Kettle River Range Mountains, which in turn form part of the Columbia Mountains. The range runs north to south, bordered on the east by the Kettle River and the Columbia River, and on the west by the Kettle River, the Curlew Valley and the San Poil River. The mountainous region begins immediately north of the Canada–US border, at Grand Forks, British Columbia, extending 110 miles (177 km) south to the bend of the Columbia River and Lake Roosevelt, formed by Grand Coulee Dam, where it terminates. The Okanogan Highlands are adjacent to the range on the west, and the Selkirk Mountains are adjacent
Grand Coulee pumped from the Grand Coulee Dam, into Banks Lake to act as an Equalizing Reservoir and irrigation water source. Evidence of the waterfalls includes a plunge basin where the falls began, immediately south of Coulee City. It contains at least of gravel lower than the open flooring of the land. The river above the falls was shallow and much wider than the gorge. Thus, it wrapped around the lip of the main falls creating lateral falls. These flowed until the recession of the main falls denied them water. Northrup Canyon in Steamboat Rock State Park, contains a dry cataract as