Foster Coulee Cordilleran Glacier moved down the Okanogan River valley and blocked the ancient route of the Columbia River, backing up water to create Glacial Lake Columbia. Initially, floodwater discharged from Glacial Lake Columbia by running up through the head of Grand Coulee and down through Foster Coulee to rejoin the Columbia River. After the floods, meltwater from the glacier reversed course and flowed east through the coulee, forming a hanging valley above the west rim of Grand Coulee and a debris fan on the Grand Coulee floor that can be seen today. As the glacier moved further south, Foster Coulee was
Grand Coulee Dam the reservoir is reserved for tribal hunting and boating. Built in the late 1970s, the Visitor Center contains many historical photos, geological samples, turbine and dam models, and a theater. The building was designed by Marcel Breuer, and resembles a generator rotor. Since , on summer evenings, the laser light show at Grand Coulee Dam is projected onto the dam's wall. The show includes full-size images of battleships and the Statue of Liberty, as well as some environmental comments. Tours of the Third Powerplant are available to the public and last about an hour. Visitors take a shuttle to view