Interstate 5 (I-5) Improvement Project from Interstate 405 (I-405) to State Route 55 (SR-55)

The Interstate 5 Improvement Project, managed by the California Department of Transportation (Caltrans) District 12 in Orange County, involves expanding the highway between I-405 and SR 55. The scope of work includes constructing additional travel lanes in both northbound and southbound directions, re-establishing existing auxiliary lanes, building new auxiliary lanes, improving on- and off-ramps, and widening several structures. The project is located within the cities of Irvine and Tustin and crosses multiple waterways, including San Diego Creek, Bee Canyon Channel, Marshburn Channel, and the Peters Canyon Flood Control Channel. Under Lake and Streambed Alteration Agreement EPIMS-ORA-43374-R5, the project includes the reconstruction of eighteen channel locations and the addition of a temporary water diversion at Project Stream Location 10. The California Department of Fish and Wildlife (CDFW) acted as the Responsible Agency and approved the project on June 16, 2026, determining that it would not have a significant environmental effect within its jurisdiction. This approval is contingent upon the implementation of specific mitigation measures and a Mitigation Reporting or Monitoring Plan adopted by the CDFW.