California Code, Water Code - WAT § 1027

(a) Any water lease agreement entered into pursuant to this chapter involving the transfer of water from the Sacramento-San Joaquin Delta shall provide outflow consistent with the carriage water requirements determined by the department to be necessary for the transfer of the water subject to the lease to maintain the water quality which would exist in the delta without the transfer undertaken in connection with the water lease.

(b) Any water lease agreement providing for the lease of water from a lessor north of the Sacramento/San Joaquin Delta to a lessee south of the Sacramento/San Joaquin Delta shall provide for an amount of water for delta salt water repulsion and environmental purposes as administratively prescribed by the state board in proportion to all similar requirements for delta exports.