Acting under the authority as hereinbefore set forth and RCW 79.01.096, the board of natural resources declares it to be the policy of the department of natural resources to grant priority to public school districts in the leasing of common school lands under the jurisdiction of the department of natural resources: Provided, however, That the needs of such lands for public school purposes is clearly demonstrated and the request is not in excess of actual or reasonably foreseeable needs.