From the Document: "Dams provide various services, including flood control, hydroelectric power, recreation, navigation, and water supply, but they require maintenance, and sometimes rehabilitation and repair, to ensure public and economic safety. Dam failure or incidents can endanger lives and property, as well as result in loss of services provided by the dam. Federal government agencies reported owning 3% of the more than 90,000 dams listed in the National Inventory of Dams (NID), including some of the largest dams in the United States. The majority of NID-listed dams are owned by private entities, nonfederal governments, and public utilities. Although states have regulatory authority for over 69% of NID-listed dams, the federal government plays a key role in dam safety policies for both federal and nonfederal dams."
CRS Report for Congress, R45981
Congressional Research Service: https://crsreports.congress.gov/