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Storms Could Signify Changing Climate In California

 As spring arrives in California, scientists and public officials are taking stock of a stormy winter that eased the state’s five-year drought but exposed the vulnerability to age and climate change of the Golden State’s dams, levees, and bridges.

 

Calamity was narrowly avoided in February north of Sacramento when the 770-foot high Oroville Dam, the nation’s tallest, filled and water was diverted into an emergency spillway because the main spillway was damaged. Nearly 200,000 people downstream from the dam were evacuated at the height of the crisis.

 

There were other danger points in California’s wettest winter of modern times. Overall, flooding caused $1 billion in damage, according to state officials. More than 14,000 San Jose residents were evacuated and hundreds lost their homes when a debris-clogged creek overflowed. Huge chunks of levees were ripped loose along the Sacramento Delta. Near Big Sur, cracks in the Pfeifer Canyon Bridge forced closure of the scenic Pacific Coast highway. The bridge will be demolished and the highway closed for up to a year.

 

California is no stranger to abnormal weather cycles, but some scientists say conditions are becoming worse. “We’re seeing...emergence of a climate characterized by greater frequency of warm dry conditions punctuated by extremely wet conditions,” said Noah Diffenbaugh, a climate expert at the Stanford Woods Institute for the Environment.

 

A new climate plus old dams is a risky combination. As New York Times columnist Timothy Egan puts it, “yesterday’s dams are trying to hold back tomorrow’s climate.” Nor is it just the dams that are outdated. Much of U.S. infrastructure was “built for the past,” says Juliet Christian-Smith, a climate scientist with the Union of Concerned Scientists.

 

By 2025, according to the American Society of Civil Engineers, 70 per cent of U.S. dams will be 50 years old. Oroville, completed in 1968, is already that age. There are 17 high-risk dams in California with the riskiest probably a dam at Lake Isabella on the Kern River, built by the U.S. Army Corps of Engineers to protect Bakersfield from flooding. When construction was completed in 1953, an earthquake fault beneath the dam was believed to be dormant but has since shown signs of activity.

 

Despite such concerns, California officials are rejoicing at the size of this year’s snowpack in the Sierra, which provides a third of California’s drinking water. Thanks to winter storms, the snowpack is 185 percent of normal. The hope is that spring temperatures in the Sierra remain cold to avoid flooding from fast-melting snow and to keep snow available in late summer, when it rarely rains in California.

 

Gov. Jerry Brown (D) is waiting until peak snowpack in April to decide whether to declare that California has emerged from the drought. In the meantime the State Water Resources Control Board has extended conservation regulations prohibiting wasteful practices such as watering lawns after rains. A few drought-stricken localities still ban all lawn watering.

 

According to the U.S. Drought Monitor, 70 percent of California is now free of drought. Moderate to severe drought persists in 9 percent of the state with 10.2 million residents. “Abnormally dry” conditions exist in 21 percent of California.

 

Water storage levels in California reservoirs are well above normal for March, but vary throughout the state. Lake Oroville, for instance, is at 115 percent of normal. Lake Cachuma, which provides water for Santa Barbara and several other central coast communities, is only 54 percent of normal.

 

In Sacramento, the winter is gone but not forgotten. Gov. Brown has proposed a $437 million plan to speed flood control efforts in northern California and improve the readiness of the state’s emergency operations. But Brown, notoriously stingy in spending public money, balks at multi-billion bond proposals put forward by key Democratic legislators that could be used to build new dams, improve existing ones or replenish storm water recycling. Brown favors pay-as-you-go financing, and calls bonds the equivalent of a tax. A two-thirds vote in the legislature and the governor’s signature are required to put a bond measure on the ballot.

 

New bond measures may not be necessary if the governor and the legislature agree on how to spend $11.8 billion in previously approved natural resources bonds. Brown has asked legislators to tap this money to pay for his flood control proposal. Beyond this stop-gap effort, however, there is no consensus on how California should focus its water priorities. Agriculture, which uses 80 percent of California’s water, has long sought increased reservoir storage. Environmental concerns have blocked construction of new dams since the mid-1970s, and the near-calamity at Oroville Dam this year did not improve prospects for additional dams. When Oroville was re-licensed in 2005, three environmental groups warned of the inadequacy of the earthen spillway, which they wanted lined with concrete. Their warnings were ignored.

 

Dams are not the only issue. Jay Lund, who heads the Center for Watershed Sciences at the University of California-Davis, said that even when dams were big enough to handle the water many downstream levees were not. Dead trees and debris clogged Coyote Creek near San Jose and caused the flooding there. Sediment clogs many smaller reservoirs.

 

Despite the winter rains, California is still shadowed by the legacy of drought. Satellite images show depleted ground water levels, especially in the San Joaquin Valley, which provides much of America’s fresh produce. It takes more than a single season to replenish underwater aquifers.

 

Nonetheless, some environmentalists see sustainable groundwater enriched by improved storm water capture as a long-term solution. “We’ve focused the vast majority of our effort and funding on surface water systems or above-ground reservoirs, while essentially ignoring the storage available beneath our feet,” says scientist Christian-Smith.

 

But in a state as vast as California, there’s no single remedy for water needs. Orange County and Silicon Valley recycle waste water for irrigation with an eventual goal of using this water for drinking and bathing. In Santa Barbara a rebuilt desalination plant is near completion.

 

As Californians ponder their choices, they wonder if this winter’s storms were an aberration or a window to the future. The track record of past prediction suggests that the answer to this question is unknowable.

 

In 2016, for instance, climatologists said an El Nino condition in which a warm ocean current develops along the coast of Ecuador and Peru, would lead to heavy rainfall in Southern California. One eminent climatologist, quoted by this columnist and many others, predicted a “Godzilla” of storms. Instead, barely four inches of rain fell during the entire winter in much of the region. This year was supposed to be a dry La Nina year.  It produced record rainfall in Los Angeles and many other parts of Southern California.

 

But viewed through a long lens, these records are trivial. In geological terms the whole of human history in the West is a flyspeck. Tree-ring studies going back hundreds of years show decades of drought and long periods of wet weather in California.

 

Even comparatively recent times had wet winters that dwarf 2017.  In December 1861, rain began falling in much of the West in mid-month and continued for 43 days through January. What came to be called the Great California Flood created an inland lake 300 miles long and 20 miles wide in the San Joaquin Valley. But California then was home to only 380,000 people, a tenth of today’s population, and there are no reliable records of rainfall totals or casualties. Because the event occurred during the Civil War, it’s little more than a footnote in most history books.

 

Going forward, Californians can’t be sure if they’re on the brink of devastating climate change. All they can do is hope for the best while continuing to prepare for momentous rainy seasons and protracted dry spells.