Adult beavers are nonmigratory. Beavers can usually control water depth and stability on small streams, ponds, and lakes. Lakes and reservoirs that have extreme annual or seasonal fluctuations in the water level are generally unsuitable habitat for beavers. Intermittent streams or streams that have major fluctuations in discharge will have little year-round value as beaver habitat. Stream characteristics such as gradient, depth, and width are determining factors in habitat use by beaver.
Steep topography prevents the establishment of a food transportation system.
Additionally, narrow valley bottoms cannot support the large amounts of vegetation needed by beavers. Consequently beaver populations in narrow valley bottoms are more cyclic than are populations in wider valley bottoms. One study found that 68 percent of the beaver colonies were in valleys with a stream gradient of less than 6 percent. Valleys that were only as wide as the stream channel were unsuitable beaver habitat, while valleys wider than the stream channel were frequently occupied by beavers. Food availablity is another factor determining suitable habitat for beavers.