California's future depends on protecting groundwater quality. Having groundwater with very poor quality is like having no groundwater at all.
Some groundwater basins bordering the San Francisco Bay and the Delta have experienced saline water intrusion due to over-extraction of groundwater. In a few places in the Sacramento Valley, shallow salt water makes the groundwater unusable. In other areas, elevated levels of naturally occurring boron restrict the type of crops that can be irrigated with groundwater. In some areas, nitrates and other introduced chemicals make the groundwater unfit for domestic use.