Streets and Highways Code § 36620.5

36620.5.

A county may not form a district within the territorial jurisdiction of a city without the consent of the city council of that city. A city may not form a district within the unincorporated territory of a county without the consent of the board of supervisors of that county. A city may not form a district within the territorial jurisdiction of another city without the consent of the city council of the other city.