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INTRODUCTION Streams are altered for highway construct on, flood control, mlnlng, land reclamation, navigation, and other reasons. T ese alterations are often engineering answers to problems that clearly a e interdisciplinary. Stream channelization is a form of alteration which u ually results in straightening the channel, thereby reducing the length of th original channel and increasing the gradient and water velocity. In addition1 streambed substrate is removed, pools are usually converted into riffles or r ns, and vegetation along the streambank is removed. Following channelizat on, streambeds are known to remain unstable for some time (Campbell, Kumar, and Johnson 1972). Unstable substrate is believed to be the most significant factor related to changes in fish and invertebrate populations following channelization (Etnier 1972). Environmental changes of this kind have been shown to be detrimental to the habitats of both aquatic and terrestrial orgarisms. I Public awareness of man1s detrimental e~fects to the environment has received much interest recently (McEvoy 1973~ and people will demand more ecological and environmental considerations In water project planning in the future (McCloskey 1973). McCloskey has poin ed out that the public environ- mental movement has had a great impact in th planning of water projects, particularly in the West. In the early 1970s, the public qUestion~d the use of federal and state funds for stream channelization because of ~he detrimental impacts to the environment. As a result, hearings were he~d on stream channelization during the 1st session of the 92nd U.S. Congress ii May and June, 1971. After the hearings, several in depth reviews were mad of the environmental impacts to natural resources from stream alteration prjects (Little 1973, U.S. House of Representatives 1973). The report to the U~S. Council on Environmental Quality stated that at least 320,000 kilometers (20b,000 miles) of waterways have been developed or modified in the United States ~ince the early 1800s without proper planning, engineering, or finanCing (Littl~ 1973). The report also stated that about 56,000 kilometers (35,000 miles) of ~tream channels have been modified by small watershed programs since 1940 by ~he Corps of Engineers and Soil Conservation Service. The larger federal rlood control and navigation projects of the Corps of Engineers and Bureau of Reflamation are not included in this mileage. In 1972, the Western Association of State Game and Fish Commissioners adopted a resolution that vigorously opposes publicly funded stream channel- ization programs until natural resource va~ues and recreation opportunities are comprehensively evaluated. I I i In the Intermountain West, stream ch~nnelization has been inventoried in Montana and Idaho. Altered stream channels in 13 Montana streams produced only I I i I