Thursday, February 24, 2011

More than 4,400 dams in U.S. rated unsafe

More than 4,400 of the nation's 85,000 dams are susceptible to failure, says the Association of State Dam Safety Officials. However, "repairing all those dams would cost billions of dollars, and it is far from clear who would provide all the money in a recessionary era," Henry Fountain of The New York Times reports. In Lake Isabella, Calif., the Army Corps of Engineers learned several years ago the man-made dam has a trio of serious issues: "It was in danger of eroding internally, water could flow over its top in the most extreme flood season, and a fault underneath it was not inactive after all but could produce a strong earthquake," Fountain writes. (MapQuest image shows towns immediately downstream from dam; click on image for larger version)
A catastrophic collapse would result in as much as 180 billion gallons of water, along with mud, boulders, trees and other debris, rushing over the 4,000 residents of Lake Isabella down the Kern River Canyon and into Bakersfield, which has about 34,000 people and is 40 miles southwest of Lake Isabella. "The potential is for a 21st-century version of the Johnstown Flood, a calamitous dam failure that killed more than 2,200 people in western Pennsylvania in 1889," Fountain writes. "But corps and local government officials say that the odds of such a disaster are extremely small, and that they have taken interim steps to reduce the risk, like preparing evacuation plans and limiting how much water can be stored behind the dam to less than two-thirds of the maximum."

"It’s not just the loss of life, potentially," said David C. Serafini, lead technical expert for the corps on the project. "It’s the economic damages and the environmental damage, too." At best repairs on the dam would not begin until 2014 and would cost more than $500 million. In the wake of the New Orleans levees failures during Hurricane Katrina, Congress has appropriated money for other federal dam repair projects, but "about two-thirds of all dams are private, and financially struggling state and local governments own most of the remainder," Fountain writes. He notes, "It is difficult to predict how needed repairs to these dams will be financed; legislation to provide federal money to help has languished in Congress." (Read more)

No comments: