Satellite images have revealed that dozens of dams across the United States — including the largest in Texas — may be at risk of collapse due to shifting soil beneath them. Inspections typically do not account for these movements, suggesting that many of the country’s dams are in worse shape than previously known.
The new findings raise the prospect that thousands of dams we haven’t monitored due to high costs and understaffing could be damaged and at risk of failure. But how big is the problem and is it worth using satellite data to provide early warnings?
Earth shift
In a presentation to the American Geophysical Union in December 2025, scientists used 10 years of radar imagery from the Sentinel-1 satellite to identify dams that have moved as a result of land subsidence or uplift. Depending on the material of the dam, this can lead to the formation of cracks, especially if different parts of the structure move in opposite directions or at different speeds.
“This technology helps us find potential problems and then inform the people in charge,” the lead researcher Mohammad Khorramipostdoctoral geotechnical engineer at Virginia Tech and The United Nations University Institute for Water, Environment and Health, told Live Science.
The results are based on 41 high-hazard hydroelectric plants that are taller than 50 feet (15 meters) and are in “poor” or “unsatisfactory” condition according to Classification of the national inventory of dams. These are dams with known defects that threaten traffic safety and require repairs.
The results are preliminary and have not been reviewed. Still, they show previously unknown weaknesses in dams in 13 US states and Puerto Rico — including Roanoke Rapids Dam in North Carolina and Livingston Dam, the largest dam in Texas.
Some of these high-risk dams are shifting considerably. For example, the northern section of Livingston Dam – which supplies two water treatment plants more than 3 million people in Houston – is falling at a rate of about 0.3 inches (8 millimeters) per year, while the southern portion is simultaneously rising by the same amount.
“This does not mean that part of the dam is collapsing,” Khorrami said. But such height differences need further investigation as they could prove to be a problem, he added. Since these dams are decades old, potentially failing, and affecting both people downstream and energy supplies, deformations in the structure could be catastrophic.
The tragic accident in Libya in 2023 suggests that changes in the country’s altitude cannot be ignored. On September 11, two dams collapsed after extreme rains from Storm Daniel. These faults released 1 billion cubic feet (30 million cubic meters) – or 10,000 Olympic swimming pools – of water on the city of Derna, destroying buildings and bridges and killing up to 24,000 people.
Deformation of the dams due to changes in land elevation probably contributed to the collapses, a 2025 study found. “Satellite imagery results have shown constant and persistent deformations on both of these dams over the past decade,” Khorrami said. “So the dams were already vulnerable.
Khorrami and his colleagues are finalizing the results of their study. The next step will be to create an interactive map or database that policymakers can use to assess the safety of U.S. dams.
“It’s not a substitute for inspections,” Khorrami said. “We’re providing another tool to help find early warning signs if there’s a problem or potential problem with the dam.”
Aging infrastructure, changing climate
But terrain shifts are only one factor that can threaten dams. The US has almost 92,600 dams — more than 16,700 of them have a “high hazard potential”, meaning that if they were to collapse, they could cause loss of life and significant property damage, according to ASDSO. Most were designed more than 50 years ago, and about 2,500 show signs of damage that would collectively cost billions to repair.
Not all of them are monsters like the Hoover Dam; in fact, there are thousands of small dams in watersheds designed to prevent flooding, provide drinking water, and protect natural habitats.
When they were built in the 1960s and 1970s, these dams posed very little risk to people because few people lived nearby. But after several decades, communities sprang up like mushrooms around them, meaning failure can be devastating.
What’s more, most of these dams were designed to withstand the environmental conditions that existed when they were built, but global warming and changes in land use have changed this picture.
Some rivers are declining due to drought, while others have higher levels and flows than 50 to 60 years ago due to increased rainfall and urbanization, which reduces the amount of water stored in the soil. Ebrahim Ahmadisharafassistant professor of civil and environmental engineering at Florida State University, who was not involved in the research, told Live Science.
The weather is also becoming more extreme and unpredictable, increasing the risk of flash floods, Ahmadisharaf said. Until 2025 studieshe and his colleagues found that the probability of a dam overflowing—when the water is so high that it exceeds the capacity of spillways and jets across the dam—has increased at 33 dams over the past 50 years.
The dams with the highest probability of overtopping in this study were large dams with relatively large populations living in cities and small towns downstream—including Whitney Dam in Texas, Milford Dam in Kansas, and Whiskeytown Dam in California. Population centers that could be affected include Waco, Texas, population 150,000, and Junction City, Kansas, population 22,000.
“Overheating is a possible mechanism of dam failure,” Ahmadisharaf explained. “This can lead to catastrophic flooding downstream and subsequent structural failure. The larger the dam and the shorter the distance to infrastructure and people downstream, the more dangerous [overtopping is].”
Money problems
One of the biggest obstacles to safer dams in the U.S. is funding — and the older the dams, the bigger the bill.
“The cost of operating, maintaining and restoring dams can range from the low thousands to millions of dollars, and the responsibility for these expenses lies with the owners, many of whom cannot afford the costs,” Roche said. “Only the most critical dams were to be recultivated estimated to $37.4 billion, a cost that continues to rise as maintenance, repair and restoration are delayed.”
Implementing satellite monitoring of the dams would increase the financial burden — but it may be worth the cost if it helps prioritize repairs and prevent failures, Roche said. According to a forensic expert opinion about the 2017 Oroville Dam overflow incident that caused more than 180,000 evacuations but no deaths, traditional dam inspections don’t always identify important structural problems.
Because only preliminary results are available so far, it’s hard to say whether using satellite data to prioritize dam repairs is useful, Roche said. But in theory, “deformation of dam structures can indicate a problem or deteriorating condition,” he said.
David Bowlesan expert on dam safety risks and professor emeritus of civil and environmental engineering at Utah State University, is more skeptical. “There are many ways a dam can break,” Bowles told Live Science in an email. “Foundation settlement is not the main cause of dam breaks in my experience, but it could be a factor, especially if it’s not monitored and managed.”
Satellites could also play a role in assessing the risks of overtopping the dam, Ahmadisharaf said. Satellite radar images could provide better estimates of water levels and flooding, which in turn could help disseminate warnings earlier.
Overall, satellites could provide a broader picture of risks at dams than we currently have, Ahmadisharaf said. “We can’t monitor everywhere,” he said, “but satellites provide that opportunity.”
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