It’s raining in California. Again. A storm system hitting north and central California on Monday and Tuesday will deliver two to three inches of rain to the Central Valley, and up to 10 inches of rain to the mountains, said Eric Kurth, a meteorologist with the National Weather Service in Sacramento. The service has issued a flood warning through Wednesday across most of the Sacramento River Valley and the surrounding areas.
Oroville Dam’s badly damaged main spillway is still deteriorating from an onslaught of fast-paced water, but state officials insist that it is “stable” as they make repairs. State officials expected the concrete main spillway to erode last week when they opened its gates, betting that it was a safer option than the dam’s little-used emergency spillway.
You hear this every time there’s a drought or deluge in California: “Why haven’t they built more dams?” Truth is, they’ve built a bunch. And they’re about done with it. Tally them up. There are more than 1,400 dams in the state. At least 1,000 are major and 55 can hold 100,000 acre-feet or more of water. One acre-foot is enough to supply two average households for a year. There are 36 reservoirs that can contain at least 200,000 acre-feet. Eleven can hold 1 million or more.
The early settlers snatched up the rich, loamy land along the Feather River to grow grapes and orchards. Edward Mathews, an Irishman who fled the potato famine, was peddling vegetables and didn’t have the cash for that kind of soil. During heavy rains, the Yuba River would flow so hard into the Feather at Marysville, it pushed the Feather back north into Jack Slough, named for a freed slave who in 1861 sold Mathews 200 acres of its poor red soil.
Bill Croyle stood in front of an aerial photo of Lake Oroville and swept his hand across the top of the emergency spillway that was helping drain water out of the brimming reservoir. “Solid rock. All this is rock,” Croyle, acting director of the Department of Water Resources, said with an air of confidence at the Feb. 11 briefing. The flows over the concrete lip of the unpaved spillway were tiny compared with what it was designed to handle. Oroville’s first-ever emergency spill was going smoothly.
The dam burst on a warm afternoon, unleashing nearly 300 million gallons of muddy water on a Los Angeles neighborhood. Five people died and dozens of homes were swept off their foundations and destroyed. In the aftermath of the 1963 Baldwin Hills Dam catastrophe, the state strengthened inspection regulations, helping establish California as a modern leader in dam safety.
How did a giant, gaping hole tear through the massive Oroville Dam’s main concrete spillway last week, setting in motion the chain of events that could have led to one of America’s deadliest dam failures? Dam experts around the country are focusing on a leading suspect: Tiny bubbles.The prospect is simple, yet terrifying and has been the culprit in a number of near disasters at dams across the globe since engineers discovered it about 50 years ago.
No disaster is entirely natural in our re-engineered state and valley. Owing to our hubris, we humans have a direct hand in them all. We have built cities on earthquake faults, balanced mansions on hillsides that burn in one season and slide into the ocean in the next, and moor boats in marinas where tsunamis are known to strike. Having dammed almost all major rivers in California and many tributaries and creeks, we have constructed entire cities in what a century or 150 years ago was swamp, and made islands of rocks piled on peat.
California is not the only place in the West confronting startling amounts of rain and snow. Drought conditions have declined substantially across the region in recent weeks, with heavy storms replenishing reservoirs and piling fresh powder on ski resorts. Yet there is one place where the precipitation has been particularly welcome and could be transformative: the Colorado River basin, which provides water to nearly 40 million people across seven states.
Cleanup was beginning across Southern California on Saturday after a storm that forecasters billed as the most powerful in years caused flooding on multiple freeways, triggered dramatic mudslides and downed hundreds of trees and power lines. The storm was moving out Saturday morning after dumping record rain in some areas and leaving havoc in its wake. Thousands of Los Angeles County residents remained without power early Saturday, while road crews scrambled to repair sinkholes throughout the area, including one in Studio City that swallowed two vehicles Friday night. No one was injured in the incident.
