Feasibility Study- Garcia River
Feasibility Study- Garcia River
This study looks at ways to keep State Route 1 open during frequent flooding from the Garcia River, Gasker Slough, and Hathaway Creek. The goal is to find practical solutions that reduce road closures and make the highway safer and more reliable over time.
Overview
Project Information:
Background
The Garcia River rises very quickly during heavy rain, giving residents very little time to react before the road closes. If State Route 1 (SR 1) is flooded, the only other way to reach the other side of the river requires a 219‑mile detour that can take more than five hours. This detour is also dangerous due to landslides and sometimes snow.
When SR 1 closes, it affects travel in the region, emergency response, jobs, schools, health care, social services, and the local economy. Fire stations are on both sides of the river, but flooding reduces the number of units that can respond. The region’s only hospital is in Fort Bragg, 45 miles north of Point Arena. When flooding is expected, Manchester Elementary is notified and students are sent home.
To improve flood warnings for the community, Caltrans installed a live webcam at Hathaway Creek (the Gasker Slough Cam) and started a reverse‑911 alert system through Mendocino County in January 2017. These tools help, but they are temporary while Caltrans works on long‑term solutions for SR 1 flooding at the Garcia River.
Point Arena Mountain Beaver habitat has also been identified within the project area and will help shape study alternatives.
Purpose
The purpose of this study is to identify, develop, and compare adaptation strategies that will prevent or minimize road closures caused by perennial flooding from the Garcia River, Gasker Slough, and Hathaway Creek. The study aims to ensure long‑term mobility and safety on SR 1 by evaluating alternatives that improve coastal resilience and address vulnerabilities in the existing roadway and stream crossings.
Need
At least 25 overtopping events that resulted in road closures were recorded from 2005 through 2025 along SR 1 in Mendocino County, PM 17.50 – 18.60, where the highway runs adjacent to the Garcia River and Hathaway Creek. The existing road between Hathaway Creek and the Garcia River bridges is prone to flooding during and after storm events. Climate change and increased precipitation are expected to increase the frequency, severity, and duration of flooding. Without adaptation measures, this segment of SR 1 will face increasing closures, maintenance demands, and long‑term risk of roadway failure.
Map:
Alternative 1
Construct a viaduct/bridge west of the existing roadway.
Selected to avoid Point Arena Mountain Beaver habitat and to reduce highway curvature.
Alternative 2
Construct a viaduct/bridge along the existing roadway.
Selected to reduce impacts to parcel owners. Note that this alternative is immediately next to the highway to keep the highway open during construction.
Alternative 3
New roadway and bridge connecting to Windy Hollow Road.
Selected to retreat the road inland to higher elevation areas away from flood-prone areas.
Alternative 4
Hathaway Creek Bridge Replacement and Grade Raise.
Addresses chronic flooding of slower moving water and the majority of road closures in the Hathaway Creek/Gasker Slough area.
All alternatives merge to include this, but it is presented as a standalone alternative for a near-term solution & to separate out costs.
Your Voice Matters!
Caltrans wants to hear from you! Your feedback will help us understand the needs of the people who use and live near this corridor.
Just click the "Continue" button at the bottom of this page or the "Participate" tab at the top of this page.
"What is a feasibility study?"
A feasibility study is not a project, but rather a planning document scoping out the feasibility of potential alternatives.
STUDY TIMELINE
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