As a vital part of our nation’s infrastructure, dams need regular inspection, repair and upgrading, and even demolition, when necessary for public safety and if water storage isn’t threatened overall, such as the case with Hetch Hetchy.
Problem dams on the rise in US
Pennsylvania has seen a fivefold increase in deficient dams since 1999.
By Mark Clayton | Staff writer of The Christian Science Monitor
The Kaloko dam in Hawaii stood 116 years – until last year when it collapsed after heavy rains, killing seven.
Potential disaster was averted in April in Hollis, N.H., when a dozen families were evacuated and engineers made a controlled breach of an old pond dam to keep it from failing .
Such incidents are warning signs that many of the nation's more than 87,000 dams are in need of repair. Last month's high-profile collapse of the I-35 bridge in Minneapolis focused America's attention on bridge problems. The nation's dams are worse off.
In 2005, the last time the American Society of Civil Engineers rated America's infrastructure, bridges received a "C" grade; dams earned a "D."
Even that rating may be generous, a Monitor analysis of dam-inspection data shows. Since 1999, the number of "high-hazard" dams rated "deficient" has more than doubled, according to data from the Association of State Dam Safety Officials (ASDSO) in Lexington, Ky. High-hazard dams are those whose failures could cause fatalities. In 1999, the US had 546 such dams rated deficient. By last year, it had 1,333.
A second category of "significant-hazard" dams (so-called because they threaten substantial property loss) saw a rise from 339 to 949 deficient dams over the same period. In all, 2.6 percent of the nation's dams are deficient, according to the ASDSO.
"The growth of deficient high-hazard dams in this country is a major issue," says Brad Larossi, legislative chairman for the ASDSO, which represents dam-safety inspectors in all states. "The trend is rising at such a steep slope, much faster than states can do [dam] rehabilitation. Without question the overall trends are clear."
Several factors are behind the rise. Old dams continue to deteriorate or may fail suddenly because of inadequate spillways and trees growing on dams. Many states don't have enough dam engineers to keep up proper maintenance, causing the repair backlog to grow. And as more homes and businesses are built closer to dams, the hazards increase, a phenomenon dam-safety experts call "hazard creep."
