Aquatic health effects of biotechnical streambank restoration of the Elbow River in an urban environment

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Issue Date

2019-09-17

Authors

Connell, Danielle Susanne

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Subject

Bank stabilization
Biotechnical restoration
Crib wall
Macroinvertebrates
Stream restoration
Willow plantings

Abstract

Streambank stabilization that uses non-living and living design elements, called biotechnical restoration, is an increasingly common approach to stream restoration design. With this increase in use, it is important to ask if biotechnical restoration practices have an effect on the aquatic ecosystem health of a water body. This study collected aquatic macroinvertebrates, basic water chemistry and physical habitat quality data at three sites, evaluating habitat using the United States Environmental Protection Agency (EPA) rapid habitat assessment protocol for biotechnical restored sites. Data was collected and analyzed at three separate sites located within the Elbow River, in the City of Calgary, Alberta. The study sites consisted of timber crib wall and willow plantings with riprap toe treatments and were compared to non-restored reference sites. Overall, changes in macroinvertebrate assemblage response were observed at the timber crib wall restoration site, highlighted by a significant increase of percent Ephemoptera, Plecoptera, Trichoptera (EPT) taxa. Water temperatures and EPA habitat assessment scores also showed a significant response to biotechnical treatments (decrease in mean water temperatures, increase mean habitat scores), demonstrating that biotechnical stream bank restoration treatment can result in a detectable aquatic health change. Improvements to these treatments in future restoration design are recommended

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