In March 2003, CBP issued a final Environmental Assessment (EA) that addressed fence, roads, low water crossings, and wells at various locations along the border from Tecate to the Imperial County line. Included in these actions was a road on the west slope of Airport Mesa. In November 2003, CBP released a Final Supplemental Environmental Assessment (SEA) that addressed some changes to the March 2003 project and added some new project components. Included in the changes was a new alignment on the western slope of Airport Mesa, which would reduce the overall project footprint, avoid some washes, and reduce the costs.

Between November 2003 and 2006, CBP tried unsuccessfully to purchase the land on the western slope of Airport Mesa. CBP then arranged with the Bureau of Land Management (BLM) for an easement and new design on the eastern slope of Airport Mesa, a design which further reduced the project footprint. In July 2007, a draft SEA was released to the public and addressed this new alignment only (i.e., other components in the November 2003 SEA remained the same). No public comments were received. However, CBP revised the EA and resubmitted it for public review.

During the time period for revisions to this draft SEA, CBP implemented the Project Fence 225 (PF225) program in response to Congressional mandates. In April 2008, the Secretary of the Department of Homeland Security issued the waiver of certain environmental laws and this SEA was used as the basis for an Environmental Stewardship Plan (ESP) in keeping with the Secretary's commitment to complete an "environmental review" prior to major construction.