(a) The state, an agency or a political subdivision of the state, an agency of the United States, or a person may apply to the commissioner to reserve sufficient water to maintain a specified instream flow or level of water at a specified point on a stream or body of water, or in a specified part of a stream, throughout a year or for specified times, for
(1) protection of fish and wildlife habitat, migration, and propagation;
(2) recreation and park purposes;
(3) navigation and transportation purposes; and
(4) sanitary and water quality purposes.
(b) Upon receiving an application for a reservation under this section, the commissioner shall proceed in accordance with AS 46.15.133.
(c) The commissioner shall issue a certificate reserving the water applied for under this section if the commissioner finds that
(1) the rights of prior appropriators will not be affected by the reservation;
(2) the applicant has demonstrated that a need exists for the reservation;
(3) there is unappropriated water in the stream or body of water sufficient for the reservation; and
(4) the proposed reservation is in the public interest.
(d) After the issuance of a certificate reserving water, the water specified in the certificate shall be withdrawn from appropriation and the commissioner shall reject an application for a permit to appropriate the reserved water.
(e) A reservation under this section does not affect rights in existence on the date the certificate reserving water is issued.
(f) At least once each 10 years the commissioner shall review each reservation under this section to determine whether the purpose described in (a) of this section for which the certificate reserving water was issued and the findings described in (c) of this section still apply to the reservation. If the commissioner determines that the purpose, or part or all of the findings, no longer apply to the reservation, the commissioner may revoke or modify the certificate reserving the water after notice, hearing when appropriate, and a written determination that the revocation or modification is in the best interests of the state.