If the department determines that a proposed appropriation of groundwater would cause a lowering of the water levels below a reasonable or feasible pumping lift in any withdrawal facilities of an existing groundwater right holder or that approval of the proposed appropriation would impair any existing water rights or would otherwise be detrimental to the public welfare, the application shall be rejected. If, however, the application is to be rejected because of conflict with existing rights, and the applicant thereafter indicates that such existing rights will be acquired by the applicant by purchase, gift or condemnation under RCW 90.03.040, the department may issue an interim conditional ruling and defer final decision on the application for a reasonable period of time to be specified by the department in the interim ruling.