Oregon High Desert East of the Cascade Range and south of the Blue Mountains, is an area of desolate, high desert. It covers most of five Oregon counties and averages 4,000 feet above sea level. The southwest region is part of the Great Basin. The northern region is part of the Columbia Plateau, where higher levels of rainfall allow the cultivation of alfalfa and hay. Public land within the region, which encompasses more than 30,000 square miles and includes five wild and scenic rivers, is managed by the Bureau of Land Management.