The National Nuclear Security Administration (NNSA), an agency within the DOE, announced its intent to prepare a supplemental site-wide environmental statement (S–SWEIS) to update the analyses presented in the Final Site-Wide Environmental Impact Statement for Continued Operation of the Los Alamos National Laboratory (SWEIS) (DOE/EIS–0238; January 1999).

Multiple comments were received regarding the type of NEPA document that NNSA should prepare, including comments calling for the development of a new SWEIS, rather than a supplement to the 1999 SWEIS (EIS-0238). In response, NNSA announced the preparation of a new SWEIS (EIS-0380), instead of the Supplemental SWEIS originally proposed.