In light of recent research revealing dire hazards associated with the nation’s crumbling dam infrastructure, these remarks are alarming. The vast majority of these structures are highly prone to overtopping. With at least 90,000 dams of all sizes across the country, a majority were built around the time of the Great Depression. The recent study published in Nature Communications is an urgent wake-up call to act. We need to reimagine and upgrade our critical infrastructures before the next confluence of catastrophes strikes.
The study modeled 33 dams across the state of Iowa from a 50-year perspective, using extensive data to estimate overtopping probabilities. Approximately 34% of dam failures are due to overtopping. This often occurs due to inadequate spillway design, action blockage from debris, or settling at the top of the dam. Alarmingly, the American Society of Civil Engineers rated U.S. dams a D+ in its 2025 infrastructure report card, indicating a concerning state of disrepair and increased vulnerability.
Dam Characteristics and Hazards
Of the 33 dams examined, 30 were noted as large dams, having crest heights of at least 15 m. This study’s findings indicated a growing trend of dams showing high overtopping probabilities. Specifically, there has been a decrease in the share of dams with non-critical overtopping probabilities. This fundamental shift inside the banking sector requires urgent action.
Recently, a number of dams have been found to have large overtopping probabilities. They are Canyon Dam (New Braunfels, Texas), Kanopolis Dam (Marquette, Kansas), Milford Dam (Junction City, Kansas), Somerville Dam (Somerville, Texas), Whiskeytown Dam (Anderson, California), and Whitney Dam (Waco, Texas). The Federal Emergency Management Agency (FEMA) designates 31 of these dams as “high hazard.” Should any one of these dams fail, it would cause an immense loss of life.
“In this study, we showed where hazards from overtopping are greatest, both because of risk of occurrence and possible consequences. It is a guide to where infrastructure spending could have the greatest impact,” – Eunsaem Cho
High-risk structures like bridges and culverts should always be prioritized for safety improvements by municipalities and state agencies. They must equally prioritize rehabilitation efforts to promote the health of all communities.
Implications of Aging Infrastructure
The growing concerns about U.S. dam infrastructure are more serious than ever. Most of these dams were built with the best technology of their day, but that technology is long obsolete. Co-author Ebrahim Ahmadisharaf explains that dam builders did the best they could with what was known decades ago. Ages have changed, he wants to remind you, and aging infrastructure is now a major concern.
“In summary, their study calls for an intelligent and proactive approach to dam safety and resiliency. “We have to plan upfront for this potential risk,” Ahmadisharaf added. To look at trends and risk in a complete, forward-looking manner, the researchers studied each possible 30-year period that fits within the full 50 years of data.”
“This study represents the first step toward a comprehensive assessment of dam overtopping probabilities in the U.S. Understanding this potential risk is crucial for protecting communities and prioritizing dam rehabilitation before catastrophic failures occur,” – Eunsaem Cho
While this research foreshadows an increasingly risky future for critical overtopping events, it also provides a limited opportunity to address these challenges with strategic investments and a long overdue effort to modernize what we have.