Fixing All Deficient US Dams Would Cost $70 Billion; Not Fixing Them Would Cost Much More [View all]

[hatrack]

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Martin McCann is the director of the National Performance of Dams Program at Stanford University. McCann thought that the Oroville failure was a wakeup call for an industry that had mobilized to reduce risk following a string of deadly dam disasters in the 1970s, but had grown complacent after years of relative calm. Oroville should have changed that, he said. California’s dam safety program was considered the best in the country: well-funded with professional staff who were experienced and technically competent. But even that was not enough to prevent a near calamity at Oroville, a dam owned by the California Department of Water Resources.

“What Oroville told us was: good may not be very good at all,” McCann told Circle of Blue, referring to the perceived quality of a dam safety program. “Or, being the best may not be very good at all, which leaves everybody else that much further behind.” McCann agreed with the conclusions of an independent review of the Oroville incident: that California’s dam oversight suffered from systemic failures. That conclusion could be applied nationwide, he said.

Engineers and regulators have much to keep their attention. Climate change is the risk that is front of mind. A warming atmosphere holds more moisture, which is leading to larger storms. Between 5 and 8 inches of rain fell across central Michigan in the three days before Edenville Dam failed. The National Weather Service estimated the probability of such rainfall occurring in a year at 0.5 percent. More severe floods could produce a “greater risk of infrastructure failure in some regions,” according to the federal government’s fourth National Climate Assessment, which was published in November 2018.

But, as Lall points out, climate change is not the only risk factor. The rainstorm in Michigan was rare but not outside the bounds of what was historically possible. Urbanization is another consideration. Cities have grown up around dams. More hard surfaces — parking lots, roof tops, roadways — increases runoff into rivers and lifts the height of floods. Dams might not have been designed for this additional stress, especially if silt has reduced their storage capacity or, as in Oroville’s case, if their design is flawed. “Things will get worse,” Lall said, referring to the effects of climate change. “But even if they don’t get worse the situation is bad.”

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https://www.circleofblue.org/2020/world/countrys-aging-dams-a-sitting-duck-facing-a-barrage-of-hazards/