(1) A code city as provided in subsection (2) of this section may annex unincorporated territory pursuant to an interlocal agreement. This method of annexation shall be an alternative method and is additional to all other methods provided for in this chapter.

(2) The county legislative authority of a county and the governing body of a code city may jointly initiate an annexation process for unincorporated territory by adopting an interlocal agreement as provided in chapter 39.34 RCW and under this section between the county and code city within the county. If a code city is proposing to annex territory where the sole access or majority of egress and ingress for the territory proposed for annexation is served by the transportation network of an adjacent city, or that will include areas in a fire protection district under Title 52 RCW, regional fire protection service authority under chapter 52.26 RCW, water-sewer district under Title 57 RCW, or transportation benefit district under chapter 36.73 RCW, the code city must provide written notice to the governing authority of such adjacent city, regional fire protection service authority, fire protection district, water-sewer district, or transportation benefit district. Such adjacent city or notified district shall have thirty calendar days from the date of the notice to provide written notice of its interest in being a party to the interlocal agreement. If timely notice is provided, such city or district shall be included as a party to the interlocal agreement. If the adjacent city or district does not approve the interlocal agreement, the annexation may not proceed under this section. For purposes of this subsection, "adjacent" means that the territory proposed for annexation is contiguous with the existing city limits of the nonannexing city. The interlocal agreement must ensure that for a period of five years after the annexation any parcel zoned for residential development within the annexed area shall:

(a) Maintain a zoning designation that provides for residential development; and

(b) Not have its minimum gross residential density reduced below the density allowed for by the zoning designation for that parcel prior to annexation.

(3) The county and code city shall jointly agree on the boundaries of the annexation and its effective date. The interlocal agreement shall describe the boundaries of the territory to be annexed and set a date for a public hearing on such agreement for annexation. An interlocal agreement may include phased annexation of territory, and may be amended following the same process as initial approval, including adding additional territory. A public hearing shall be held by each legislative body, separately or jointly, before the agreement is executed. Each legislative body holding a public hearing shall:

(a) Separately or jointly, publish a notice of availability of the agreement at least once a week for four weeks before the date of the hearing in one or more newspapers of general circulation within the code city and one or more newspapers of general circulation within the territory proposed for annexation; and

(b) If the legislative body has the ability to do so, post the notice of availability of the agreement on its website for the same four weeks that the notice is published in the newspapers under (a) of this subsection. The notice shall describe where the public may review the agreement and the territory to be annexed.

(4) On the date set for hearing, the public shall be afforded an opportunity to be heard. Following the hearing, if the legislative body determines to effect the annexation, they shall do so by ordinance. If the annexation agreement includes phased annexation of territory, the legislative body shall adopt a separate ordinance at the time of each phase of annexation. Upon the date fixed in the ordinance of annexation the area annexed shall become part of the city. If the annexation ordinance provides for assumption of indebtedness or adoption of a proposed zoning regulation, the notice shall include a statement of such requirements. Upon passage of the annexation ordinance a certified copy shall be filed with the board of county commissioners of the county in which the annexed property is located.

Finding—2020 c 142: "The legislature finds that city annexations of unincorporated areas within urban growth areas will be more efficient and effective if the county and city develop a jointly approved interlocal agreement so as not to create illogical boundaries or islands of unincorporated territory." [ 2020 c 142 s 1.]