(1) Consistent with the provisions of chapter 90.54 RCW, it is the policy of the department to preserve an appropriate minimum instream flow in all perennial streams and rivers of the Okanogan River Basin for protection of instream values.

(2) In keeping with this policy, a partial year closure from May 1 to October 1 will be established on all perennial streams in the basin except those with established minimum instream flows as described in WAC 173-549-020.

(3) The upper Okanogan stream management unit as established in WAC 173-549-020(1) is closed to further consumptive appropriation from June 15 through August 31 with the exception of single-domestic use and stockwatering use, provided that no alternative source of supply is available.

(4) When a project (as described in WAC 173-549-020(5)) is proposed on a stream that is closed to further appropriations, the department shall deny the water right application unless the project proponent can adequately demonstrate that the project does not conflict with the intent of the closure.