Dam Effects

The DamEffects graphic explains how dams block and change rivers, to show you how to identify a badly-run dam and the basic ways we can improve dams and restore rivers.

This site shows one small stretch of river and one dam. Many rivers have several dams, exponentially adding stress to the river. Multiple dams intensify impacts, sometimes with serious consequences, such as the failure of pacific salmon runs.

Many of our dams can lighten their environmental footprint, creating a better balance. Yet no dam can eliminate all of its impacts; a dammed river will never function the same as a free-flowing river. Dams have effects that no operational change or new construction can fix, and if those effects are great or costly enough, the dams may be removed.