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Highway 1 Elkhorn Slough Corridor Resiliency Project

Highway 1 Elkhorn Slough Corridor Resiliency Project

The Highway 1 Elkhorn Slough Corridor Climate Resiliency Project ("the Project") study area is under threat from projected sea level rise and increased frequency of extreme weather events. Highway 1 could potentially be rendered unstable, threatening local businesses and residents, particularly in Moss Landing. The Transportation Agency for Monterey County (TAMC), in collaboration with The Nature Conservancy (TNC) and the Elkhorn Slough National Estuarine Research Reserve (ESNERR), is leading a Planning and Environmental Linkages (PEL) Study to evaluate the viability of alternative transportation options and establish community-supported consensus for the future of the corridor. 

View the project fact sheet here. Learn about the current project status by reading the Summer 2026 Newsletter in English or Spanish or by viewing the Project Timeline and Meetings & Events tabs. 

Watch the video below to see how high tides are impacting Elkhorn Slough, Highway 1, and the railroad today.

Contact Information

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The success of this project depends on the input, insights, and collaboration of local residents, businesses, environmental advocates, and other stakeholders who know and value this unique corridor. Your perspectives will help shape solutions that not only address flooding risks and infrastructure needs but also reflect the priorities of those who live, work, and travel through the area. 

Participate now by filling out this 5-minute survey English or Spanish or by adding a comment to this interactive map of the project area!

The Project is utilizing outreach to a range of groups of interested partner agencies, non-profit organizations, community-based organizations, and the public to gather feedback on existing conditions, alternatives and how TAMC should screen the alternatives developed.

 

Project Area Map

Project Goals

This project is focused on addressing the urgent challenges facing the Elkhorn Slough because of sea level rise and environmental degradation of the estuary. By implementing community-supported and technically feasible infrastructure improvements, the plan aims to protect vital ecosystems, enhance transportation connections and safety, and support the communities that rely on the estuary. Key goals for this effort include the following: 

  • Improve Highway 1 infrastructure by providing congestion relief and improved safety and mobility for drivers, pedestrians, and cyclists

  • Prepare the Project for future local, state, and federal grant opportunities  

  • Reduce tidal flooding and enhance restoration efforts to the Elkhorn Slough Natural Estuarine Reserve (ESNERR)

  • Ensure the long-term resilience  of the critical transportation corridor and mitigating flooding issues to the project corridor that could affect local communities and businesses

 

Project Background

Elkhorn Slough is the third largest span of tidal wetlands in California and is home to more than 700 species, including 135 aquatic birds, 550 marine invertebrate species, and 102 fish species.  The area’s significance to the region has long been recognized as a critical ecosystem and the current rate and type of sea level rise could threaten its stability, potentially leading to the loss of up to 85% of this habitat.  Elkhorn Slough’s salt marshes are highly vulnerable due to human impacts over the past 150 years that have weakened its natural resilience beginning with the introduction of artificial tidal restrictions through diking and draining of the wetlands. The development of Moss Landing Harbor accelerated this decline in the 1950’s by deepening the main channel and increasing tidal erosion, causing extensive marsh loss.

The Central Coast Highway 1 Resiliency Study , led by the Association of Monterey Bay Area Governments (AMBAG), found that by 2050, two feet of sea level rise would cause major disruptions to Highway 1, further degrade the marshland, harm the surrounding farms, and increase the number of properties at risk of coastal flooding. Explore the project area and learn more about related projects on the Regional Resilience tab. TAMC received funding for the Highway 1 Elkhorn Slough Corridor Climate  Resiliency Project from Caltrans in July of 2024 to conduct this work. TAMC will analyze current conditions, evaluate potential solutions, and select a preferred alternative that meets both transportation and environmental needs.