4 j 16 action relates only to a part of the project. In some cases it ‘will be most efficient for the agencies involved to agree on a single lead agency to prepare the statement on the entire project, obtaining assistance as necessary from the other agencies involved or from other agencies with relevant expertise. Relevant factors in determining the proper agency to assume such a role include: the time sequence in which the agencies become -involved. in the project, the magnitude of their respective involvement, and their relative expertise with respect to the project's environmental effects. But these criteria are not absolute and do not foreclose either a cooperatively prepared state- ment, or advance agreement on designation of a “lead agency" for purposes of ensuring leadership -.-@nd assigning gesponsiibility. . Whichever. procedure ~ eeee — is followed;thetwo.critical_considerations— = ~3ysdnherent-:-in-ithéprovisions”Of-‘Séction—"Sb)carer! (1) evaluation of the entire’“project;- and” (2}— Satoabeeee preparation of the 102 .statement before any of the participating agencies has taken major or irreversible action with respect to the project. See Upper Pecos Ass'n v. Stans, 2 ERC 1418 (10th Cir. 1971), pet'n. for cert. pending, 40 USLW 3444 Ne. Ti11334: Mar 6, 1972). -- _ ~ = > Te Recommendation #8: In- resolving "lead agency" questions,..agencies should consider the possibility of joint preparation of a state- ment by all agencies involved, as well as _designation of a single agency to assume leadership responsibilities in preparing the statement. In either case, the statement should contain-an environmental evalua- Bao o> a) (= tion of the entire project, and-‘should be prepared before major or irreversible actions have been taken by any of the participating agencies.