After #Oroville, officials across the West review dam safety — @HighCountryNews

New Oroville spillway finish work. Photo credit California DWR.

Here’s an analysis from Emily Benson writing for The High Country News. Click through and read the whole thing. Here’s an excerpt:

To avoid the risk of further erosion, however, both spillways [at Oroville] needed to be patched up before this winter. By early November, following months of ‘round-the-clock work, the California Department of Water Resources announced that Oroville was ready for the rainy season, though final repairs will take another year. And the consequences of the incident could last far longer: Its sheer scale means it has the potential to affect legislation and policy, as did earlier disasters at other dams. Safety officials in California and across the West are already reassessing spillways, updating disaster plans and refining evacuation maps, hoping to prevent a repeat of Oroville — or worse.

Structural failures were the immediate cause of the Oroville catastrophe. The main spillway has successfully handled larger flows than what it saw last February. While it’s not yet clear exactly why it broke apart, some researchers say part of the blame lies in poor design and shoddy maintenance — and that those problems could have been addressed. An independent group of dam experts is investigating what went wrong, with a final report expected by the end of 2017. An interim report released in September notes that there was preexisting damage and repairs at the area that first crumbled. Weaknesses there could have allowed water to get beneath the spillway, potentially blasting apart the concrete from below.

Administrative failures — problems with inspections or regulations — may share the blame for what happened at Oroville. A patchwork of agencies meant to prevent such problems regulates dam safety in the United States. Federal agencies like the Bureau of Reclamation and the Army Corps of Engineers oversee inspection and maintenance at their own dams. Dams that belong to the state, like Oroville, or a utility company or other non-federal entity, are typically under the jurisdiction of a state agency; the Federal Energy Regulatory Commission (FERC) is also involved in dam inspections at non-federal dams with hydropower projects they license, including Oroville…

In Colorado, Oroville confirmed that dam safety officials were already on the right track, says Bill McCormick, the chief of dam safety at Colorado Division of Water Resources. There, the big test came in 2013, when widespread flooding in north-central Colorado driven by torrential rain led to the failure of about a dozen small dams. Nobody was hurt or killed as a result of the failures, “but they did get people’s attention,” McCormick says. (Several people died elsewhere during the flooding.) Another wet season in the spring of 2015 made clear the need to plan for different levels of flooding and dam releases. “Our main lesson from Oroville is that we still need to be vigilant,” he says, “but we’re doing the right things.”

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