Sustainable Groundwater Management Act: groundwater adjudication.

Assembly Member Papan's groundwater management legislation establishes new requirements for courts and agencies handling groundwater basin adjudications to prevent interference with sustainability plans. The bill requires courts to ensure that judgments in comprehensive groundwater adjudications cannot authorize pumping beyond sustainable yield levels established in valid groundwater sustainability plans.

The legislation mandates that groundwater sustainability agencies review and potentially update their basin's sustainable yield determination every seven years, incorporating the best available science and information through a public review process. It also consolidates legal challenges to sustainability plans with related basin adjudications, requiring courts to address sustainable yield determinations before considering other issues.

For basins where adjudications began before 2025, the bill creates a special window until March 2026 for parties to challenge sustainability plan determinations. The amendments prohibit courts from setting safe or sustainable yield levels higher than those in validated sustainability plans unless a party proves the determination did not use best available science. The legislation maintains local agency authority to levy fees covering any new administrative costs without state reimbursement.