(1)(a) The county legislative authority may direct the county planning commission to set open space priorities and adopt, after a public hearing, an open space plan and public benefit rating system for the county. The plan shall consist of criteria for determining eligibility of lands, the process for establishing a public benefit rating system, and an assessed valuation schedule. The assessed valuation schedule shall be developed by the county assessor and shall be a percentage of market value based upon the public benefit rating system. The open space plan, the public benefit rating system, and the assessed valuations schedule shall not be effective until approved by the county legislative authority after at least one public hearing: PROVIDED, That any county which has complied with the procedural requisites of chapter 393, Laws of 1985, prior to July 28, 1985, need not repeat those procedures in order to adopt an open space plan pursuant to chapter 393, Laws of 1985.
(b) County legislative authorities, in open space plans, public benefit rating systems, and assessed valuation schedules, shall give priority consideration to lands used for buffers that are planted with or primarily contain native vegetation.
(c) "Priority consideration" as used in this section may include, but is not limited to, establishing classification eligibility and maintenance criteria for buffers meeting the requirements of (b) of this subsection.
(d) County legislative authorities shall meet the requirements of (b) of this subsection no later than July 1, 2006, unless buffers already receive priority consideration in the existing open space plans, public benefit rating systems, and assessed valuation schedules.
(2) In adopting an open space plan, recognized sources shall be used unless the county does its own survey of important open space priorities or features, or both. Recognized sources include but are not limited to the natural heritage database; the state office of historic preservation; the recreation and conservation office inventory of dry accretion beach and shoreline features; state, national, county, or city registers of historic places; the shoreline master program; or studies by the parks and recreation commission and by the departments of fish and wildlife and natural resources. Features and sites may be verified by an outside expert in the field and approved by the appropriate state or local agency to be sent to the county legislative authority for final approval as open space.
(3) When the county open space plan is adopted, owners of open space lands then classified under this chapter shall be notified in the same manner as is provided in RCW
84.40.045 of their new assessed value. These lands may be removed from classification, upon request of owner, without penalty within thirty days of notification of value.
(4) The open space plan and public benefit rating system under this section may be adopted for taxes payable in 1986 and thereafter.