; and (bb) communicate any issues described in item (aa) to the project sponsor. (V) Elevation for missed milestone If a dispute between the Secretary and participating agencies (or amongst participating agencies) causes a milestone to be missed or extended, or the Secretary anticipates that a permitting timetable milestone will be missed or will need to be extended, the dispute shall be elevated to an official designated by the relevant agency for resolution. The elevation of a dispute shall take place as soon as practicable after the Secretary becomes aware of the dispute or potential missed milestone. (VI) Exception Disputes that do not impact the ability of an agency to meet a milestone may be elevated as appropriate. (VII) Further evaluation If a resolution has not been reached at the end of the 30-day period after a relevant milestone date or extension date after a dispute has been elevated to the designated official, the relevant agencies shall elevate the dispute to senior agency leadership for resolution. (D) Consistency with other time periods A schedule under subparagraph (C) shall be consistent with any other relevant time periods established under Federal law. (E) Modification (i) In general Except as provided in clause (ii), the Secretary may lengthen or shorten a schedule established under subparagraph (C) for good cause. The Secretary may consider a decision by the project sponsor to change, modify, expand, or reduce the scope of a project as good cause for purposes of this clause. (ii) Limitations (I) Lengthened schedule The Secretary may lengthen a schedule under clause (i) for a cooperating Federal agency by not more than 1 year after the latest deadline established for the project described or designated under subsection (b) by the Secretary. (II) Shortened schedule The Secretary may not shorten a schedule under clause (i) if doing so would impair the ability of a cooperating Federal agency to conduct necessary analyses or otherwise carry out relevant obligations of the Federal agency for the