Cal. Pub. Res. Code § 5784.5

If a county board of supervisors or a city council has appointed itself as the board of directors, the board of supervisors or city council may delegate any or all of its powers to a recreation and park commission composed of five commissioners. In the case of a district governed by a board of supervisors, the commissioners may be council members of cities that are located in the district. The board of supervisors or city council shall determine whether the commissioners shall serve at its pleasure or for staggered terms of four years, subject to removal for cause. A commissioner shall be a voter of the district.