Wat. Code, § 10720.3

(a) This part applies to all groundwater basins in the state.

(b) To the extent authorized under federal or tribal law, this part applies to an Indian tribe and to the federal government, including, but not limited to, the United States Department of Defense.

(c) The federal government or any federally recognized Indian tribe, appreciating the shared interest in assuring the sustainability of groundwater resources, may voluntarily agree to participate in the preparation or administration of a groundwater sustainability plan or groundwater management plan under this part through a joint powers authority or other agreement with local agencies in the basin. A participating tribe shall be eligible to participate fully in planning, financing, and management under this part, including eligibility for grants and technical assistance, if any exercise of regulatory authority, enforcement, or imposition and collection of fees is pursuant to the tribe’s independent authority and not pursuant to authority granted to a groundwater sustainability agency under this part.

(d) In an adjudication of rights to the use of groundwater, and in the management of a groundwater basin or subbasin by a groundwater sustainability agency or by the board, federally reserved water rights to groundwater shall be respected in full. In case of conflict between federal and state law in that adjudication or management, federal law shall prevail. The voluntary or involuntary participation of a holder of rights in that adjudication or management shall not subject that holder to state law regarding other proceedings or matters not authorized by federal law. This subdivision is declaratory of existing law.