Marin 101 Sea Level Rise Adaptation Planning Study

As documented in the Caltrans District 4 Vulnerability Assessment (2019) and Adaptation Priorities Report (2020) future sea level rise and associated impacts are projected to impact specific locations within the study area. Furthermore, episodic flooding and damage caused by high tide and storm surge are present-day impacts the corridor is already affected by, which hinders safe and unimpeded access for travelers who utilize this US 101 corridor. The purpose of this study is to develop a long-term sea level rise adaptation plan for a portion of the US 101 highway corridor in Marin County using the principles of phased adaptation to build resilience over time, and robust coordination with permitting agencies, stakeholders, and public engagement to inform project development within the project limits. This study will provide essential preliminary planning information Caltrans can use to move towards initiating an adaptation project, or a set of projects, along this vulnerable corridor. The study will build upon existing and previous local planning efforts, identify possibilities for feasible and implementable, interim, and long-term solutions within the study location, establish screening criteria with robust public engagement and preliminary consultation from regulatory agencies, and identify strategies to advance project programming and development for current and future Caltrans projects on US 101 in Marin County. This study shall apply a combination of sea level rise analysis/alternatives assessment work with public engagement/outreach, implementing these two (2) activities strategically - either independently or in tandem - at specific locations through the larger corridor-level study area.