Exploration and rehabilitation of hydraulic habitats in streams using principles of fluvial behaviour

• 1 The combination of elements from geomorphology, open-channel hydraulics, and hydraulic habitat requirements of stream fish forms the basis for an ecologically sound ‘soft engineering’ of river channels.
• 2 Interpreting and mapping the hydraulic geometry of streams and locally varied flow conditions can be accomplished with plane table surveys and customized field-data sheets. This information can serve to manage hydraulic habitats preferred by fish.
• 3 The use of fluvial characteristics to design preferred hydraulic habitats is illustrated in two examples: (i) a walleye (Stizostedion vitreum vitreum Mitchill) spawning rehabilitation project undertaken in a stream channelized as a lowland drainage canal, and (ii) a trout (Salvelinus fontinalis Mitchill and Oncorhynchus mykiss Walbaum) habitat-enhancement project to create additional holding and resting areas for adult fish in a stream paved with glacially deposited boulders modified by a road crossing.
• 4 In both examples the ‘soft engineering’ of the river channels enhanced the hydraulic fish habitat.