About 26,000 dams in the US pose a high or significant hazard to life and property if a failure occurs

Of the more than 80,000 dams in the U.S., about a third pose a “high” or “significant” hazard to life and property if a failure occurs, according to the Federal Emergency Management Agency (FEMA).

The dam safety community has made a giant leap in its efficiency and effectiveness, with the implementation of Potential Failure Mode Analysis (PFMA), developed originally by the Federal Energy Regulatory Commission (FERC). The program has allowed a large number of people to understand the importance of dam safety, including operators, engineers and managers. It’s been a tremendous help in doing dam inspections, dam safety analysis and so forth

The PFMA can have a beneficial impact on financial and staffing implications because of what the PFMA does. In general, there are 100 ways dams can fail. But for a specific dam, a lot of those ways can be ruled out. That’s what the PFMA does. It looks at the specific dam and it really determines how this particular dam can fail. It can make the monitoring program more efficient and less costly. It also could reveal a potential failure mode that you didn’t realize, which would require additional resources and additional monitoring.

What are the chief causes of dam failures in North America?

Overtopping is the highest and seepage and piping is probably second

Overtopping is something that’s avoidable. You can perform the necessary calculations and develop a “fix” to prevent it. Overtopping might occur because the spillway was inoperable. That’s the type of thing that causes dams to overtop in general, other than extreme floods.