18 C.F.R. § 5.21
An applicant may be required to submit any additional information or documents that the Commission considers relevant for an informed decision on the application. The information or documents must take the form, and must be submitted within the time, that the Commission prescribes. An applicant may also be required to provide within a specified time additional copies of the complete application, or any of the additional information or documents that are filed, to the Commission or to any person, agency, Indian tribe or other entity that the Commission specifies. If an applicant fails to provide timely additional information, documents, or copies of submitted materials as required, the Commission may dismiss the application, hold it in abeyance, or take other appropriate action under this chapter or the Federal Power Act.
18 C.F.R. § 5.21