To restore fish populations
The Colorado River/Colorado River Basin has more than twenty major dams in the river system. However, the Columbia River System has more than four-hundred dams for hydroelectricity and such.
there can be all sorts along major rivers like dams statues.
There were 3 TVA dams on the Tennessee River in Alabama
dams
Hydroelectric dams.
dams
Across rivers and streams.
According to http://govtsecurity.com/news/us-dam-security-0904/ approximately 80,000.
there are 4 major dams Sennar, Aswan High, Roseires and Owen Falls Dam
People in south America build dams on the major rivers to get more electricity. Plus, there is more industrialization in the area.
I have been told that the only two dams you can drive over in the US are The Hoover Dam in Nevada, and the Stevenson Dam in Connecticut.