As soon as it appears that income is less than anticipated, the Council shall amend the general appropriations ordinance to keep expenditures within the cash income as provided by State law. In any event, at the beginning of each quarter during the fiscal year and more often if required by Council, the City Manager shall submit data to the Council showing the relation between the estimated and actual income and expenses to date. If the revenues should exceed the amounts estimated in the budget, the Council may make supplemental appropriations.