Seven designs of in-stream structures to increase the production of steelhead trout and coho salmon smolts were installed and evaluted in the Keogh River on northern Vancouver Island. Four replicated boulder designs were tested: (1) groupings with cabled log cover; (2) deflectors with log cover attached tot he revetment; (3) deflectors, and (4) V-notch weirs. Three gabion designs, similar but excluding the grouping type, were placed in a second experimental section of the stream. All were installed in riffles, leaving ca. 5 m of riffle upstream to maximize insect drift into the site. The structures were designed to induce scouring during winter freshets, thereby creating turbulent pockets of deeper water or 'runs'.
Ward, B. R., Slaney, P. A.. 1979. Evaluation of In-Stream Enhancement Structures for the Production of Juvenile Steelhead Trout and Coho Salmon in the Keogh River: Progress 1977 and 1978. Ministry of Environment. Fisheries Technical Circular. FTC45