Self-Governance Tribes assume environmental responsibilities by:
(a) Adopting a resolution or taking an equivalent Tribal action which:
(1) Designates a certifying officer to represent the Self-Governance Tribe and to assume the status of a responsible Federal official under NEPA, NHPA, and related provisions of law; and
(b) Entering into a construction project agreement under section 509 of the Act [25 U.S.C. 458aaa-8].