Project Name
Bothin Marsh Adaptation
Designing for sea level rise resilience at Bothin Marsh
DECEMBER 15, 2025
Design Update
The Marin Open Space District and the Golden Gate National Parks Conservancy are continuing their work together to further develop designs for the Bothin Marsh Adaptation. We are currently preparing for CEQA, with CEQA public review targeted for 2027.
The Bothin Marsh Preserve managed by the Marin County Open Space District is one piece of a complex puzzle in this area of South Marin. Community outreach, design, and build will take place in multiple phases across several years. For future phases of work, the goal is to work collaboratively with the City of Mill Valley, CalTrans, Marin County Department of Public Works, Southern Marin Sanitary District, and others who own property or have regulatory oversight along this corridor.
NOVEMBER 3, 2022
Tam Junction Design Concepts Being Developed
As the potential future re-route for the pathway was studied in more detail, One Tam partners – Marin County Parks and Golden Gate National Parks Conservancy – received community feedback on design options for the Tam Junction connection.
Project partners were on the pathway October 31, November 15, and , November 16, 2022. They shared renderings of potential trail connector concepts, and answered questions. During this time, geotechnical consultants were also at Bothin to explore subsurface conditions along the pathway and in other areas of the marsh. Community feedback indicated:
- restoration of native plant habitat is a top priority
- a safer, wider, more accessible, and better-connected pathway is critical
- any potential trail connections or trailhead should not contribute to traffic congestion
- a trailhead with restrooms, drinking fountain, and simple features would be a welcome addition
SEPTEMBER 7, 2021
Conceptual Design Completed
The Bothin Marsh Open Space Preserve faces unprecedented challenges related to flooding and sea level rise over the next century. One Tam partners, Marin County Parks and Golden Gate National Parks Conservancy, in collaboration through the Evolving Shorelines Project have developed adaptation plans for the Preserve to ensure that the rich habitats and public access trails throughout the site are resilient to future sea level rise using nature-based solutions that enhance the ecosystem and benefit the broader community. This report documents the adaptation planning and design process that would serve as the foundation for more detailed design development.
OCTOBER 15, 2020
Adaption Concept Recommendations
Project partners presented three draft concepts, and recommended "Ringing the Marsh" as the favored approach for preserving the marsh and protecting the pathway. Based on community feedback received via emails, virtual events, and an online survey, an overwhelming majority supported the concept Ring the South Marsh. Removing the trail from the marsh and re-aligning it to the perimeter of the Preserve will afford the greatest opportunity for enhancing the tidal marsh, and provides design elements that include physical separation from roads and the trail, maintaining an inviting visual experience of the marsh. View a short video explaining each concept:
- Ring the Marsh recommended concept video [External]
- Span the Marsh alternative concept video [External]
- Raise Trail in Place alternative concept video [External]
SUMMER 2921
Community Survey Report
In 2021, One Tam received about 850 responses to an online community survey soliciting feedback about conceptual approaches to elevating the Mill Valley-Sausalito Multiuse Pathway and enhancing the resiliency of Bothin Marsh. Results were included in the Adaptation Concepts Report as Appendix 3.
NOVEMBER 30, 2020
Interactive Story
The One Tam team released an online interactive story experience about Evolving Shorelines. It provides a fast track and engaging way to learn about the history of the marsh, how rising tides are affecting recreation and wildlife habitat, and the community collaboration to find solutions.
JULY 9, 2020
Planning Memo
To celebrate these milestones with the community, the Evolving Shorelines team hosted a Zoom virtual happy hour on Thursday, July 16, at 5:00 p.m.
NOVEMBER 6, 2019
Board of Supervisors Approves
The County of Marin Board of Supervisors approved moving forward with development of conceptual designs for the Bothin Marsh Sea Level Rise Adaptation Project, based on shared community vision and research to date. The Golden Gate National Parks Conservancy will collaborate with the Marin County Open Space District on developing and completing conceptual designs, as well as continuing community outreach.
OCTOBER 2019
Shared Vision Report
This shared vision report for Bothin Marsh reflects community feedback from hundreds of people who turned out to kayak, hike, play, and learn about the impact of climate change and sea level rise on Bothin Marsh. It is the collaborative effort of a broad coalition working to envision the future of the marsh and this section of the Mill Valley/Sausalito Multiuse Pathway.
Designing for sea level rise resilience at Bothin Marsh
MAY 6, 2026
Shoreline Adaptation Planning Community Open House
Marin County Parks staff went to a community open house on May 6 at the Mill Valley Community Center. The event was part of the City of Mill Valley’s ongoing adaptation planning efforts. Community members came to learn about current shoreline conditions, how sea levels may rise in the future, and what areas could be vulnerable.
At the event, County staff shared updates about the Bothin Marsh Evolving Shorelines Project and how it connects with the City’s broader adaptation planning. They also highlighted that the same consulting team (WRT) is helping both the City’s planning efforts and the Bothin Marsh project, which will help keep the work aligned.
The open house gave staff a chance to talk with community members, answer questions, and hear feedback. This input will help guide the project as it moves forward.
View the City of Mill Valley Shoreline Adaptation Framework.
MARCH 9, 2026
BCDC Design Review Board Presentation
Marin County Parks staff presented the Bothin Marsh Evolving Shorelines Project to the San Francisco Bay Conservation and Development Commission (BCDC) Design Review Board. The presentation provided an overview of the proposed marsh restoration and trail realignment in Mill Valley. It highlighted adaptation to sea level rise while maintaining public access and connectivity along the Bay Trail.
The Design Review Board gave feedback on marsh restoration strategies, trail design, and proposed site amenities. The goal is to slowly restore natural marsh conditions, support wildlife, and improve connections between nearby neighborhoods and the shoreline.
Planned improvements include a new trailhead, restrooms, better access and transportation options, a redesigned parking area, places to view the marsh, and updated landscaping. Marin County will continue to refine the project as design progresses, using feedback from the Board and the community.
View the BCDC presentation.
JANUARY 8, 2026
Marin Conservation League Parks and Open Space Committee Presentation
Marin County Parks staff gave an update on the Bothin Marsh Evolving Shorelines Project to the Parks and Open Space Committee of the Marin Conservation League on January 8.
Staff shared progress on the “Ring the Marsh” concept, including updates on the design and environmental review. They explained that the project aims to improve marsh habitat, help the area adapt to rising sea levels, and keep the Bay Trail open and connected for the public.
Committee members had a chance to ask questions and share their thoughts as the project continues moving forward.
OCTOBER 31–NOVEMBER 2, 2022
Meet and Greet
One Tam partners were on the Mill Valley/Sausalito Pathway in Bothin Marsh, Monday 10/31 through Wednesday 11/2/2022, 10 a.m. to 1 p.m., to answer questions as geotechnical consultants conduct subsurface investigations that will help inform efforts to preserve the marsh and protect the pathway from the impact of sea level rise.
AUGUST 20, 2022
On-site Community Workshop
An on-site community workshop took place at Tam Junction, to gather feedback on future design options for a trail connection where a proposed realigned Mill Valley/Sausalito Multiuse Pathway and Bothin Marsh Preserve could meet the junction of Shoreline Highway and Almonte Boulevard.
SUMMER 2021
Online Community Survey
The online Adaptation Concepts Survey solicited broad community input on the Conceptual Design Concepts developed for the Evolving Shorelines Project at Bothin Marsh. The survey was designed to be completed by a general audience, even those who were not familiar with the project. It included graphic representations of the project concepts with simplified descriptions of the key differences.
JUNE 8, 2021
Design Concept Options Presentation
At this online community gathering, One Tam partners – Marin County Parks and the Golden Gate National Parks Conservancy – presented three draft concepts for preserving Bothin Marsh and protecting the Mill Valley/Sausalito Multiuse Pathway. The draft concepts were informed by an evaluation of ecological and public access benefits, as well as community feedback.
OCTOBER 14, 2020
Community Conversation Zoom
During a Zoom session on October 15, One Tam partners – Marin County Parks and the Golden Gate National Parks Conservancy – presented draft concepts for the enhancement of Bothin Marsh Preserve’s tidal marsh and possible options for re-routing the Mill Valley-Sausalito Pathway. Members of the public shared comments on the design options for adapting to sea level rise. Watch a video of the Zoom session [External]
JULY 16, 2020
Virtual Happy Hour
At this informal virtual gathering, One Tam partners – Marin County Parks and the Golden Gate National Parks Conservancy – shared key findings and important considerations with the Marin community for conceptual designs that took shape in summer 2020.
NOVEMBER 25, 2018
King Tide Kayak Tour
Members of the community took part in a guided kayak tour during an exceptionally high king tide, to preview the new normal for the rising sea level at Bothin Marsh, and to explore ideas for sea level rise adaptation.
OCTOBER 17, 2019
Happy Hour Social Gathering
Proof Lab Beer Garden in Mill Valley hosted a family-friendly, happy hour social for the community to share a drink, have a bite to eat, and learn about innovative adaptive approaches being explored to address the impact of sea level rise on Bothin Marsh and the Mill Valley/Sausalito Multiuse Pathway.
OCTOBER 3–19, 2019
StoryWalk Events
Visitors of all ages enjoyed a series of reading panels installed along the Mill Valley/Sausalito Multiuse Pathway, featuring A Stone Sat Still, a book by award-winning author and illustrator Brendan Wenzel. One Tam partners - Marin County Parks and the Golden Gate National Parks Conservancy - collaborated on the StoryWalk with local libraries and Chronicle Books. A series of events along the pathway and in local libraries took place to celebrate the StoryWalk installation.
- StoryWalk Reading, Mill Valley Library, October 3
- StoryWalk Reading, Marin City Library, October 5
- StoryWalk Reading, Bothin Marsh, October 5
- Story Walk Reading, Bothin Marsh, October 19
SEPTEMBER 22, 2018
Mill Valley Shoreline Kayak Tour
Visitors joined a guided kayak tour from Bayfront Park to Coyote Creek and back, to learn about the evolution and ecology of marshes in Richardson Bay. One Tam partners – Marin County Parks and the Golden Gate National Parks Conservancy – discussed the challenges Bothin Marsh Preserve faces dues to climate change and sea level rise.
Designing for sea level rise resilience at Bothin Marsh
The much loved stretch of shoreline along Bothin Marsh Preserve provides recreation and natural beauty for visitors and residents in southern Marin. The marsh also provides habitat for unique plants and animals. The marsh is surrounded by residential and commercial development. With current sea level rise projections, this preserve will lose a significant amount of vital wetland habitat by 2030. The Mill Valley-Sausalito Multiuse Pathway will also be greatly affected by increased frequency and severity of flooding.
As One Tam partners, the Marin County Open Space District and the Golden Gate National Parks Conservancy are working with scientists to assess existing conditions and the potential future impacts from sea level rise caused by climate change. In collaboration with the Marin community, they are reviewing and developing sea-level rise adaptation designs to preserve the marsh and protect the pathway.
Objectives
- Foster ongoing an ongoing community conversation about how to preserve the marsh and protect the pathway.
- Share scientific observations about the threats of sea level rise to tidal marsh conservation.
- Develop a shared vision and collaborative designs for sea level rise adaptation.
Project Partners
Project Funding
To date, the Evolving Shorelines project has been funded primarily by Marin County Parks Measure A. The California State Coastal Conservancy, the Marin Community Foundation, and members of One Tam have also generously provided financial support.
Related Technical Documents
- Watershed sciences report [External].
- Bothin Marsh Geomorphology, Ecology, And Conservation Options [External]
Timeline
- 2016–17: Project need identified.
- January 2018: Bothin Marsh Geomorphology, Ecology, and Conservation Options research report.
- Fall 2018: Evolving Shorelines events series.
- Winter 2018: Public visioning process begins.
- Summer 2019: Bothin Marsh vision document.
- 2021:Conceptual adaptation design and recommendations.
- 2022: Tam junction connection design concepts and recommendations.