general If there are 2 or more involved Federal agencies that have authority with respect to a proposed agency action, the involved Federal agencies shall determine, by letter or memorandum, which Federal agency shall be the Federal lead agency based on consideration of the following factors: (A) Magnitude of the involvement of each Federal agency. (B) Special expertise concerning the effects of the proposed agency action. (C) Duration of the involvement of each Federal agency. (2) Joint lead agencies (A) In general In making a determination under paragraph (1), the involved Federal agencies may appoint State, Tribal, or local agencies as joint lead agencies, as determined appropriate by the involved Federal agencies. (B) Roles Joint lead agencies shall jointly fulfill the role described in paragraph (3). (3) Role A lead agency shall, with respect to a proposed agency action— (A) supervise the preparation of an environmental document if, with respect to the proposed agency action, there is more than 1 involved Federal agency