Over 1,680 dams in the United States are considered to be high hazard

According to extended research conducted by the Associated Press, 1,688 dams located in 44 states and the U.S. territory of Puerto Rico are in poor or unsatisfactory condition.

In March 2019, Spencer dam, which is located on the Niobrara River, Northern Nebraska, partially collapsed due to flooding. A year before, the dam was rated in "fair" conditions and did not seem to differ from many facilities currently operative in the U.S. Nevertheless, an additional annotation was included. “Deficiencies exist which could lead to dam failure during rare, extreme storm events.”

The National Inventory of Dams divides the facilities' into three categories: high (potential threat of casualties in case of a failure), significant (no loss of human life is likely to occur but a failure would cause economic and environmental damage) or low hazard. The conditions of the facilities are also rated as unsatisfactory, poor, fair or satisfactory.

Unfortunately, there is not a standard technique for inspecting the dams and this results in a complex data system. For instance, some states do not evaluate dams previously rated as low hazard while others inspect high-hazard facilities infrequently.

The research evaluated many reports from high-hazard dams in poor or unsatisfactory conditions. The most common issues that were detected included water leaks, erosion, vegetation growth and spillways incapable of tackling an extreme flood. The state where most high-hazard facilities (200) in unsatisfactory or poor condition were found was Georgia.

The number of hazardous facilities is probably larger as researchers could not gather all the necessary data about every dam's condition. Some states refused to provide information while others have not evaluated all their dams' conditions for multiple reasons.

Most dams in the US were constructed over 50 years ago and are now obsolete and probably cannot address the current weather conditions as extreme rainfalls and floods have increased due to climate change. In addition, they have to protect more citizens as urban development increases and cities expand close to dam facilities. “There are thousands of people in this country that are living downstream from dams that are probably considered deficient given current safety standards,” Mark Ogden, currently a technical specialist with the Association of State Dam Safety Officials and a formerly Ohio dam safety official, stated.

According to the Association of State Dam Safety Officials, the total cost of repairing the dams in the US is more than $70 billion. Most of those dams are privately owned and owners can not afford or do not will to pay for upgrades.