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Operational stream rehabilitation trial at Clint Creek, Sewell Inlet

Author(s) or contact(s): H.D. Klassen
Source: Research Branch
Subject: Hydrology
Series: Land Management Report
Other details:  Published 1991. Hardcopy is available.
 

Abstract

Large organic debris was introduced into Clint Creek, a small debris-torrented stream entered Sewell Inlet in the Queen Charlotte Islands in 1988. The study was conducted as an operational stream rehabilitation trial under the Fish/Forestry Interaction Program with the cooperation of Western Forest Products Limited. Three stone blinds, 13 logs, and 6 wads were installed within a 225 m reach in lower Clint Creek. The study design included a pre-rehabilitation survey to determine baseline fish and habitat conditions, an immediate post-rehabilitation survey to monitor initial changes, and a 7-month post-rehabilitation survey to determine structure durability and changes in habitat after a series of winter storm flows. No significant changes in stream width were evident after rehabilitation of Clint Creek. Number of pools in the thalweg increased from 4 before rehabilitation to 18 pools after, and to 13 pools 7 months later. Several sediment lobes dispersed with rehabilitation, burying two of the log emplacements and resulting in a more constant stream slope gradient of 2.9% versus 2.0-4.7% gradient before rehabilitation. Greater channel definition during rehabilitation resulted in a 23% reduction in wetted area, but pool area more than doubled with rehabilitation. Reduction of the majority of overhanging vegetative cover with rehabilitation overwhelmed increases in other forms of rearing habitat cover. However, the critical overwinter rearing habitat tripled and habitat diversity more than doubled in Clint Creek after rehabilitation. Of the 13 log emplacements in Clint Creek, 8 (62%) remained unmoved after a series of large floods over winter. However, 50% of the logs were underscored, reducing average pool depths but also adding diversity and habitat available. Sediment storage areas averaging approximately 14 m2 per log developed over the winter, indicating the log emplacements acted to stabilize the system. Conversely, streambank erosion resulting from rehabilitation average 1 m per log. Construction costs for rehabilitating Clint Creek totalled $6218 and averaged $366 per structure. Restoration guidelines were included in the report to facilitate industry cooperation in future operational stream rehabilitation projects.

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Updated November 27, 2008