Dams can have devastating effects on rivers, freshwater ecosystems, and the people who depend on them.
Dams are built to irrigate crops, generate energy from hydropower, improve navigation, control floods, and supply water. But when they aren’t built or operated appropriately, they can ravage rivers and destroy livelihoods.
Very few of the world’s rivers now run uninterrupted from their source to the sea.
The world’s rivers are at risk
. Fragmentation of rivers affects the migration of fish, disrupts the transport of sediments, cuts off floodplains from life-giving floods, and threatens many endangered species. Environmental problems
extend throughout the river basin.
Dams can destroy livelihoods
The devastation of freshwater ecosystems directly affects the livelihoods
of millions of people who live upstream and downstream of dams, especially in developing countries. And this is in addition to the large numbers of people that are relocated to make way for the reservoirs.
…and their costs often outweigh their benefits
Dams are expensive and the projected financial costs
are often inaccurate. The benefits are often overestimated, driven by the incentives of politicians, developers, contractors, consultants, and banks to implement new projects. And since, most of the world's dams are now being built in developing countries, it is even more important that a project makes economic sense.