The elimination of beavers from much of the U.S. West degraded streams and dried up wetlands. Now, artificial dams called beaver dam analogs (BDAs), built by humans but often completed by beavers, maybe the fastest-growing stream restoration technique in the West. Federal agencies, nonprofits, and even private ranchers have installed the structures to return life to deeply eroded streams, and in some cases to help re-establish beavers in long-abandoned territories. Part of the allure is that BDAs are cheap compared with other restoration techniques. The BDA craze is experiencing growing pains, however. Regulators unfamiliar with the approach are sometimes skeptical, and some landowners and government agencies are loath to aid a rodent infamous for felling valuable trees, flooding property, and clogging road culverts.
