“Urban service area” means developed, undeveloped, or agricultural land, either incorporated or unincorporated, within the sphere of influence of a city, which is served by urban facilities, utilities, and services or which are proposed to be served by urban facilities, utilities, and services during the first five years of an adopted capital improvement program of the city if the city adopts that type of program for those facilities, utilities, and services. The boundary around an urban area shall be called the “urban service area boundary” and shall be developed in cooperation with a city and adopted by a commission pursuant to policies adopted by the commission in accordance with Sections 56300, 56301, and 56425.