California Code, Streets and Highways Code - SHC § 25345

The resolution shall specifically set forth the sum of money levied upon each county within the district and shall briefly recite the facts requiring the levy.  After the adoption of the resolution a certified copy of the same shall be forthwith transmitted to the clerks of the several boards of supervisors of the counties composing the district.  The counties shall then be obligated to pay the amount of the levy unless other provisions for financing are made.