A major dam removal project is underway on the White Salmon River in the state of Washington. Video footage of its breach (made available by National Geographic) shows something few living humans have seen but which is already recur in the near future: the removal of a major dam and associated dewatering of its impoundment.
In 1913, the Northwestern Electric Company built the Condit Hydroelectric Project to provide electricity to a nearby paper company and even to feed Portland, Oregon. The dam was rated at 14.7 MW of nameplate capacity - a far cry from the Hoover Dam (2080 MW) or Grand Coulee Dam (6809 MW), but nevertheless a major dam in terms of its power production and significance.
In 1996, increasing pressure on dam owner PacifiCorp to install fish ladders and perform modifications for environmental compliance led PacifiCorp to seek the dam's decommissioning and removal. In 2010, the Federal Energy Regulatory Commission approved the removal of the Condit Dam. In late 2011, contractors breached the dam, draining the upstream impoundment.
If you haven't seen a dam breach before, or if you are simply impressed by the immense power of moving water, you may appreciate the National Geographic video footage of the Condit Dam's breach and the resulting rush of water and sediment.
Now that the Condit Dam has been removed, remediation and restoration efforts are under way. You can track those efforts on the Washington State Department of Ecology's website, as well as on PacifiCorp's website.