Jackie Krentzman is a Bay Area-based writer and editor. 

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In early September, Hurricane Marie battered Dana Point, along the Orange County coast. Twelve-foot-high waves breached the bluffs along the coast, damaging or destroying over a dozen homes.

One of those homes was Natalie Driessen’s. As the hurricane approached, her family and friends desperately tried to reinforce the seawall with sandbags.

“My entire seawall and the backyard were destroyed, and all the sand up to three feet from the house’s foundation swept away,” she says. “My foundation is still intact, but not all my neighbors were as lucky.”

Hurricane Marie may be the harbinger of what’s to come, as forecasters warn that this could be one of the most severe El Niño years in recorded history. The global climate phenomenon warms the surface waters of the tropical Pacific Ocean and changes atmospheric circulation, affecting weather around the world. While the frequency of El Niño years is not necessarily increasing due to climate change, their severity is. For most or all of California, this will likely result in an unusually wet winter.

“The chances of a strong El Niño year are about 100%,” says Daniel Swain, a University of California climate scientist. “It is as close to a certainty as it gets in the business of predicting weather and climate. This will be the most extreme El Niño event we’ve observed not just in my lifetime, but in any recorded historical period.”

Coastal cities at the highest risk

Cities along the coast, especially in the Southern half of the state, are particularly vulnerable to strong winds, sea swells, and rising sea levels that cause flooding and erosion. If these coincide with king tides — exceptionally high tides that occur several times a year — the consequences could be disastrous. El Niño has already raised local sea levels about six inches and could raise them another foot before it ends — essentially double the amount caused by climate change over the last century.

“And when that happens, sometimes coastal bluffs will get eroded and collapse a bit, and there might be homes involved, or train tracks and other infrastructure damaged,” says Dr. Fred Ralph, a meteorologist with the UC San Diego Scripps Institution of Oceanography.

Given this level of certainty and potential havoc, Gov. Gavin Newsom this September declared a state of emergency for this coming winter. But many California cities have been preparing for even longer.

Take Dana Point. This city of 33,000 is not only used to high surf — it revels in it. Some consider it the epicenter of the surfing industry, as several legendary surfing companies got their start here. But the surf that residents have experienced this year has been devastating.

“El Niño has already hit us with tropical swells, hurricane remnants, humidity and warm water, and over the last couple of months we’ve seen the results: strong surf, beach erosion, and damage to homes,” says City Manager Kelly Reenders. “As we move into winter, the focus shifts to king tides and storms coming in from the North Pacific. We know from past El Niños that those storms can cause more erosion, and this year we have less sand to buffer them.” 

Fortunately, Dana Point has been preparing for a season like this for years. The city has partnered with local agencies, cleared storm drains, launched a sandbag program for residents, and removed debris to reduce the impact of landslides and soil sloughing. The city even bought a land lot near the Pacific Coast Highway to pre-stage equipment and facilitate a quick response when the storms come. Dana Point is also participating in informational briefings, holding preparation meetings with neighboring cities and the sheriff’s department, and educating the community on how to prepare for severe weather.

“It’s important to be proactive,” Reenders says. “Better to spend some extra money on crews and personnel now so when the emergency comes, we will be ready.”

Swain urges other coastal and flood-prone cities — even those in Northern California — to follow suit. For starters, he recommends penciling in dates of king tides.

“If a storm comes at the same time, we know that these areas are going to flood,” he says. “What is the plan for preemptively shutting down roadways that are prone to coastal flooding? We probably shouldn’t just be letting people drive through it and then act when they stall their cars.”

San Rafael in Marin County already has a plan. The city is at great risk, as king tides regularly swamp city streets. City Manager Paul Navazio is concerned that a storm during a king tide will overwhelm the city’s drainage system and severely impact its low-lying areas — home to a large concentration of people and businesses.

To make matters worse, the king tides along the Marin County coastline this year coincide with Thanksgiving and Christmas. If that coincides with a storm, the streets could be even more dangerous. The city is telling residents to consider leaving the area for the holidays if feasible and refrain from hosting parties. It is also identifying parking structures where people can temporarily relocate their vehicles.

“We can’t fully prevent the impact, but we can triage to minimize it,” says Navazio, who takes consolation in knowing exactly when the king tides will arrive. “What’s unique about this situation [unlike an earthquake] is the fact that we are able to predict what could happen and when. That, at least, gives us a small advantage.”

Inland cities must prepare too

Until about 150 years ago, Tulare Lake in the Central Valley was one of the largest freshwater lakes in the West. Farmers moved in to take advantage of the fertile soil and began diverting the water for irrigation. In 1914, the city of Corcoran was incorporated in the dried-out lakebed.

Over the decades, the atmospheric rivers that battered California stayed well north of Corcoran. But in March 2023, a storm swept through the region that, coupled with an unusually large melting snowpack, broke a levee and revived the long-dormant lake. Fortunately, the city was protected by other levees, and the damage was minimal, says City Manager Greg Gatzka.

Gatzka isn’t too worried that a storm like that will threaten Corcoran this year. “We have never seen a storm here of this magnitude in my lifetime,” he says. “From what experts have told me, this is like a 1 in a 500-year event.”

Corcoran and other local agencies have nevertheless planned for the possibility. The Cross Creek Flood Control District retrofitted and raised the Corcoran levee. And agencies upstream in Fresno and Tulare counties created new canals and diversions for runoff, easing flooding danger.

“The learning lessons and the proactive planning and maintenance that occurred after the 2023 floods has put us in a good position to avoid worst-case scenarios of potential flooding for the city of Corcoran,” Gatzka says.

Watsonville, in southern Santa Cruz County, also experienced flooding in 2023. That January, several feet of water flooded neighborhoods and caused substantial damage after the Corralitos Creek breached during a storm. Then, during a March storm, the neighboring community of Pajaro flooded when the Pajaro River levee failed.

“The levee system was built in the 60s and is substandard in terms of its ability to protect our community,” says Watsonville City Manager Tamara Vides. “We cannot rely on it to hold back the water.”

The city is bracing for strong weather events this winter as the newly formed Pajaro River Flood Management Agency moves forward with a long-term levee-repair project. The city is also coordinating with the county’s emergency operations center in case it needs to respond immediately.

But Vides says one of the most important steps is preparing and communicating with residents. “You cannot wait until there are five inches of rain,” she explains. “Everybody’s talking about El Niño, and that we will see a lot of water come down. So, we are asking our residents, ‘How are you prepared?’”

In October, Watsonville set up a station where residents could pick up free sandbags to shore up their properties. The city created videos that demonstrate how to properly sandbag garages and porches. It is also preparing its public works, police, and fire staff, along with community partners and other government agencies, by training them in FEMA Emergency Operations Center activation drills.

What can cities do?

With El Niño on the horizon, cities can take several steps to minimize the impact and damage. San Rafael, for example, allocated $500,000 from its General Fund to acquire temporary pumps, generators, sandbags, and emergency equipment. Emergency declarations can unlock additional emergency funding. Cities can also encourage residents to sign up for emergency alerts, plan evacuation routes, move valuables out of low-lying areas, stock emergency supplies, use city-provided sandbags, and avoid driving through floodwaters.

Although repairing and reinforcing much of the infrastructure that protects cities from flooding is often a multiyear project involving multiple government entities, cities can take some smaller, related actions now. Alameda, for example, is conducting storm drain maintenance and working to protect its shoreline from flooding. Cities can also prioritize removing debris and sediment from known flood hotspots and underpasses. Other proactive actions include:

• Pre-positioning pumps, sandbags, and barriers.
• Moving portable pumps, temporary flood barriers, sandbags, and backup generators to vulnerable neighborhoods before roads become impassable.
• Inspecting critical infrastructure.
• Checking drainage channels, retaining walls, bridges, and other water conveyance systems, along with pumps, backup power, and emergency generators.
• Preparing roads and evacuation routes.
• Staging equipment near flood zones now, so they are easily accessible when needed.
• Identifying roads likely to flood, staging barricades, inspecting alternate routes, preparing detours, and arranging rapid road closures — ideally before dangerous conditions develop.

Perhaps most importantly, cities should remember that storms and flooding know no boundaries. Cities should partner with other cities, public agencies, and nonprofits to prepare.

“This year will be a test case for cities,” says climate scientist Daniel Swain. “In recent years we’ve been so concerned about fires and drought, understandably, that sometimes we forget that some of the strongest evidence of increasing weather hazard risk in California is from is extreme rainfall and flooding.”