Landowners in California are entitled to pump and use a reasonable amount of groundwater from a basin underlying their land to put it to a beneficial, non-wasteful use. When there is insufficient water to meet the demands of landowners, they are expected to reduce their use to bring extractions into the “safe yield” of the basin to prevent overdraft. Safe yield is the rate at which groundwater can be withdrawn without causing long-term decline of water levels or other undesirable effects such as subsidence.
The SGMA is designed to address issues related to both overdraft and safe yield, but does not change existing groundwater rights. Specifically, Water Code section 10720.5(b) says that nothing in the legislation “determines or alters surface water rights or groundwater rights under common law or any provisions of law that determines or grants surface water rights.”