By Patrick Ruckert
February 13, 2017
As of this morning, about 200,000 people are continuing to be evacuated south of the Oroville Dam, which is still threatening to unleash a three story wall of water if the emergency spillway collapses.
Over the past few weeks, near record amounts of rain and snow have not only ended the drought in more than one-half of the states, filled the reservoirs, and caused some flooding, but now with the damaged spillway at the Oroville Dam, threatens a major catastrophe.
Oroville dam at 770 feet in height, is the highest dam in the United States, and its reservoir is the second largest in California. Located about 60 miles north of Sacramento on the Feather River, the dam and lake is a central piece of California’s State Water Project, supplying water for the state’s Central Valley agricultural heartland and Southern California.
Last Tuesday a hole in the dams main spillway was discovered, which as the flow of water continued, continued to grow. Photos taken after the spillway was closed showed serious damage, which now is estimated to be as large as a football field and about 50 feet deep.
As water continued to pour into the reservoir behind the dam the operators had no choice but to reopen the main spillway to prevent the reservoir from topping the dam, causing untold damage to the entire structure. But, the reservoir kept rising and by Saturday the emergency spillway designed for just such an emergency began sending water over the earthen front-side of the dam. The emergency spillway was rated to handle 250,000 cubic feet per second flow, but it began to show weakness Sunday after flows peaked at only 2,600 cubic feet per second.
That was when the evacuation order was issued.
An article in the San Jose Mercury News on February 12 by Paul Rogers, “Oroville Dam: Feds and state officials ignored warnings 12 years ago,” claims that, “More than a decade ago, federal and state officials and some of California’s largest water agencies rejected concerns that the massive earthen spillway at Oroville Dam — at risk of collapse Sunday night and prompting the evacuation of 130,000 people — could erode during heavy winter rains and cause a catastrophe.”
As Rogers reports, “Three environmental groups — the Friends of the River, the Sierra Club and the South Yuba Citizens League — filed a motion with the federal government on Oct. 17, 2005, as part of Oroville Dam’s relicensing process, urging federal officials to require that the dam’s emergency spillway be armored with concrete, rather than remain as an earthen hillside.”
“The Bush administration rejected that request, however, after the state Department of Water Resources, and the water agencies that would likely have had to pay the bill for the upgrades said they were unnecessary. Those agencies included the Metropolitan Water District of Southern California, which provides water to 19 million people in Los Angeles, San Diego and other areas, and the State Water Contractors, an association of 27 agencies that buy water from the state of California through the State Water Project.
“Federal officials at the time said that the emergency spillway was designed to handle 350,000 cubic feet per second and the concerns were overblown.
“On Sunday, with flows of only 6,000 to 12,000 cubic feet per second — water only a foot or two deep and less than 5 percent of the rate that FERC said was safe — erosion at the emergency spillway became so severe that officials from the State Department of Water Resources ordered the evacuation of more than 130,000 people. The fear was that the erosion could undercut the 1,730-foot long concrete lip along the top of the emergency spillway, allowing billions of gallons of water to pour down the hillside toward Oroville and other towns downstream.”
“A filing on May 26, 2006, by Thomas Berliner, an attorney for the State Water Contractors, and Douglas Adamson, an attorney for the Metropolitan Water District of Southern California, discounted the risk. It urged FERC to reject the request to require that the emergency spillway be armored, a job that would have cost tens, if not hundreds of millions of dollars.
“’The emergency spillway was designed to safely convey the Probable Maximum Flood and DWR has reviewed and confirmed the efficacy of the PMF hydrologic analysis for Oroville Reservoir,’ the attorneys noted.
“Ultimately, they were successful. FERC did not require the state to upgrade the emergency spillway.”
