The Board of Supervisors may establish and provide for a sinking Fund, however denominated, for the retirement of bond issue or other debt, or to provide security for the payment thereof. When so established, it shall be kept intact and separate from other monies at the disposal of the District, and shall be accounted for as a pledged asset for the purpose of retiring or securing such obligations. The cost of payments to any sinking fund shall be included in the annual budget of the District.