Adaptation ideas for sea level rise in San Rafael recall solutions from the past

THERE IS STILL NO BLUEPRINT for a shovel-ready plan, but there is a new feasibility study for flood protections in San Rafael. With the fastest long-term alternative projected to take 10 to 15 years to complete, the study leads with a list of immediate actions that can temporarily buy time.

The “Community Informed Technical Feasibility Study” released Monday analyzes three infrastructural designs that would protect the city from flooding caused by sea level rise for the next 45 to 75 years – build barrier walls, insert a flood gate in the Canal, or raise the land with new buildings and parks at the water’s edge. Similar recommendations have appeared in feasibility studies going back to the 1980s, but this time the “city with a mission” is under pressure from a state deadline. 

The study comes at a time when all Bay Area and coastal cities are pushing to generate shoreline adaptation plans by 2034. They must submit them to the Bay Conservation and Development Commission, a state regulatory agency responsible for the San Francisco Bay and shoreline. Under Senate Bill 272, local governments whose plans are approved will be prioritized for state grants. 

Funded with $762,000 from the California State Coastal Conservancy and the Marin Community Foundation, the study evaluates the alternatives based on flood protection, including implementation time, housing, land access, permitting, neighborhood improvements, ecological impacts and costs. Ballpark price tags range from $719 million to nearly $2 billion. 

“There have been other studies before this that have underscored how expensive this is, but that is one of the main challenges that we have here,” said Kate Hagemann, San Rafael’s climate resilience director in Monday’s public presentation. “Any project getting external funding from state or federal sources will likely also still need a local contribution. Sometimes that’s 25% or 35%.” 

 A “no action” alternative illustrates the damages to highways, buildings and livelihoods to expect when East San Rafael is knee-deep by 2050. The study begins with a list of initial actions that could be done right away. 

The geological problem

What makes San Rafael a unique problem for engineers is that its shorefront was artificially extended a mile into a tidal marsh in the 1950s. The land retained its memory. During epic storms and king tides, the densely populated Canal peninsula floods because that is where the rain and the sea collide, just like a tidal marsh.

All rain from the downtown watershed flows in and under the peninsula and is captured by a system of pumps that throw the fresh water into San Pablo Bay. Pumps are the life support system for the Canal district.

But over time, the district has subsided into a bowl shape. Its central exit roads dip to just 3 feet above sea level. Daily high tides reach 4 to 6 feet, just below the homemade sea walls that landowners may or may not maintain. As the lowest lying area of San Rafael, the Canal has always been the most severely impacted by seasonal storms and sea level rise. Sometimes water pools upland into the downtown.

News clips from 1958 show people canoeing down Lincoln Avenue after a winter storm. One of the most catastrophic flooding events happened in 1982, when some of the pumps failed.

In early January of this year, king tides and storm surge peaked above 8 feet and topped the edge of the Canal, flooding the bowl with Bay water, submerging vehicles and leaving many of its rental residents islanded.

The Bay mud used to infill the Canal district consists of soft, water-saturated materials, making it susceptible to liquefaction during an earthquake. That risk includes destabilizing the coastal barriers that exist today, as well as soft story failure in many of the multifamily buildings in the district, according to Andy Sternad with Waggonner & Ball, the engineering firm that was commissioned to do the new study.

The new study includes a list of nature-based solutions that can be applied with all options. They include planting native vegetation like eelgrass amid rocky nearshore reefs, placing reef balls and oyster blocks to encourage plant life and crustations, adding precast tide pools and removing debris and derelict structures.

By rebuilding some of the physical profile of a tidal marsh along the Bay, it is possible to replace some ancient flood protections, with future maintenance and operating costs handed over to Mother Nature.

In 1992, the U.S. Army Corps of Engineers considered the feasibility of two of the same solutions presented in the new study — floodwalls and a tidal gate. Thirty-four years ago, a floodwall along the south edge of the Canal was found to be the most economically efficient choice at $24.7 million. Adjusted for inflation that would be equivalent to about $57 million today. 

“The corps recommendation was not done, as I recall, because the residents along the creek did not want their views impacted by a wall, which is what the corps recommended,” said Barbara Salzman, president of the Marin Audubon Society. She was actively involved in protecting wetlands in Marin County at that time. 

Left: An artist’s rendering shows a tide barrier (behind dock) at the mouth of the Canal proposed in a sea level adaptation feasibility study by the U.S. Corps of Engineers in 1992 for San Rafael, Calif. Right: A 1992 technical drawing of an offshore flood wall shows how water can be used to balance pressure on both sides. Similar proposals appear in a 2025 sea level adaptation feasibility study published in Oct. 2025. (USACE via Bay City News)

Aside from this, the study suggests three alternative approaches:

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Alternative 1 involves building living walls around the Canal, 12 feet above sea level, and guarding the edge all the way under U.S. Highway 101 and upland to Mahon Creek and a few other wet spots. The bayfront levee would be raised to about 14 feet. Additional elevations would need to happen to all the edges around 2070 to make it through the century. On the north side of the Canal, individual structures and access roads would need to be raised over time. In this scenario, there is a potential five-year gap in protection, leaving the community at risk during the length of the construction. 

According to Sternad, this option is meant to keep as many existing buildings and housing units in place as possible. 

Technical drawings of flood wall designs appeared in the 1992 Army Corps study, along with an artist’s rendering of how they might look in front of the homes in the Newport neighborhood at the tip of the Canal. 

“Some of the homeowners objected for aesthetic reasons,” said former San Rafael Fire Commissioner Larry Luckham, citing a lack of funding and will for the inaction. “There were also a number of technical obstacles that I raised, including the fact that some of the apartment buildings, like 400 Canal, project out over the water complicating the idea of having a raised barrier at the top of the bank.”

The new study, like the one in 1992, places some walls offshore, around those few buildings that have their legs in the water. A little low water would be allowed to flow behind them through an adjustable gate to keep them upright with fair pressure on both sides. Unlike the 1992 design, the new one adds sculptural features to the walls that encourage the faster establishment of native plants and crustations.

The condition of the southern edge of the San Rafael Canal has been the same for decades. 

“There is a large area, including Highway 580, where the land is lower than the high tides,” said Hagemann. “It’s not flooding every day because individual owners, yards, gardens, businesses are blocking the water,” she said. “If we have an owner that digs a trench on the side of their building, which has happened, the Bay starts to flow in. That’s on private property. “ 

“There are no existing federally constructed flood control facilities in the Canal area,” said a 1989 Corps of Engineers study. “Existing flood control levees, floodwalls, storm sewers and pump stations are constructed by local public and private interests in a piecemeal manner over a period of decades.”  

On Monday, Hagemann said the city does not have public staff that maintains or inspects the privately owned shoreline. 

“Someone’s private driveway would be their own responsibility,” she said in an email. “Any town could get together and decide to change those roles and responsibilities, but at the moment that is the division of responsibility (and funding) that we have.” 

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Alternative 2 – Flood gate

Estimates: 10 to 15 years to build; cost $ 557 million; protection until 2100

Alternative 2 would place a 16-foot navigable flood control gate near the mouth of the Canal, with pumps on the backside to throw the stormwater over to the Bay when it pours. 

Bayfront and Canal edges would still need to be raised to 14 feet, with additional elevations by 2070. The design life of the gate itself could last up to 2100. Maintenance and operation would require the creation of a new city department, which factors another $7.9 million a year. 

The tidal gate option is seen as offering the highest level of flood protection in the shortest amount of time using the least about of land.

“The shortest option is the Canal gate, which makes sense,” said Sternad. “Although we’re not necessarily dealing with all the shoreline behind it.”

Back in 1992, the Army Corps thought the tidal gate would be closed only a few times a year, when king tides coincided with exceptional meteorological conditions. Today, with climate science predicting the rate of sea level rise increasing over time, the tidal gate would need to close more frequently, potentially compromising the ability to permit this alternative as the least environmentally damaging option.

“It would close one to three times monthly with one foot sea level rise by 2050 and one time weekly with a three-foot sea-level rise by 2100,” the new study said. 

The more often the creek shed is cut off from the sea, the more damage it would cause to upstream ecosystems and environmental health.

“While intuitively it may seem like a simple solution to close the valve, there’s a lot of complexity introduced in operating that gate,” said Sternad. “If the gate needs to close more frequently and ultimately permanently, there may be even more mitigation costs to address the impacts within San Rafael Creek.”

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Alternative 3 – Raise the land

Estimates: 20 to 40 years to build; cost $1.9 billion; protection until 2100

Alternative 3 involves acquisition, demolition, fill and redevelopment of the blocks along the waterfront. It could be done through private-public partnerships, or with the kind of ordinance used in San Mateo County that permits developers to elevate the land along the shore. 

This option would localize redevelopment to make space for a levee, new public trail and parks, possible new housing, a vegetated shoreline and possibly accommodate a new pedestrian bridge.

Due to a long construction period, this scenario comes with an estimated 20-year potential gap in flood protection, although it does provide the longest period of protection after completion.

Upfront costs would be high. The study estimate does not count the additional investment to rebuild. However, this option does provide the potential to recoup costs through land redevelopment. 

The social cost is also high. It would displace the occupants of 86 Canal shoreline buildings and likely require permanent relocation of some residents in efforts led by the city and within city limits.

The number of private landowners would pose a significant hurdle to this process, as acquisition would be voluntary, and protection from the sea depends on 100% participation.

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Initial actions

The Canal is home to a vulnerable Hispanic community of over 10,000 residents. They came to a sanctuary state and found themselves in danger of displacement. 

A community engagement element was included in the research done for the study. According to Hagemann, over the three-year grant period, a coalition of nonprofits worked with the city to hold 145 events on sea level rise, reaching more than 5,000 people living or working in the Canal.

A group of Canal residents called the Sea Level Rise Working Group released a statement this month urging decision-makers to move faster on a flooding solution.

“[We call] for immediate, low-cost actions to reduce flood risk, including maintenance and upgrades to drainage and pump systems, improved stormwater management and emergency preparedness measures,” the statement said.

With the fastest infrastructural solution a decade away, the study prioritizes a list of immediate actions; some needed to happen yesterday. 

“Initial actions to modify the Canal and Bayfront shorelines would buy time to plan and build the longer-term solutions,” the study said.

Initial actions include identifying the weak points in the riprap levees and homemade sea walls that face the Canal and replacing them with better materials to raise the edge to 8 feet. Raising the edge of the Canal is a component of all the long-term options, so this would be a move in the right direction.

Another initial action is for the city to continue to restore wave-absorbing tidal marshes, like the Tiscornia Marsh at the tip of the Canal peninsula. Planting oyster beds just beyond the shore will also help tone down the tides that erode the shore.

The city can also start to find ways for the private property at the water’s edge to become public property. 

“Infrastructure that serves a public safety function is most reliably maintained when subject to public oversight in the public domain,” the study said.

For all the initial and long-term alternatives, the dozen pump stations positioned around the Canal, bayfront and northern banks need to be maintained and upgraded. As measures are put in place to hold back the sea, the footprint of the forced drainage area is likely to expand and, as land subsides, the demand to move surface water will grow.

Final initial actions include further investment in multifamily housing on higher ground to support the incremental reconstruction of low-lying areas and the proactive elevation of critical infrastructure, like Fire Station 54, to ensure emergency response in the event of stormwater flooding and/or catastrophic overtopping.

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Tipping point

The impact of sea level rise on the land is like the impact of a king tide, except sea level rise is permanent.  

This month’s storms brought a combination of king tides and storm surge, with tides measuring 8.7 feet.

Sternad ended his presentation Monday with a visual model that projected the impact of sea level rise on a map of the Canal.

“As we approach that tipping point around 9 feet, you see the impacts grow,” Sternad said. “This is not a future condition. They just become more likely over time. These higher water levels have a statistical probability of being observed any year.”

According to a recent study by the California Institute of Technology, the land in San Rafael and other shoreline Bay Area cities is subsiding at a steady rate of more than 0.4 inches per year. Combined with tide elevation estimates, local sea levels could permanently rise more than 17 inches by 2050.

By pushing permanent changes back decades, the city is at risk of being complicit in an environmental injustice. Hagemann underlined the city’s efforts to prepare the community for change.

“Unfortunately, those kinds of projects take years to decades to build, and we have a risk right now,” said Hagemann. The community has asked the City Council to take action now to address those risks, she said, and the city’s efforts have coalesced around short-term priorities, but the long view must not be lost. 

 “So that we’re not building new bridges that flood just after they’re constructed.”