The purpose of an environmental assessment is to allow the Responsible Official to determine whether to prepare an environmental impact statement or a finding of no significant impact.
(a) A bureau must ensure that an environmental assessment is prepared for all proposed Federal actions, except those:
(1) That are covered by a categorical exclusion;
(2) That are covered sufficiently by an earlier environmental document as determined and documented by the Responsible Official; or
(3) For which the bureau has already decided to prepare an environmental impact statement.
(b) A bureau may prepare an environmental assessment for any proposed action at any time to:
(1) Assist in planning and decision-making;
(2) Further the purposes of NEPA when no environmental impact statement is necessary; or
(3) Facilitate environmental impact statement preparation.