It has a basin ground surface area of 79,724 acres (32,263 ha) and an estimated groundwater storage capacity of 960,000 acre-feet.
[3] The groundwater in the San Diego Formation is brackish, and its quality is considered to be fair to poor.
[3] Due to its proximity to the ocean, the risk of seawater intrusion is a primary concern regarding water quality.
To avoid intrusion, the Sweetwater Authority constantly monitors the basin water levels, which have remained stable since the 1980s.
The Richard A. Reynolds Groundwater Desalination Facility, in Chula Vista, was completed in 1999 and holds a production capacity of 4 million gallons of drinking water per day.
[5] Besides those of clams and other mollusks, quite a few bird fossils (which are generally rare) have been found in this geological formation.