Wash. Rev. Code § 79.14.210
Any oil or gas lease issued under the authority of this chapter may be assigned or subleased as to all or part of the acreage included therein, subject to final approval by the department, and as to either a divided or undivided interest therein to any person. Any assignment or sublease shall take effect as of the first day of the lease month following the date of filing with the department. However, at the department's discretion, it may disapprove an assignment of a separate zone or deposit under any lease or of a part of a legal subdivision. Upon approval of any assignment or sublease, the assignee or sublessee shall be bound by the terms of the lease to the same extent as if such assignee or sublessee were the original lessee, any conditions in the assignment or sublease to the contrary notwithstanding. Any partial assignment of any lease shall segregate the assigned and retained portions thereof, and upon approval of such assignment by the department, the assignor shall be released and discharged from all obligations thereafter accruing with respect to the assigned lands.
RCW 79.14.210
Intent-2003 c 334: See note following RCW 79.02.010.