The following is a partial list of dams and reservoirs in the United States. There are an estimated 84, dams in the United States, impounding , mi ( , km) of river or about 17% of rivers in the nation. This list is incomplete; you can help by expanding it. 29 Apr Reservoir creating. Electricity producing. Flood preventing. To tweak a song title from Rodgers and Hammerstein's “South Pacific,” there is nothing like a dam. In a country where thousands of man-made structures have been erected to impound rivers and other bodies of water, a select few dams have. All charts, queries and maps reflect the most current National Inventory of Dams (NID) database. State and federal dam regulators provided their data from August to January for inclusion in the database. Please be aware that inspection and EAP dates reflect data, so any inspections or updates.