HELIX Environmental Planning (HELIX) prepared an Environmental Impact Statement (EIS), Supplemental EIS, and prepared and managed supporting technical studies related to air quality/greenhouse gases, biological resources, cultural resources, hazardous materials, and community impacts for the reconfiguration and expansion of the existing San Ysidro Land Port of Entry (LPOE) at the U.S./Mexico border. The project would demolish most of the existing facilities, and new facilities would be constructed in three independent phases to improve overall capacity and operational efficiency at the LPOE. New facilities would include northbound primary and secondary inspection areas, an administration building, a pedestrian building, a central plant, one pedestrian bridge, a parking structure, and other support structures. Phase 1 primarily entails reconfiguration of the northbound facilities, Phase 2 involves construction of new buildings, and Phase 3 mainly would involve reconfiguration of the southbound facilities. HELIX provided public and agency outreach support to the U.S. General Services Administration (GSA), the NEPA lead agency for the project. The EIS and SEIS were successfully completed on an accelerated schedule to meet funding obligations. HELIX also prepared a Mitigation Monitoring and Enforcement Program (MMEP) for this project, the first of its kind implemented by GSA District IX. The MMEP addressed the avoidance, minimization, and mitigation measures identified in the Record of Decision for the San Ysidro LPOE project and identified the timing, responsibility, and method of implementation of the proposed measures and required monitoring or enforcement activities.