(1) Each county or city comprehensive plan must be coordinated with, and consistent with, the comprehensive plans of other counties and cities that share common borders or related regional issues with that county or city. Determining consistency in this interjurisdictional context is complicated by the differences in timing of comprehensive plan adoption and subsequent amendments.

(2) Initially, interjurisdictional consistency should be met by the adoption of comprehensive plans, and subsequent amendments, which are consistent with and carry out the relevant countywide planning policies and, where applicable, the relevant multicounty planning policies. Adopted countywide planning policies are designed to ensure that county and city comprehensive plans are consistent. More detailed recommendations about countywide planning policies are contained in WAC 365-196-305.

(3) To better ensure consistency of comprehensive plans, counties and cities should consider using similar policies and assumptions that apply to common areas or issues.

(4) Counties and cities should use consistent population projections and planning horizons when completing the periodic review and evaluation of comprehensive plans and development regulations. The planning horizon should start on the relevant deadline specified in RCW 36.70A.130(5) and encompass a minimum of 20 years.