Feb 20, 2017
After five years of severe drought, a winter of very heavy rains in Northern California began to strain the flood control infrastructure of the state. The focus of this crisis has been at the damaged Oroville Dam in the foothills of the Sierra Nevada mountains, as 200,000 residents were forced to evacuate their homes for several days, because of the threat of catastrophic flooding.
Oroville Dam is an important part of the massive infrastructure in California that moves water from the Sierra Nevadas down to the extremely profitable industrial farms owned by big corporations and land barons, which use more than 80 per cent of all the water. Oroville Dam is gigantic: high as a major city skyscraper and long as San Francisco’s Golden Gate Bridge. Its reservoir can hold more than one trillion gallons of water. When the reservoir is full, the amount of water that spills out through the main, concrete spillway is equal to the full flow of the Hudson River, roaring down at 40 miles per hour, sending a plume of mist a thousand feet in the air.
On February 7, after several heavy rains, water that cascaded down the main Oroville Dam spillway tore a gaping hole at the bottom, sending massive amounts of debris into the Feather River and crippling the hydro-electric power station. To reduce the risk of further weakening, operators cut back the flow of water going through the spillway. With water continuing to flow into the reservoir, it filled up completely. Water then began to lap over the top of the emergency spillway, something that had never happened since the dam had opened 50 years ago. The emergency spillway is nothing but a 30-foot high concrete wall that is backed by a dirt hillside. The cascading water began to erode the hillside, threatening to undermine the 30-foot high concrete wall at the top.
As rains subsided, repair crews used heavy equipment round the clock to hurriedly patch both spillways with boulders and concrete slurry, while dam operators gradually let reservoir water flow through the damaged spillways, lowering the reservoir’s water level. A few days after the evacuation, top officials announced that it was safe enough to return home.
But the approach of a new series of heavy rain storms would soon test these measures. If a part of the dam would fail, such as the 30-foot high emergency spillway, it would be a true catastrophe. A wall of water would not only flood homes, towns, highway corridors and power stations, but destroy earthen river levees and other parts of the flood control infrastructure, leading to much worse floods and damage – California’s own version of Hurricane Katrina that devastated New Orleans in 2005.
This ongoing disaster could have been prevented. In 2005, three environmental groups and numerous engineers and scientists legally petitioned the federal and state authorities to reinforce the emergency spillway. But officials vetoed the measures, obviously in order to keep the cost of water as low as possible, especially for big agribusinesses.
This is typical of how the massive water infrastructure has been allowed to age without vital repair and maintenance.
And it has turned the massive California system of moving water into a kind of ticking time bomb.