Cal. Public Utilities Code § 1203

Each corporation and political subdivision to which any of the expense is apportioned shall pay from the funds available therefor in its treasury the amount apportioned to it at the time and to the parties specified by the order of the commission. If that amount is not so paid the corporation or political subdivision entitled thereto under the order may sue therefor in any court of competent jurisdiction. If no such funds are available the appropriate boards, officers, and employees intrusted with the levy and collection of the taxes or assessments of such political subdivision shall do all acts necessary to include in the next succeeding tax or assessment levy the amount due and shall collect that amount, whereupon the amount due shall be paid in accordance with the commission’s order. The commission may by order designate the State, certain of the corporations, and political subdivisions affected, to do all or specified portions of the acts required by any order of the commission made under the provisions of Sections 1202 to 1205, inclusive, and may prescribe the manner and the time within which the parties so designated shall be paid or reimbursed by the other corporations, the State, and political subdivisions among which the expense of the work has been apportioned by the commission.