(a) A lead agency shall supervise the preparation of an environmental impact statement or environmental assessment if more than one Federal agency either:

(1) Proposes or is involved in the same action; or

(2) Is involved in a group of actions directly related to each other because of their functional interdependence or geographical proximity.

(b) A Federal, State, Tribal, or local agency may serve as a joint lead agency to prepare an environmental impact statement or environmental assessment (§ 1506.2 of this subchapter). A joint lead agency shall jointly fulfill the role of a lead agency.

(c) If an action falls within the provisions of paragraph (a) of this section, the participating Federal agencies shall determine, by letter or memorandum, which agency will be the lead agency, considering the factors in paragraphs (c)(1) through (c)(5) of this section, and the lead agency shall determine which agencies will be joint lead or cooperating agencies. The agencies shall resolve the lead agency question so as not to cause delay. If there is disagreement among the agencies, the following factors (which are listed in order of descending importance) shall determine lead agency designation:

(1) Magnitude of agency's involvement;

(2) Project approval or disapproval authority;

(3) Expertise concerning the action's environmental effects;

(4) Duration of agency's involvement; and

(5) Sequence of agency's involvement.

(d) Any Federal, State, Tribal, or local agency or person substantially affected by the absence of a lead agency designation, may make a written request to the senior agency officials of the potential lead agencies that a lead agency be designated. An agency that receives a request under this paragraph shall transmit such request to each participating Federal agency and to the Council.

(e) If Federal agencies are unable to agree on which agency will be the lead agency or if the procedure described in paragraph (c) of this section has not resulted in a lead agency designation within 45 days of the written request to the senior agency officials, any of the agencies or persons concerned may file a request with the Council asking it to determine which Federal agency shall be the lead agency. The Council shall transmit a copy of the request to each potential lead agency. The request shall consist of:

(1) A precise description of the nature and extent of the proposed action; and

(2) A detailed statement of why each potential lead agency should or should not be the lead agency under the criteria specified in paragraph (c) of this section.

(f) Any potential lead agency may file a response no later than 20 days after a request is filed with the Council. As soon as possible, but not later than 40 days after receiving the request, the Council shall designate which Federal agency will be the lead agency and which other Federal agencies will be cooperating agencies.

(g) To the extent practicable, if a proposal will require action by more than one Federal agency and the lead agency determines that the proposal requires preparation of an environmental impact statement, the lead and cooperating agencies shall evaluate it in a single environmental impact statement; the lead and cooperating agencies shall issue, except where inappropriate or inefficient, a joint record of decision. To the extent practicable, if a proposal will require action by more than one Federal agency and the lead agency determines that it requires preparation of an environmental assessment, the lead and cooperating agencies shall evaluate the proposal in a single environmental assessment and issue a joint finding of no significant impact or jointly determine to prepare an environmental impact statement.

(h) With respect to cooperating agencies, the lead agency shall:

(1) Request the participation of each cooperating agency in the NEPA process at the earliest practicable time;

(2) Consider any analysis or proposal created by a cooperating agency and, to the maximum extent practicable, use the environmental analysis, proposal, and information provided by cooperating agencies;

(3) Meet with a cooperating agency at the latter's request; and

(4) Determine the purpose and need, and alternatives in consultation with any cooperating agency.