Cal. Sts. & Hy. Code § 5171
Before requiring the plans, specifications and estimates provided for in Section 5130 the legislative body shall pass a resolution requesting the public agency having charge of the supplying and distribution of the domestic water supply in the district about to be improved to furnish to the legislative body plans and specifications for adequate and appropriate conduits, pipes, hydrants and other appurtenances necessary for that purpose. It shall be the duty of such public agency to furnish the plans and specifications so required, and the plans and specifications shall be submitted to the legislative body for its approval. The cost of the preparation of such plans and specifications shall form a part of the incidental expenses of the work.
Ca. Sts. and High. Code § 5171