18 CFR 12.11 - Reporting modifications of the project or project works.
(a) Reporting requirement. Regardless of whether a particular modification is permitted without specific prior Commission approval, an applicant or licensee must report any modification of the project or project works to the Regional Engineer in writing, verified in accordance with § 12.13, at the time specified in paragraph (b) of this section.
(b) Time of reporting.
(1) Any modification that is an emergency measure taken in response to a condition affecting the safety of the project or project works must be submitted with the report of that condition required by § 12.10(a)(2).
(2) In all other instances, the modification must be reported at least 60 days before work on the modification begins.