After Oroville, a flood policy for both deluge and drought

The Yolo Causeway, heading west toward Davis, is surrounded by water in the Yolo Bypass. Creating more such floodplains in the San Joaquin Valley might recharge drought-shriveled aquifers while allowing less reliance on dams.
The Yolo Causeway, heading west toward Davis, is surrounded by water in the Yolo Bypass. Creating more such floodplains in the San Joaquin Valley might recharge drought-shriveled aquifers while allowing less reliance on dams. rpench@sacbee.com

One hundred fifty-six years ago, on the night before Christmas, a wave of epic storms rushed in from the Pacific Ocean, pummeling Gold Rush California with great sheets of violent rain. For more than 40 days and 40 nights, the rivers of the Sierra Nevada raged, swollen with melted snow. Mining camps, bridges and saloons were swept away like toys.

Levees crumbled. Thousands died. An entire Chinese mining community perished in the Yuba River. The Central Valley became an inland sea, submerging farms, villages and whole herds of livestock. In the Sacramento Valley, telegraph poles stood under water 30 feet deep.

In Sacramento, Gov. Leland Stanford had to paddle from his mansion to the Capitol in a rowboat to be inaugurated; by the time he paddled home, the water was so high, he had to re-enter through a window on the second floor. The Legislature fled to San Francisco. The state was bankrupt six months later when they returned.

If there is a single recurrent theme in the annals of California, it is nature. The flood of 1861-62 was the worst in the state’s recorded history.

In less-recorded history, over thousands of years, monstrous storms have hit here every century or two, says UC Berkeley paleoclimatologist B. Lynn Ingram, who has written extensively, and beautifully, on the famous 19th century flood and extreme weather before it.

Epic dry spells punctuated with bigger storms – that is about to become California’s new normal. Thinking beyond dams might help us adapt on both fronts.

“This is something we should prepare for, just as we do for big earthquakes,” she told a member of The Sacramento Bee editorial board last week.

On average, Ingram says, the West is becoming inexorably drier. But in the meantime, climate change has made storms more severe and made the precipitation we do get likelier to fall as rain, rather than snow. A 2011 U.S. Geological Survey study modeled on the 1861 storms found that if they hit today, they would overwhelm levees and dams.

In the wake of the Oroville Dam near-hit, state lawmakers have been scrambling for short- and longer-term ways to prepare for the next storm-borne disaster; Gov. Jerry Brown has called for nearly $450 million in state spending to shore up flood control.

But climate experts say flood is only half the picture. Long-term drought punctuated with deluge is about to become California’s new normal, thanks to the way global warming has amplified regular climate variations.

So while they’re at it, state officials should ask whether now might be the time to join nature, rather than just trying to beat it.

Sure, fix the dams and levees that have shielded us from winter rains so far. But also find ways to make natural flood patterns work for us.

A 2,000-page report issued in November by the California Department of Water Resources details the efforts California has made over the generations, and the sorry state of California’s levees in the 27,200-square-mile Sacramento River hydrologic region and the 15,300-square-mile San Joaquin River region.

In language far wonkier than Ingram’s writings, it sums up the situation: Existing levees offer little real protection for $600 billion in assets and more than 7 million Californians who depend on them.

Brown has placed the cost of improving the state’s water infrastructure at a daunting $52 billion. His solutions include the $15 billion tunnels, which would more efficiently transport water south from three intakes along the main Sacramento River channel in the Delta. The tunnels would lessen the need to rely on some Delta levees. But the decision about whether to proceed is pending.

It rests partly with state and federal agencies, which must assess the environmental consequences, and on whether direct beneficiaries in Santa Clara and Alameda counties, San Joaquin Valley and Kern County growers, and the Metropolitan Water District of Southern California are willing to pay.

Perhaps Californians will spend the billions required to bore 30-mile-long tunnels and fortify the thousands of miles of privately and publicly maintained levees. Perhaps President Donald Trump’s infrastructure promises will come through, though we have our doubts.

That’s why current planning should include a fresh look at the way we manage flood and drought generally in California. Concrete alone won’t work forever. Where possible, maybe working with, rather than against nature, is the smarter route.

For example, yet another report – issued last week by the Public Policy Institute of California – found that some of the most severely drought-depleted groundwater basins in the San Joaquin Valley are also on floodplains that become overwhelmed in rainy years.

Could the state kill two birds with one stone by spending judiciously on flood easements in places such as the undeveloped farmland east of Modesto, or in south Sacramento County, paying landowners to let low-lying farmland flood naturally so that drought-shriveled aquifers can recharge?

Would flatter levees with wider setbacks, such the big levee between West Sacramento and the Yolo Bypass, give more running room to floodwaters – and put less pressure, not only on infrastructure, but also on fish and wildlife?

Such solutions, less about what we do than what we don’t do, may not offer politicians the publicity of a ribbon-cutting at a new dam or an improved spillway. But given California’s other historic theme – development – a good time to try them would be now.

Making flood policy about drought, too, could deepen the legacy Brown is leaving the state on climate, and help Californians keep history from repeating itself.