Any borrower issuing revenue bonds under the provisions of this chapter shall install and maintain proper books of record and account (separate entirely from other records and accounts of such borrower) in which full and correct entries shall be made of all dealings or transactions of or in relation to the properties, business and affairs of the system, project or combined system. The governing body of such borrower, not later than three months after the close of any calendar, operating or fiscal year, shall cause to be prepared a balance sheet and an income and surplus account, showing, respectively, in reasonable detail the financial condition of the system, project or combined system at the close of such preceding calendar, operating or fiscal year and the financial operations thereof during such year. Such balance sheets and income and surplus accounts shall at all reasonable times during usual business hours be open to examination and inspection by any taxpayer, user of the services furnished or holder of bonds issued under the provisions of this chapter or anyone acting for or on behalf of such taxpayer, user or bondholder.