GMSWORKS-3 Peace River Side Channel Restoration - BC Hydro

6 Side Channel Restoration
Side channels are generated through cyclic or episodic changes in river planform brought about
by physical river processes. Continued morphological processes result in the creation, evolution
and eventual loss of these channels through time, and interruption of one or more of the many
processes can impact side channels. Side channels have been recognized as critical aquatic
habitat, and side channel restoration activities for fish habitat restoration have been practiced
in the Pacific Northwest (PNW) for over 20 years. Many of these projects include:
� Excavation of inlet channels to re‐water side channel habitats,
� Construction of small intake and pipe systems to re‐water side channels,
� Excavation and construction of new open water‐fed connected side channels in the
floodplain, and
� Construction of groundwater‐fed side channels in floodplains.
Within all these works, the complexing of side channels with either wood debris or large
substrate, and modifications of the channel structure by construction of pools or riffles, have
been implemented to improve the fish habitat. Most of these works have been implemented
on relatively small coastal and interior watersheds, and relatively little significant restoration
has been implemented on rivers of a magnitude similar to the Peace River. Typical restoration
drawings for habitat complexing and bank protection have been included in the Appendices.
A contemporary analogue is the lower Fraser River, where channel modifications and gravel
removal for the purpose of maintaining flood capacity have been implemented. These works
have involved opening relic channels to flow and constructing large channels through bars.
These works are temporary, however, and have not been constructed as permanent features.
Another example is the Nechako River, where the construction and assessment of habitat
complexing works for compensation of lost productivity resulting from a reduction in flows has
been studied (NFCP, 1996). These works have been constructed on a river system dissimilar
from the Peace River as it not is subject to a highly variable flow regime, and has much lower
peak flows and mean annual flow.
Following the classification of side channels in the study reach, the following potential
restoration options have been identified. These options are used in the individual assessment
of sites identified in Section 7.
6.1 Permanent Open Side Channels
These channels contain flow through the current range of flows from PCN, but regulation
impacts may have reduced the productive capacity of habitats. The following options can be
considered:
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