All airport development funds appropriated by the legislature for any fiscal year or carried forward from any fiscal year, and not encumbered by specific intergovernmental agreements approved by the commission, shall be available to supplement existing grant or loan agreements to meet unforeseen costs. The executive director or his or her designee not below the director may authorize supplemental grants or loans to cover costs not exceeding 25% of the total grant contract or loan approved by the commission or $100,000, whichever is greater.