Upon notification to the department of the impairment of a groundwater right as provided in WAC 173-150-070 or on the department's own motion, the department may, when appropriate, notify the water right holders of the alleged impairment and of its intention to make investigations concerning the matter. The department may conduct aquifer or pump tests and make investigations of the withdrawal works, geology, hydrology, water quality, historic water use or other factors which may influence the local aquifers, and may make a written report of its findings. If it is determined that groundwater withdrawals by a junior water right holder or holders have caused the impairment, the department may, through regulatory orders, take one or more of the following actions:

(1) Bar or regulate the withdrawals of the junior appropriator(s) in a fashion which will preclude future impairment of the senior right;

(2) Bar or regulate the groundwater withdrawals of the most junior water right holders in order of priority of right if the aggregate withdrawals exceed the maximum amount set by the department for the area, subarea or zone pursuant to the procedures of RCW 90.44.180;

(3) Require the well owner(s), including the senior water right holder, to rehabilitate or abandon the well(s) in accordance with chapter 173-160 WAC in the case of impairment caused by the failure of wells to meet the well construction standards or the requirements of water right permit or certificate provisions, if any;

(4) Rescind authorizations for additional junior withdrawal facilities and/or reduce the authorized withdrawal rates, as appropriate, where the department finds that an appropriation by a junior right holder is the cause of the impairment and where the said junior groundwater right holder has not yet completed construction of the authorized withdrawal facilities. The department shall include a provision concerning the possibility of such rescissions as a condition on groundwater permits with multiple points of withdrawal.