In the period from early pioneer days to the present time, the land scape has changed materially — farms new cover rich bottom lands, forests have been cut over, and forage resources have been impaired by unwise land uses. The return of beavers has brought complications in connection with farming operations that necessitate the removal of colonies from localities where they are harmful to places in which they may prove of value. Mountain tributary streams in National and State forests, and in game refuges and other streams far enough from roads, trails, and cultivated fields to prevent damage, offer Suitable locations for the beaver, whose dam-building activities are powerful aids in ?ood control and in the conservation of water resources. The threat to western irrigation reservoirs of the precipitation of sediment from eroded soils is partially alleviated by the formation of thousands of settling basins by this rodent, one of nature's master engineers. Conservation of the beaver deserves consideration for economic as well as sentimental reasons. Norm — This bulletin supersedes, with minor revisions, Farmers' Bulletin 1768, issued in 1937 by the U. S. Department of Agriculture — a contribution of the Bureau of Biological Survey, which was consolidated in 1940 with the Bureau of Fisheries to form the Fish and Wildlife Service, U. S. Department of the Interior.