Humboldt 101 Drainage South

This project will rehabilitate drainage systems at 38 locations along U.S. 101 in Humboldt County approximately from the Mendocino County line to Rio Dell. It is necessary to preserve the roadway and prevent potential damage from storm events by repairing failing and deteriorated drainage systems that have exceeded their design life.

Project Description

The project would replace culverts, downdrains, drainage inlets, headwalls, endwall, and retaining walls, as well as install rock slope protection and rock-lined ditches.


The environmental phase of this project is currently underway with construction anticipated from fall 2024 to the end of 2026.

Traffic Impacts



Accessibility Assistance: Caltrans makes every attempt to ensure our documents are accessible. Due to variances between assistive technologies, there may be portions of this document which are not accessible. Where documents cannot be made accessible, we are committed to providing alternative access to the content. Should you need additional assistance, please contact us at (916) 654-2852 or visit  

For more information, contact:

Julie Price, Environmental Coordinator

(707) 362-5431

Myles Cochrane, Public Information (Media inquiries)

(707) 498-4272

Last reviewed: April 2023

A well worn drainpipe emerges from a hillside and winds through narrow trees before ending at a waterway. Rust covers half of the pipe. A Caltrans worker in an orange reflective vest and a white hardhat looks on.

A metal downdrain lays across a hill adjacent to U.S. 101 in Humboldt County.