Cal. Educ. Code § 41981

For purposes of this chapter, and notwithstanding the provisions of Section 6505.5 of the Government Code, the fiscal officer of the joint powers entity shall be the county superintendent of schools. If the joint powers entity is situated partly within two or more counties, in terms of its participating school districts, the fiscal officer shall be the county superintendent of schools of the county in which the greatest area of the joint powers entity lies.