As a series of winter storms slammed California’s coast with powerful rip currents and towering waves, part of the Santa Cruz Wharf collapsed on Monday, plunging two contractors and a city employee into the water.

The pier was one of several public wharves and piers in the state actively undergoing structural integrity upgrades.

While the coastal structures have occasionally succumbed to the ocean’s power throughout the years (including the Santa Monica Pier, once while the mayor was standing on it), the aging structures now face increasingly dynamic and unpredictable storms and often expensive and delayed upgrade projects.

“We have exposed infrastructure across the entire California coast, and it’s going to be … stressed by the impacts of climate change, whether it’s changes in storm patterns, frequency and magnitude or sea level,” said Patrick Barnard, research director for the Climate Impacts and Coastal Processes Team at the U.S. Geological Survey.

At least 10 of the state’s dozens of coastal public piers were closed for part or all of 2024 due to structural damage sustained in winter storms over the last two years. At least five more have longer-term upgrade plans to address structural issues.

In 2018, a structural analysis of San Diego’s Ocean Beach Pier found the best option to address ongoing expensive repair needs and rising sea levels was to replace the pier. In late 2023, violent winter storms walloped the pier, significantly damaging it. The city determined that continuing to repair the current pier as city officials planned for its replacement was no longer feasible. Instead, the pier will remain closed until the city completes the $8 million-plus, multiyear replacement project.

Meanwhile, the Ventura Pier and Santa Cruz County’s Capitola Wharf were damaged in early 2023 storms and reopened earlier this year. Ventura’s restoration cost more than $3 million, and Capitola’s around $8 million.

Santa Cruz initially proposed updates to the Santa Cruz Wharf in 2014, commemorating the pier’s 100th anniversary.

Although a primary engineering report for the project found that the pier was “generally in good and serviceable condition,” a secondary assessment recommended adding additional support structures to protect the pier against extreme weather.

It wasn’t until late 2020 that the city council approved a plan and environmental impact report. But then a coalition of advocates opposing the plan filed a lawsuit, arguing that the city did not find sufficient evidence to support that recreational activities on the wharf wouldn’t significantly impact the environment.

As the city litigated and revised the environmental impact report, two devastating storms in December 2023 and February 2024 — the same series that crippled San Diego’s Ocean Beach Pier — substantially damaged the wharf.

So before the city began construction on the long-term expansion and improvement project — focusing primarily on widening the pier, adding boat landings and creating more retail and commerce opportunities — it authorized $3.5 million in repairs to remedy damages from last winter’s storms. The repairs, including replacing 60 of the pier’s supporting piles, began in the fall of this year.

But it was too late. In December, another series of winter storms formed over the central Pacific and started ramming the coast with 40-foot waves.

While winter storms have been a longtime threat for California’s piers, scientists say they’re becoming even more destructive.

Recent studies have found that increasing air and water temperatures have warped ocean storm patterns worldwide, including along California’s coast. Further research shows that an intensifying low-pressure system off Alaska’s coast has become more likely to seed powerful storms and create energetic waves along the West Coast.

Climate change is also generating greater storm variability. Some piers sheltered from the typical northwestward storm now get barraged from all angles.

“In some of the recent storms in Santa Cruz, we’re seeing some of these events come a little more from the south or a little more from the west,” Barnard said. “A lot of these piers were built in these more sheltered areas … so even when those waves shift by five or 10 degrees, it can make a huge difference.”

The result for old piers sitting on the frontlines of California’s changing coasts is frequent structural assessments and repairs.

For example, the Santa Monica Pier has undergone two structural assessments since the turn of the century and a handful of smaller repairs. The latest assessment in 2019 cost hundreds of thousands of dollars.

Larger repairs often cost millions and leave a pier closed for years. If the government falls behind, the buildup of damage from extreme storms can leave officials with no choice but to tear down the whole pier. After half of the Seacliff State Beach Pier near Santa Cruz broke off into the water during a winter storm in early 2023, the state park opted to remove the pier at the advice of a structural engineering report, just a few years shy of its 100th anniversary.

Many of California’s wharves and piers are now centenarians. The state’s first wharves were built in the 1800s, and tended to be modest, private endeavors meant to facilitate shipping minerals and metals such as silver and asphaltum up and down the coast. But by the turn of the century, local governments were taking on more ambitious public projects.

Santa Monica built its nearly 1,700-foot-long pier in 1908; Santa Cruz followed suit with its own in 1914. They became a staple of coastal life, hosting fishing spots, restaurants, education centers and, in Santa Monica, an amusement park.

One hundred and ten years later, Santa Cruz had no choice but to announce that the wharf would remain closed indefinitely.

“There’s lots and lots of infrastructure across California that are at risk,” Barnard said. “There’s going to have to be hard decisions made. … There’s limited resources, and we have to think strategically about what are we going to protect?”