65 ILCS 5/11-122-5
Every city owning, or owning and operating, street railways, shall keep the books of account for these street railways distinct from other city accounts and in such manner as to show the true and complete financial results of the city ownership, or ownership and operation, as the case may be. These accounts shall be so kept as to show: (1) the actual cost to the city of street railways owned, (2) all costs of maintenance, extension, and improvement, (3) all operating expenses of every description, in case of city operation, (4) the amount set aside for sinking fund purposes, (5) if water or other service is furnished for the use of the street railways without charge, as nearly as possible, the value of this service, and also the value of any similar service rendered by the street railways to any other city department without charge, (6) reasonable allowances for interest, depreciation, and insurance, and (7) estimates of the amount of taxes that would be chargeable against the property if owned by a private corporation. The city council shall print annually for public distribution, a report showing the financial results, in the form specified in this section, of the city ownership, or ownership and operation.
The accounts of those street railways, shall be examined at least once a year by a licensed Certified Public Accountant permitted to perform audits under the Illinois Public Accounting Act , who shall report to the city council the results of his examination. This accountant shall be selected in such manner as the city council may direct, and he shall receive for his services such compensation, to be paid out of the income from those street railways, as the city council may prescribe.
65 ILCS 5/11-122-5