The Board of Supervisors may establish and provide for a capital reserve fund to pay in full or in part for public improvements, replacement of worn-out buildings and equipment, and planned and unplanned major repairs of a management facility, in furtherance of the purpose for which the District was created. Any such capital reserve fund shall be kept in a separate account and invested as are other public funds and shall be expended for such purposes for which established. The cost of payments to any capital reserve fund shall be included in the annual budget of the District.