by Miriam Trevis
The Record
Oct. 19, 2005
With funding again provided by BC Hydro, under its Bridge Coastal Fish
and Wildlife Restoration Program, rehabilitation work on the lower Elk
River has been completed for this year. The work was commenced last year
in an effort to reestablish the river as a single thread, stable channel.
According to a report from Streamline Environmental Consultants who have been overseeing the work, a series of factors over the past several years have contributed to creating a multi-thread, laterally unstable, gravel in-filled channel in the lower 13km of the Elk River. These factors include valley bottom logging, a natural landslide, water diversion from an adjacent watershed and channel relocation due to road construction. As a result, the report states that there is now a 4 - 7 times increase in the un-vegetated channel width resulting in the loss of fish habitat, eroding banks and an unstable channel.
Work on this project commenced last year when crews from the Mowachaht/Muchalaht First Nations commenced a soil bioengineering process called live staking in which deciduous tree stakes are planted in the exposed gravel bars. The live stakes, which were planted at a density of 17,200 stems per hectare, speed the natural recovery process of the river helping to establish productive riparian forests while increasing channel stability. During seasonal floods over the live-staked gravel bars the stakes promote sediment removal form the river water, which in turn increases the elevation of the gravel bars. Over time as the bars become higher they are inundated by floodwaters less frequently and the river is naturally forced to flow in one channel rather than wander back and forth across the valley bottom.
Last year a total of 1.86ha was planted at three different sites along the lower Elk River. This work continued in September of this year when an evaluation of last years work was completed together with a planting of a further hectare using primarily willow stakes together with some cottonwood and redosier dogwood. The study of last years work is showing encouraging results with an 89% survival rate of the stakes.
For a comprehensive
report on this project, please go to http://www.bchydro.com/bcrp/completed_projects/04CA01a.pdf
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