(a) The possible environmental effects of a proposed action or project must be considered along with technical, economic, and other factors throughout the decisionmaking process. For most Corporation projects there are three distinct stages in the decision making process:

(1) Conceptual or preliminary stage;

(2) Detailed planning or final approval stage;

(3) Implementation stage.

(b) Environmental review will be integrated into the decision making process of the Corporation as follows:

(1) During the conceptual or preliminary approval study stage, the responsible Corporation official shall determine whether the proposed action or project is one which is categorically excluded, requires an environmental assessment or an EIS.

(2) Prior to proceeding from the conceptual or preliminary approval stage to the detailed planning or final approval stage, an environmental assessment and the determination as to whether an EIS is required must be completed.

(3) An EIS, if determined necessary, must be completed and circulated prior to the decision to proceed from the detailed planning stage to implementation.