Marshes on the Margin

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Marshes on the Margin

Developing Tidal Wetlands Adaptation Strategies in Southern California

Through the  Marshes on the Margin we are investigating how the dynamic and heavily altered estuaries of Southern California will be affected by sea level rise. Project partners are also working to identify nature-based conservation and restoration strategies to mitigate the impacts of sea level rise, and will share the tools developed with local stakeholders and coastal managers.

Why we care

Historically, approximately 98 percent of tidal wetlands in Southern California were intermittently open to tidal action. The diverse and seasonally varying habitats provided by intermittently open estuaries serve a wide variety of estuarine species. However, very few estuaries in Southern California still exhibit natural cycles of intermittency, and many are managed as permanently open systems either through construction of jetties, or through dredging.

The conversion from intermittent dynamics to permanently open leads to a reduction of habitat diversity in the region and a reduction in the support of certain NOAA trust species, such as tidewater gobies and juvenile steelhead. Wetlands around these estuaries also host a number of endangered and threatened plant and animal species. Very little data and understanding exists about intermittently open estuaries in Southern California, and resource managers frequently need better information to make management decisions. Because the patterns of opening and closure in tidal wetlands is likely to change with rising sea levels, we have an opportunity and a need to rethink management of these systems, and to better understand the trade-offs between various management scenarios.

What we are doing

Our project will have four stages: 

  • Identifying the vulnerability of intermittently open estuaries,
  • Developing natural and nature-based adaptive strategies
  • Implementing these developed tools at case study sites, and
  • Leveraging existing coastal management networks to share outcomes and promote management solutions that rely on natural and nature-based features.

First, the project team will model and analyze the vulnerabilities and response of intermittently open estuaries and tidal wetlands to sea level rise. Next, the team will identify opportunities for natural restoration through construction of nature-based features. The tools are being applied at four wetland systems in Southern California, including:

  • Goleta Slough (Santa Barbara County)
  • Los Cerritos (Orange and Los Angeles Counties)
  • Los Peñasquitos Lagoon (San Diego County)
  • Tijuana River & Estuary (San Diego County)

Finally, the project team will leverage existing scientific, management, and practitioner networks, developed through the Southern California Wetlands Recovery Project, to gain input during the project’s product development stage and to promote inclusion of natural and nature-based features in the wider range of adaptation strategies available to coastal managers. These steps are expected to improve the number of tools available for managing intermittently open estuaries in Southern California.

Project partners include the California State Coastal Conservancy (South Coast Region), Climate Science Alliance – South Coast, Point Blue Conservation, San Francisco Estuary Institute, Southern California Coastal Water Research Project, Tijuana River National Estuarine Research Reserve, U.S. Geological Survey, University of California- Davis, and University of Southern California Sea Grant. This project builds on the collaborative work of the Southern California Wetlands Recovery project partnership, and  is funded through NOAA’s funded through the Ecological Effects of Sea Level Rise (EESLR) Program.

Engagement at case study sites

Introductory meetings are being held at each individual case study site and are designed to ensure:

  • Marshes on the Margins project team better understand each specific site and stakeholder needs
  • Stakeholders understand Marshes on the Margins project and approaches
  • A shared understanding of the use of each site as a case study site is developed

Meetings have included:

  • Los Peñasquitos Lagoon (San Diego County) – March 21, 2018
  • Los Cerritos (Orange and Los Angeles Counties) – June 4, 2018

Management Transition Advisory Group (MTAG)

The MTAG is made up of Southern California wetland resource managers who have unique knowledge of local wetlands, and additional key stakeholders, including local government representatives, whose decisions directly affect the resilience of wetlands in the face of climate change and sea level rise.

Transition Zones & the Future of Restoration

August 14th | Metropolitan Water District, 700 Alameda St. Los Angeles, 90012


  • Increase understanding of transition zones and resilience, and their role in the Regional Strategy Update (RSU).
  • Increase understanding of different local transition zone types, and in the context of sea level rise, what future opportunities exist and solutions are viable for each type.
  • Discuss opportunities, challenges, and priorities of implementing different management measures that restore transition zones.

Workshop materials

  • Presentation – Jeremy Lowe, San Francisco Estuary Institute
  • Workbook

Follow-up Resources