Moses Coulee course southward past the Frenchman Hills and turning west to run along the north face of the Saddle Mountains and rejoin the previous and modern course of the Columbia River just above the main water gap in the Saddle Mountains, Sentinel Gap. Although the Columbia River flowed only for a short period through Moses Coulee, this period included one or more of the tremendous flows from the Missoula Floods. As the Okanogan lobe melted, the upper portions of Moses Coulee were littered with clear evidence of its passing in the Withrow Moraine. The glacier left behind a blanket of glacial
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