Several Northern California towns dodged a fatal bullet Sunday night when a weakened auxiliary spillway at Oroville Dam – the nation’s highest – didn’t collapse.
Authorities had issued evacuation orders for nearly 200,000 people living near the Feather River when it appeared the spillway was in imminent danger of giving way.
The situation remains dicey as operators of the half-century-old, state-owned dam send as much water as possible down the earth-fill dam’s main spillway, which itself had been damaged by erosion, and try to lower Lake Oroville’s level to at least 50 feet below the auxiliary spillway’s lip.
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Meanwhile, many tons of rock will be dumped into holes at the base of the auxiliary spillway to shore up its integrity as authorities await more rain later in the week.
The conditions that filled Lake Oroville to its 3.5 million acre-foot capacity and sent water down the auxiliary spillway – a giant version of a bathroom sink’s overflow – for the first time in its history were not unique.
Heavy rains had pounded the region for weeks, along with heavy snow in the mountains that make up the Feather River’s watershed. Then a very warm tropical storm not only brought more rain, but melted some of that snow, sending a torrent of runoff into Lake Orville and raising it to its brim.
Despite the near-disaster – which could still happen – the system worked largely as intended.
Similar sequences have periodically hit Northern California, often resulting in disastrous floods, and one reason for constructing Oroville Dam was protecting downstream communities, including Oroville, Marysville and Yuba City.
Were Oroville Dam not in place, and had the full brunt of the sudden inflow cascaded down the Feather, it would have devastated those communities, as happened in 1955. The partially constructed dam saved the region from similar damage in 1964.
What almost happened this year is a stark reminder of how much we depend on dams, levees, bypass channels, seawalls and other human efforts to keep destructive tendencies of nature at bay.
There will be investigations into why Oroville’s spillways were less than secure, as there should be.
It’s been reported that 11 years ago, environmental groups warned about the potential for undermining erosion if the auxiliary spillway dumped water on bare earth, as it did, but the water districts that would have had to pay for strengthening it and state officials said it was not needed.
However, recriminations about Oroville, even if deserved, should not obscure the larger lesson that we must be willing to do – and pay for – the maintenance and enhancement of our vital public facilities.
That’s obviously true of dams and other hydrologic systems that supply water and protect us from floods, but also applies to the electric power grid, our roadway network and everything else that a modern civilization needs to function.
It’s a truism that Capitol politicians should remember in light of their decades-long failure to adequately maintain the state’s highway network.
It, too, is crumbling dangerously, albeit in slow motion.