A report released by the American Society of Civil Engineers (ASCE) gives America's dams an overall grade of D.
The study -- called the 2013 Report Card for America's Infrastructure -- is an analysis published by ASCE every four years.
America's cumulative infrastructure "GPA" is a D+ with US$3.6 trillion of investments needed by 2020, the report said.
Regarding dams, the average age of the 84,000 dams in the U.S. is 52 years old, the report card said.
"The nation's dams are aging and the number of high-hazard dams is on the rise," ASCE said. "Many of these dams were built as low-hazard dams protecting undeveloped agricultural land. However, with an increasing population and greater development below dams, the overall number of high-hazard dams continues to increase."
According to ASCE, dams fitting the "high-hazard" category numbered nearly 14,000 in 2012, with 4,000 qualifying as "deficient".
Repairs to these high-hazard dams would require a $21 billion investment, ASCE said.
As the study notes, the vast majority of America's dams are not regulated by the federal government, but instead rely on state dam safety programs for inspection. Many state programs lack sufficient resources and regulatory authority, however, leading ASCE to suggest the implementation of more national programs as a means of alleviating the problem.
To view ASCE's dams report card in full, click here.