(1) Any county planning under the act may reserve a portion of its twenty-year population projection for new fully contained communities, located outside of the designated urban growth areas.

(2) Proposals to authorize fully contained communities must be processed according to the locally established policies implementing the criteria set forth in RCW 36.70A.350. Approval of a new fully contained community has the effect of amending the comprehensive plan, therefore it is a legislative action and should follow the procedures associated with comprehensive plan amendments.