18 CFR § 4.1 - Initial cost statement.
(a) Notification of Commission. When a project is constructed under a license issued under the Federal Power Act, the licensee shall, within one year after the original project is ready for service, file with the Commission a letter, in quadruplicate, declaring that the original costs have been booked in compliance with the Commission's Uniform System of Accounts and the books of accounts are ready for audit.
(b) Licensee's books. The licensee's books of accounts for each project shall be maintained in such a fashion that each year's additions, betterments, and deletions to the project may be readily ascertained.
(c) Availability of information to the public. The information made available to the Commission in accordance with this section must be available to the public for inspection and copying when specifically requested.
(d) Compliance with the Act. Compliance with the provisions of this section satisfies the filing requirements of section 4(b) of the Federal Power Act (16 U.S.C. 797(b)).