This study models subsurface salinity in the vicinity of Fruitvale and Rosedale Ranch oil fields.

Some key findings:

• Thickness and depth of fresh and brackish groundwater varies across these oil fields.
• Salinities vary within the Chanac formation from 5,000 to about 30,000 ppm TDS.
• This variation is systematic.
• Variation is caused by (1) clay layer thickness, (2) distance from a major freshwater recharge source, and (3) faults.