Project Description:

Elkhorn Slough is a major estuary that serves as a vital ecosystem for regional biodiversity, contains an important transportation corridor for the Central Coast, and is home to numerous small communities and businesses. The area is a habitat for hundreds of species and borders five miles of Union Pacific Railroad tracks and an eight-mile stretch of Highway 1, the key coastal route between Monterey and Santa Cruz counties. This crucial infrastructure provides essential freight access to the Moss Landing Harbor District, Monterey’s number one fishing port.    

As a result of projected sea level rise and increased frequency of extreme weather events, this unique area is at great risk of flooding, prompting the need for the Elkhorn Slough Corridor Project to address these interconnected challenges and develop solutions to protect this region. By implementing a Planning and Environmental Linkages (PEL) Study, the Transportation Agency for Monterey County (TAMC), in collaboration with The Nature Conservancy (TNC) and the Elkhorn Slough National Estuarine Research Reserve (ESNERR), will be leading the effort to evaluate the viability of alternative transportation options and establish a community-supported consensus around how to protect the region into the future. Image of Elkhorn Slough

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.  

While sea level rise projections are still being evaluated, there is a clear trend that the expected levels of increased water would have an irreversibly negative impact on the area. Highway 1 could potentially be rendered unstable, threatening local businesses and residents, particularly Moss Landing, with forced displacement. Additionally, critical habitat could be permanently damaged. 

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. 

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. 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.

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 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 for drivers, pedestrians, and cyclists

  • Prepare Elkhorn Slough  Resiliency Project for future local, state, and federal grant opportunities  

  • Reduce tidal flooding and dangers to the Elkhorn Slough Natural Estuarine Reserve (ESNERR)

  • Protect the local communities and businesses in the area by ensuring the long-term resilience  of the critical transportation corridors and mitigating flooding issue​

​Partners and Advisors

  • Partners and Advisors/Collaborators 
  • Agricultural Property Owners/Neighbors
  • Community Based Outreach Groups
  • Commuters
  • Elected Officials
  • Environmental Groups
  • Equity/EJ focused   
  • Governmental Agencies
  • Hospitality Industry
  • Non-Agricultural Property Owners/Neighbors
  • Railroad Companies  
  • Tribal Governments

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