Damage by beavers is limited. Their dams occasionally flood roads and rarely fields. In some parts of eastern Washington, where fruit raising is an important industry, an individual beaver may cause considerable damage by cutting valuable trees. Ornamental trees may be damaged near the larger cities. Beavers living in Lake Washington in almost the center of the city of Seattle, caused some damage to ornamental trees on the University of Washington Golf Course. Canals and dams in small streams and ditches in areas where stock raising is practiced, flood stock food and sometimes form mudholes or bogs where stock might be trapped. Where individual beavers are doing damage they are trapped and killed, or are live-trapped and transported to more favorable habitats. In places where any beaver may be potentially dangerous, as in the fruit-growing areas of eastern Washington or stock-raising areas in western Washington, their numbers should be kept down by continued trapping. [Illustration: FIG. 102. Forest road flooded by beavers which built a dam on the upstream (left) side of a bridge; Tronson Creek, Blewett Pass, Wenatchee National Forest, May 13, 1938. (Fish and Wildlife Service by Victor B. Scheffer, No. 30.)] Probably the greatest value of beavers lies in the impounding of water by their dams. This is especially true in the arid mountains of eastern Washington and in the logged-off or burned-over parts of western Washington. These ponds prevent erosion, raise the water table and so stimulate the growth of vegetation, insure greater regularity of stream flow, provide suitable water for trout and muskrats as well as some breeding grounds for waterfowl. On burned-over or logged-off land, the greatest, and often the only, growth of new conifers is in the vicinity of beaver ponds. In the vicinity of beaver dams, rich growths of willows and other deciduous vegetation provides food and cover for deer and fur-bearing mammals. [Illustration: FIG. 103. Distribution of the beaver in Washington. A. _Castor canadensis leucodonta._ B. _Castor canadensis idoneus._] Trapping of beaver for their fur at present is not a private enterprise but controlled trapping by the state adds to public funds. =Castor canadensis leucodonta= Gray _Castor canadensis leucodonta_ Gray, Ann. and Mag. Nat. Hist., 4 (ser. 4):293, October, 1869. _Castor canadensis pacificus_ Rhoads, Trans. Amer. Philos. Soc., 19 (n. s.):422, September, 1898 (type from Lake Keechelus, Kittitas County, Washington). _Type._--Obtained by Dr. Robert Brown, probably on Vancouver Island, British Columbia. _Racial characters._--Large size; reddish color; elongate skull. _Distribution._--Found over all but the southwestern corner of the state. The most westward locality from which specimens have been examined is Lake Crescent (U. S. N. M.).