There are over 75,000 dams over 3 feet in the United State. Only 2,400 - 3% - currently function to produce hydroelectric power. When a river dammed, it never functions the same as a free-flowing river. Reservoirs created by most dams irreversibly flood valleys, destroy native habitats, towns, and farmland. A dam also impedes access for animal species to migrate upstream and downstream, inhibiting natural migration patterns.
The Penobscot watershed is home to 11 species of sea-run fish, species that spend most of their lives in the sea and migrate to fresh water to breed. All native sea-run fish in the Penobscot watershed, and many river across the nation, have suffered severe losses due to dams. In June 2012, The Penobscot River Restoration Trust along with many collaborators, began destruction of the Great Works Dam. Another dam is set to come out in 2014, eventually opening up 1,000 miles of river and tributaries.
Even tough dam removal is becoming more widely accepted, dams continue to be constructed in some of the wildest and more pristine parts of the world.
A film by 70 Degrees West
Music by Ludovico Einaudi - Divenire