Participating agency. A Federal, State, local, or federally recognized Indian Tribal governmental unit that may have an interest in the proposed project and has accepted an invitation to be a participating agency or, in the case of a Federal agency, has not declined the invitation in accordance with 23 U.S.C. 139(3).
23 CFR § 771.107
The definitions contained in the CEQ regulations and in titles 23 and 49 of the United States Code are applicable. In addition, the following definitions apply to this part.