The first step in the NEPA environmental review process is to identify the proposed action.
After you have identified the proposed action then you must determine the level of NEPA review. The levels of NEPA review are: Statutory Exclusion (STATEX); Categorical Exclusion (CATEX); Environmental Assessment (EA) and Environmental Impact Statement (EIS).
If the project can be Statutorily Excluded (STATEX) then you must still comply with all other environmental laws and Executive Orders. Such as: Endangered Species Act; Wild & Scenic Rivers Act; Farmland Protection Act; EO 11988-Floodplains Protection; Clean Water Act; National Historic Preservation Act; Archeological & Historic Preservation Act; EO 11990-Wetlands Protection; EO 12898-Environmental Justice and the Clean Air Act.
If the proposed action cannot be Statutorily Excluded (STATEX) then can it be Categorically Excluded (CATEX)? If the proposed action can be Categorically Excluded then you must determine if there are Extraordinary Circumstances. If no Extraordinary Circumstances exist then there is an Administrative Record and agency action occurs. If Extraordinary Circumstances do exist then you must do an Environmental Assessment (EA).
If an Environmental Assessment (EA) must be written, then you have to determine if there are going to be significant impacts or controversy involved in the proposed action. If no significant impacts or controversy exist then the EA is written with a Finding of No Significant Impact (FONSI) and agency action occurs. If significant impacts or controversy exist then you must do an Environmental Impact Statement (EIS).
If an Environmental Impact Statement must be written then a Record of Decision (ROD) is the outcome. This ROD is documented and agency action occurs.