The long-talked about removal of two Elwha River dams has started. This project, awarded to Barnard Construction Co. of Bozeman, Mont., signifies the largest dam removal project ever commissioned in the United States. 

And the stakes are high for this undertaking. Not only will the federal government spend about $27 million just to remove the two dams, but also it will spend roughly $350 million to help transform 70 miles of the Elwha River—flowing freely for the first time in 101 years by spring 2014—into a textbook example of natural habitat restoration. At least that’s the hope.

The Elwha River runs north toward the Juan de Fuca Strait right through Washington’s Olympic National Park near Port Angeles. But along the way, the 108-foot high Elwha Dam, completed in 1913, and the 210-foot high Glines Canyon Dam, finished in 1927, stops up the water. Those will be gone within three years, creating an entirely new natural landscape, and one that local tribes and plenty of others hope restore the native, wild salmon population in the area, one that has trickled to next to nothing because of the manmade obstacles.

The removal of the dams themselves has plenty of timing issue built in. First, the water level of Lake Mills behind Glines Canyon will get slowly lowered. Then, the dam gets removed to match up with the new water height. It all starts with a simple 17-foot section and then moves into the next 173 feet, step-by-step, as crews slowly release the river. The gradual process eases the obvious onslaught of water—and sediment—blocked behind the concrete and lets the new riverbanks ease into the task.

On the first day of work, crews utilized a Caterpillar 330 excavator equipped with a hydraulic hammer to chip away what they hope will be two or three feet each day. The excavator not only cracks the concrete, but also is equipped with an additional shears attachment to cut pieces of reinforced steel inside the dam. A bucket attachment pulls the debris into the Lake Mills reservoir, where it will be used to create a new work platform.

When complete, only the concrete spillway high above the river will signify the dam’s once prominent location. It will serve as a viewing platform for the area.

Things will go a little differently at Elwha. There, Lake Aldwell gets lowered 15 feet to the bottom of the spillway gates and then a cofferdam will help move water to one side of the dam. Crews will take out the right spillway first and then work will move to the left. Even the dam’s middle section and pipes that carried water to the powerhouses will get ripped out. At Elwha, some river excavation will be required to get the river running on its proper course, not a diversion channel that is currently part of the dam structure.

For those who want to watch the progress unfold, check out the webcams.