data generated during mineral and environmental assessments for the Bureau of Land Management in northern Nevada, northeastern California, southeastern Oregon, and southwestern Idaho, along with metadata and maps.
After the powerful earthquake of April 18, 1906, staff of the U.S. Geological Survey stationed in Sacramento and Berkeley brought help to the residents of devastated San Francisco, documented the effects of the quake, and investigated its causes.
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.
Recent study indicating inorganic constituents as the primary items of concern in this area. Chemical and mineralogical compositions of the aquifer rocks probably explain variation among localities here.