More than 4,400 dams rated unfsafe

NY Times - 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.

"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." (Read more from NY Times)

Also see ERDC Dam Decommissioning Information Site

• FEMA estimates 58,000 large dams will exceed their design life span by 2020.
• ASCE reported 61 dam failures and 520 incidents, 2100 structures classified as unsafe.
• There is a desire to restore threatened and endangered or economically and ecologically significant species affected by dams.