Sec. 13.131. RECORDS OF UTILITY; RATES, METHODS, AND ACCOUNTS

(a) Every water and sewer utility shall keep and render to the regulatory authority in the manner and form prescribed by the commission uniform accounts of all business transacted. The commission may also prescribe forms of books, accounts, records, and memoranda to be kept by those utilities, including the books, accounts, records, and memoranda of the rendition of and capacity for service as well as the receipts and expenditures of money, and any other forms, records, and memoranda that in the judgment of the commission may be necessary to carry out this chapter.

(b) In the case of a utility subject to regulation by a federal regulatory agency, compliance with the system of accounts prescribed for the particular class of utilities by that agency may be considered a sufficient compliance with the system prescribed by the commission. However, the commission may prescribe forms of books, accounts, records, and memoranda covering information in addition to that required by the federal agency. The system of accounts and the forms of books, accounts, records, and memoranda prescribed by the commission for a utility or class of utilities may not conflict or be inconsistent with the systems and forms established by a federal agency for that utility or class of utilities.

(c) The commission shall fix proper and adequate rates and methods of depreciation, amortization, or depletion of the several classes of property of each utility and shall require every utility to carry a proper and adequate depreciation account in accordance with those rates and methods and with any other rules the commission prescribes. Rules adopted under this subsection must require the book cost less net salvage of depreciable utility plant retired to be charged in its entirety to the accumulated depreciation account in a manner consistent with accounting treatment of regulated electric and gas utilities in this state.