Where a district has an assessed valuation of less than one hundred thousand dollars ($100,000), the board of supervisors of the county may loan county funds, in a sum not in excess of ten thousand dollars ($10,000), to the district to be used for the purpose of repairing, improving, extending or renewing the district water system, to be returned to the county by the district from revenues and taxes of the district during the period of 10 years following the date of the loan.