Introduction

To help people better understand how sea level rise will affect our community, the SLR Task Force has developed an interactive online map and a list of links to sources of further information. Please see below for details.

A screenshot from the interactive sea level rise map

Interactive Sea Level Rise Map

The interactive map enables residents and business owners to explore how specific levels of rising waters may affect our community. You can specify a sea level scenario, scroll through town, zooming in and out, and turn specific layers off and on to show only the information you want to see. You can also specify a street address to focus on a particular property—and its vulnerability to critical parts of Sausalito infrastructure, namely our stormwater network and wastewater treatment system. 

The SLR Scenarios layer shows the six sea level rise scenarios being used by Marin County: three levels of permanent sea level rise which are paired with a temporary sea rise due to 100 year storm surge (rising of water level primarily due to wind, from a storm that has a 1% chance of occurring a given year). These scenarios are being used for planning in the near-, middle- and long-term throughout the Bay Area, very roughly equating to 2030, 2050, and 2100. 

The State's Ocean Protection Council and the Bay Conservation and Development Commission recommend planning for 0.8 feet of SLR by 2050 and considering rates of 3.1 to 6.6 feet of SLR by the year 2100. According to the Ocean Protection Council, SLR is projected to increase the frequency of nuisance high tide flooding from a couple days per year in 2020 to nearly 20 days per year in 2050. This will cause disruptions to our daily activities such as commuting, and recreating outside. 

The software used to develop this map (ArcGIS) is very sophisticated, but you will not need to use most of the features. As you are exploring Sausalito’s sea level rise interactive map, please take note of the following:

• The Sea Level Rise scenarios indicate flooding of the ground elevation, NOT the buildings (e.g., the bottommost floor might be elevated above the ground). Despite this, the map is very useful for understanding the potential vulnerability of properties and structures.
• The layer entitled “One foot elevation contours < 15’” will only show contour lines when you are zoomed in.  If the layer name is grayed out, you need to zoom in further. Once the layer name is black, the contour lines will show up although the computations could take some time.
• This map does not address the probability or timing of SLR, which is not known precisely. See the FAQ page for more information.

Impacts to Sausalito

In Sausalito, our critical infrastructure is located close proximity to the Bay's edge. Sea level rise can lower the capacity of the existing storm infrastructure causing more flooding during events. Storm surges, which are large waves caused by storms, can also push water further inland, exacerbating the impact of floods. In addition to storm surge, in areas that have been filled in to form more land, we experience subsidence as the ground gradually sinks or settles. A 2011 study by the City of Sausalito indicates subsidence is already happening in Sausalito and will continue to in the face of sea level rise.

In 2023 the State passed Senate Bill 272 which requires local jurisdictions to have sea level rise plans that address issues like storm surge and subsidence, among others. The Bay Conservation and Development Commission (BCDC) regulates these reports and provides the guidelines on addressing sea level rise impacts to our community through their Regional Shoreline Adaptation Plan.

The City's Shoreline Adaptation Plan is ongoing through 2025 and aims to fulfil as many SB 272 requirements as possible. The Plan seeks to understand sea level rise, storm surge, subsidence and vulnerability in a Sausalito-specific context. It will help us plan for ways to protect our community while maintaining shoreline access, vital transportation and utility corridors, and enhancing marshes and beaches with nature-based solutions. We invite you to check our upcoming events listed on the Shoreline Adaptation Plan.  

Short List of Informative Resources

For learning more broadly about sea level rise in the Bay Area and California, here are the most useful resources:

• FAQ: Sea Level Rise and California: Answers to questions about sea level rise from the Scripps Institution of Oceanography.
• State of California's Sea Level Rise Guidance (2024): This provides the best available science on sea level in California. 
• SeaLevelRise.org: a portal explaining the general causes, forecast, and solutions for rising sea levels, including a specific section on California.
• Shoreline Vulnerability Index: a visual explanation of the vulnerability of different Bay Area shorelines to rising seas. Looks at criteria such as shoreline type (e.g., natural, seawall, road), shoreline height, and wave energy.
• BayWAVE Vulnerability Assessment for Sausalito: Prepared by Marin County in 2017, this document was the starting point for Sausalito’s own, more detailed vulnerability assessment efforts.
• Strategies for Managing Sea Level Rise: outlines the seven different strategies for adapting to SLR, including pros, cons, and the applicability of each to the SF Bay Area.
• Richardson Bay Resilience: a visual explanation of the impact of sea level rise on our own bay and possible adaptations to higher waters including nature-based strategies and shoreline hardening.

Additional Resources

Sea level rise is a large and complex topic! Every day, new information comes out, highlighting shoreline flooding somewhere in the world, new scientific research, and of course, creative ideas on how to adapt to rising seas. Check back here periodically for additional pointers to insightful resources.

For a deeper dive into sea level rise:

• BayWAVE Study for Marin County (2017): An initial identification of the vulnerabilities due to sea level rise for the entire county. The detail on Sausalito, mentioned above, can be found on pages labelled 164-181 (starting on page 195 of the PDF).
• San Francisco Bay Shoreline Adaptation Atlas (2019): A guide for cities, counties and other agencies to work together from a common plan, rather than randomly building projects individually that could make flooding worse for neighboring areas. Developed by the San Francisco Estuary Institute (SFEI).
• Adapting to Rising Tides (Short Report, 2020): Bay Area study of SLR vulnerability and adaptation by the San Francisco Bay Conservation and Development Commission (BCDC).
• Walling off one Coastal Area can Flood Another (2021): Scientific American article explaining how seawalls and levees traditionally used to protect one area, can backfire within a bay or estuary (such as the San Francisco Bay).
• The California coast is disappearing under the rising sea (2019): LA Times article giving examples of the difficult decisions around sea level rise adaptations such as seawalls, beach replenishment, and managed retreat. Covers issues like cost, real estate values, eminent domain, and insurance.
• SLR Reading List: Books and other resources available through the Sausalito Library.