Cal. Water Code § 23263

For the purpose of providing the necessary money to carry on the construction work the district may borrow money for a term not exceeding five years at rates of interest, to be fixed by its board, not exceeding 7 per cent per year and issue notes, warrants, or other evidences of indebtedness therefor. The aggregate amount of the indebtedness shall at no time exceed one-half of the total construction cost as provided in the construction contract.