(1) Based on historical and current low flows and water withdrawals by existing water right holders, the department has determined that no waters are available for new consumptive uses during periods of low surface water flows. Therefore, all rivers and streams in the basin are seasonally closed to any further consumptive appropriation from May 1 to November 30 with the exception that the Walla Walla River and all of its tributaries between Stateline and Detour Road at MP 5a, and Mill Creek and all of its tributaries from the confluence with the Walla Walla to the headwaters shall be closed from June 1 to November 30.

(2) Based on the hydrogeology of the basin, the department finds that gravel aquifers in the basin are hydraulically connected to surface waters in the basin. Therefore, the gravel aquifers are closed. Exception to this closure is provided for future permit-exempt groundwater withdrawals as prescribed in WAC 173-532-050 and for nonconsumptive groundwater use as prescribed in WAC 173-532-045. The closure does not affect the construction of a replacement well or new additional well or wells consistent with the conditions set in RCW 90.44.100.

(3) Future permits to withdraw surface water during nonclosure periods, shall be limited to environmental enhancement projects as described in WAC 173-532-055.

(4) All unappropriated surface waters and groundwater from the gravel aquifer for which an exception to the closure does not apply, are hereby appropriated during the above periods of closure for purposes of protecting and preserving fish and wildlife and other instream values.