The City Council shall maintain sufficient cash reserves for the purpose of placing the payment of operating expenses of the City on a cash basis. The reserves shall be built from any available sources, and in combination with anticipated revenues shall be sufficient to meet all lawful demands against the City. Transfers may be authorized by the City Council from one fund to another fund or funds in such amounts as may be required to place those funds as nearly as possible on a cash basis. In case of such transfers, monies shall be returned to the fund from which they were transferred as they become available.