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

The California Department of Transportation is undertaking a major improvement project along Interstate 5 between Interstate 405 and State Route 55, which includes adding a new travel lane in both northbound and southbound directions, re-establishing and constructing auxiliary lanes, upgrading existing on- and off-ramps, and widening multiple structures. The project also involves reconstructing eighteen stream channel locations to enhance functionality and safety, with a specific amendment to the Lake and Streambed Alteration Agreement allowing for a temporary water diversion at Stream Location 10 to facilitate construction activities. These modifications are carried out under the authority of the Fish and Game Code section 1602 and are coordinated through the California Department of Fish and Wildlife. The project is managed by Caltrans District 12 - Orange, with environmental oversight provided by the California Department of Fish and Wildlife. Key contacts include Fawne Yamashiro as Project Manager and Andrew Domingos as Environmental Scientist, who oversee coordination and compliance with regulatory requirements. The project was formally forecasted on June 19, 2026, and all work is targeted to occur within Orange County, California, with environmental mitigation measures integrated into the construction plan to minimize ecological disruption.