Failure at One of These 15,000 American Dams Would Be Fatal

A quiet crisis is afoot as the nation’s infrastructure ages

A close call at Lake Oroville raises questions about the safety of America's dams. California Department of Water Resources

It’s not often that a hulking piece of infrastructure makes headlines, but the dam at California’s Lake Oroville did just that when it nearly failed last month. Though 180,000 people who were evacuated during the crisis are back home, people are now asking questions about the condition of the nation’s dams. As E&E News’ Jeremy P. Jacobs reports, there’s reason to worry: Nearly 15,500 of America’s dams could cause loss of life if they fail.

The dams in question have been classified “high hazards” because of the danger they present to people. According to the National Dam Safety Program and FEMA, “high hazard” dams will likely result in the loss of life if they fail or are mis-operated. The most hazardous dams are located in populous areas, and their number has risen along with the populations they put at risk. The "high hazard" classification doesn't say anything about the condition of the dams, but, Jacobs reports, the likelihood they will fail is growing.

“By 2025, 70 percent of the country’s dams will be at least 50 years old,” he writes. Experts tell Jacobs that many aging dams were not built to modern standards. The American Society of Civil Engineers agrees—in 2013, the society gave U.S. dams a D on its infrastructure report card, citing the dams’ age and locations as a major risk.

As infrastructure ages, it needs nearly constant maintenance and careful management. But age isn’t the only thing chipping away at dams: Scientists have long warned that climate change is making dams even more vulnerable. In 2011, for example, researchers argued that climate change is making it almost impossible to predict the ways water will flow in the future. “We’re building things on a hydrological lie,” freshwater and adaptation expert John Matthews told Scientific American’s Julia Pyper.

Climate variability—short-term weather patterns like an El Niño event or a hurricane—can overwhelm dams. For example, WIRED’s Nick Stockton notes that California’s extremely wet and unexpected winter proved nearly too much for the state’s system. But longer-term change can be just as dangerous. As the world warms, heavier rains are expected. Rivers courses are expected to change, too, as waterways are pounded by intense storms. That could render the location of present-day dams moot.

The Association of State Dam Safety Officials says that it will cost “well over $60 billion” for the nation to rehabilitate its dams—but that the cost of inaction will be even greater. Will the near-miss at Lake Oroville be enough to prompt Americans to invest more in their dams? The jury’s still out. Meanwhile, time is ticking…and the location of the next close call or actual failure is anyone’s guess.