An increasing number of fish barriers and traps have been constructed in recent years in an effort to achieve regional management objectives. In many instances, unexpected adverse impacts to salmon and steelhead stocks have resulted. This paper documents impacts to be considered in the assessment of whether barriers should be utilized as an enhancement tool. A bioengineering discussion of available barrier technologies follows. We recommend that tributary barriers and traps only be utilized in situations where the potential benefits to a stock clearly outweigh the risks, and then only within specific fish protective guidelines.