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Cal Poly Humboldt Technical Memos Released
January 2026
Caltrans is preparing a Comprehensive Adaptation and Implementation Plan (CAIP) for U.S. 101 between Eureka and Arcata to meet the requirements of a Coastal Development Permit (CDP) issued by the California Coastal Commission for the Eureka/Arcata Corridor Improvement Project.
To support this plan, District 1 partnered with Cal Poly Humboldt (CPH) to study current and future climate conditions, understand the risks of taking no action under different sea level rise (SLR) scenarios, and evaluate possible adaptation strategies for the corridor using the best available sea level rise science.
As part of this work, CPH prepared a series of technical memoranda. View them on the Eureka/Arcata Corridor page.
Mendocino County Sea Level Rise Roadway Impact Study
October 2025
MCOG is pleased to announce the launch of the project website for the Mendocino County Sea Level Rise Roadway Impact Study: www.MendocinoSLRstudy.org
This website will serve as the central hub for information about the study, including background on the project, timeline, upcoming engagement opportunities, and ways the public can get involved. Visitors can also sign up to receive project updates and share input with the project team.
Transforming Sea Level Rise Into An Opportunity
October 2023
When Jason Patton bikes from his home in Manila, California, to the nearby town of Arcata, he rides along a peninsula at the edge of Humboldt Bay. His travels lead past levees that were built in the late 1880s to protect this narrow slip of land from the sea. But lately, their protection has started to feel precarious.
Caltrans welcomes you to our online resources to help you stay informed regarding our planning and project efforts in District 1. You can find information regarding our efforts along the Highway 101 Corridor and in each of the 4 counties covered by District 1.
Map of Counties
There are 23 state highways located within District 1. In many of these areas, the State Highway System (SHS) serves as the “main street.” The SHS also provides outlying communities access to emergency services.
To view the locations along the SHS that are the most at-risk due to climate change, click the link below.