Wash. Admin. Code § 392-135-015
Any school district may cooperate with one or more other school districts in the joint maintenance and operation of educational programs or services:
[Statutory Authority: RCW 28A.150.290 and 84.52.0531. WSR 13-12-004, § 392-135-015, filed 5/22/13, effective 6/22/13; Order 7-75, § 392-135-015, filed 12/22/75. Formerly WAC 392-15-910, 392-15-735.]