Be it further enacted, That separate financial and accounting records shall be maintained to show the financial operation and condition of each utility, in accordance with generally accepted principles of utility accounting and as may be required by the city council. Such records shall be maintained by each utility as prescribed by the director of finance, with the approval of the city manager, and an annual financial and administrative report on each utility shall be submitted to the city manager at such time and in such form as the council may require. The director of finance may require, periodically, each utility to furnish summary data for general accounts maintained in his office. If required by the council, all such accounts and records may be maintained in the department of finance, based on data furnished by each utility.