If at any time during the fiscal year the County Executive shall ascertain that available revenue for the fiscal year may be less than the total appropriations, the County Executive shall reconsider the appropriations for all of County agencies developed pursuant to Section 817 of the Charter and submit a proposed supplementary appropriation for use of funds from the Revenue Reserve Account Fund to the Council in accordance with Section 815 of the Charter. All interest income attributable to the Fund shall be retained in the Fund.