Americans wondering if a nearby dam might be dangerous can view the status and danger ratings of tens of thousands of dams nationwide using a government-run online database. federal.
But they won’t find the state of the Hoover Dam, which holds back one of the nation’s largest reservoirs on the border of Nevada and Arizona. There are also no conditions listed for California’s Oroville Dam, the nation’s tallest, which underwent a billion-dollar makeover after its spillway failed.
Details of the conditions of these and other major dams are kept secret from the public, listed as “not available” in the National Inventory of Dams.
The lack of publicly available data on potentially dangerous dams has raised concerns among some experts.
“These structures have an impact on people, and that’s obviously what worries us the most. So it’s important to share this information,” said Del Shannon, a Colorado-based engineer who has evaluated hundreds of dams and is president of the US Society on Dams.
For much of the past two decades, the US Army Corps of Engineers has refused to reveal the condition of dams in the National Inventory of Dams – which it maintains – citing safety concerns stemming from the 9/11 terrorist attacks. September 2001.
But in a move towards greater transparency, the Corps launched an updated website late last year that includes hazard ratings and condition assessments of more than a quarter of the roughly 92 000 structures.
Yet the condition of many dams remains a mystery. This is because some federal agencies have not updated their data. The Corps has also authorized federal and state agencies to restrict the release of information about dams they oversee, and some continue to do so citing terrorism concerns.
The Associated Press used information obtained through public records requests to states to supplement National Inventory of Dams data, counting more than 2,200 high-risk dams that are in poor or unsatisfactory condition in 48 states and in Puerto Rico. But conditions remain unknown for more than 4,600 high-risk dams that could lead to loss of life if they fail.
Dam conditions are generally classified 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 ratings. This includes the largest federal dam regulator, the Federal Energy Regulatory Commission, which oversees more than 1,750 dams in 42 states. A FERC spokeswoman said the agency is reviewing its evaluation process and intends to make the terms available this summer.
The Corps also declined to include condition assessments of the approximately 740 dams it owns, including some of the largest in the country. Instead, the agency released its own “risk ratings,” ranging from “very low” to “very high.”
The Garrison Dam, which forces the Missouri River in North Dakota to form one of the nation’s largest reservoirs, is described in the database as “safe” but “high risk.” The Corps says failure of the dam could trigger a cascading failure of downstream dams, resulting in “rapid, deep and life-threatening flooding in many communities”.
No other entity uses the Corps’ risk rating system, making it difficult to compare Corps dams with others. The Corps said it uses risk categories to make repairs “in the most efficient way within a limited budget.”
“The risk assessment information we share is actually better information to help people prepare for a potential problem on a dam,” said Rebecca Ragon, the Corps’ national dam inventory manager.
The PA review also found that some federal departments lack consistent policies for releasing dam data. The Bureau of Land Management and the US Fish and Wildlife Service – both part of the US Department of the Interior – released details of the hazards and condition of their dams.
But the department’s Bureau of Reclamation, which oversees 430 dams in the West, denied the AP’s request for public records on the condition of the dams, citing a legal exemption for “information compiled for enforcement purposes.” of the law”. The bureau said in an email that disclosing the status of the dams “would compromise the protection of our facilities and enable targeted attacks on critical infrastructure.”
Data from other states is also limited or missing.
Alabama has an agency to regulate dams, so there are no condition or hazard ratings for its approximately 2,200 dams.
Illinois doesn’t assign state ratings because grouping dams into categories “is terribly subjective” and “doesn’t have enough value to justify the resources needed to do so,” the engineer said. State Dam Safety, Paul Mauer Jr. However, the state is working with dam owners to make necessary repairs.
New Jersey and Texas provided AP with a total number of poor or unsatisfactory high-risk dams, but did not identify them by name. New Jersey has not released terms for the dam, but plans to do so by the end of May as part of a recent policy change. Texas declined to release the hazard classifications, citing a state law that keeps the “technical details” of critical infrastructure vulnerable to terrorism confidential.
The National Dam Inventory contains neither the hazard classification nor a condition for the Rockwall-Forney Dam, which dams Lake Ray Hubbard to supply water to more than one million people in the Dallas area.
A 2021 inspection document provided to the AP by Dallas shows the dam is classified as high risk and has several issues, including a fractured gate and a large void in the rocks lining the left side. A more in-depth inspection report is not complete.
While an overall condition rating isn’t available, “none of these things are of immediate concern,” said Sally U. Mills-Wright, assistant manager of water production at Dallas Water Utilities.
Without access to information, it is difficult for the public to verify this.
Because dam failures have big consequences, the public should be made aware of a dam’s hazard rating and what’s in its downstream flood zone, said Travis Attanasio, a former dam inspector. who is president-elect of the Texas chapter of the American Society of Civil Engineers.
“You may not necessarily be in a floodplain, but if a dam were to break, you could still face a lot of water,” he said.
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