Condition of some U.S. dams kept secret in national database

Americans wondering whether a nearby dam could be dangerous can look up the condition and hazard ratings of tens of thousands of dams nationwide using an online database run by the federal government.

But they won’t find the condition of Hoover Dam, which impounds one the nation’s largest reservoirs on the border of Nevada and Arizona. Nor is there any condition listed for California’s Oroville Dam, the country’s tallest, which underwent a $1 billion makeover after its spillway failed.

Details about the conditions of these and other prominent dams are kept secret from the public, listed as “not available” in the National Inventory of Dams.

The lack of publicly available data about potentially hazardous dams has raised concern among some experts.

“These structures impact people, and this is what we’re obviously most worried about.

So it is important to share this information,” said Del Shannon, a Colorado-based engineer who has assessed hundreds of dams and is president of the U.S. Society on Dams.

For much of the past couple of decades, the U.S. Army Corps of Engineers declined to reveal the conditions of dams in the National Inventory of Dams — which it maintains — citing security concerns stemming from the Sept. 11, 2001, terror attacks.

But in a move toward greater transparency, the Corps launched an updated website late last year that includes hazard ratings and condition assessments for more than one-quarter of the roughly 92,000 structures.

Yet the status of many dams remains a mystery. That’s because some federal agencies failed to update their data. The Corps also allowed federal agencies and states to restrict the release of information about the dams they oversee, and some continue to do so citing terrorism concerns.

The Associated Press used information obtained by public records requests to states to supplement data in the National Inventory of Dams, tallying over 2,200 high-hazard dams that are in poor or unsatisfactory condition in 48 states and Puerto Rico. But the conditions remain unknown for more than 4,600 high-hazard dams that could cause a loss of life if they fail.

Dam conditions typically are categorized as satisfactory, fair, poor or unsatisfactory.

In the Corps’ database, nearly two-thirds of the 18 federal entities that own or oversee dams provided no condition assessments. That includes the largest federal regulator of dams, the Federal Energy Regulatory Commission, which oversees more than 1,750 dams in 42 states. A FERC spokeswoman said the agency is overhauling its assessment process and intends to have conditions available this summer.