The board may in each fiscal year set aside in separate funds out of the revenues of the works a sufficient sum to:
(a) First, pay the operating expenses of the district.
(b) Second, provide for repairs and maintenance of the works owned or operated by the district, including any payments to be made into a replacement fund for buses and ferries.
(c) Third, provide for the purchase, lease, or other acquisition of district equipment, supplies, and other properties, including provision for interest, sinking funds, reserve funds, or other funds required for the payment of any obligations incurred by the district for the acquisition of such properties.
(d) Fourth, pay any indebtedness or lien that may exist against the district or any of its property or revenues.
The revenues of the works are hereby pledged to the aforesaid purposes.