| Citation |
Meunier, B. and M. Kang. 2014. Aberfeldie Project Water Use Plan. Effectiveness Monitoring of Fish Habitat Works Task 2b, Fish and Fish Habitat Monitoring (Year 1-5). Prepared for British Columbia Hydro and Power Authority, Burnaby, BC. Prepared by VAST Resource Solutions Inc., Cranbrook, BC. |
| Abstract/Description or Keywords |
The Aberfeldie side channel was constructed in the fall of 2008 to compensate for fish habitat and productivity losses predicted to result from the redevelopment of the Aberfeldie Generating Station and associated alterations to the flow regime over the dam and through the diversion reach of the Bull River. The monitoring program ABFMON-5 Effectiveness Monitoring Fish Habitat Works was designed to characterize the effectiveness of the constructed channel to achieve the objectives of its design. The goal of this program was to address management questions presented in Table 1. This report summarises results from the study, ABFMON-5 Task 2B, which monitored fish and fish habitat in the side channel during the first five years of operation. The objectives of this study were to: 1) characterize fish community and fish habitat in the constructed channel; 2) assess water quantity and quality; 3) monitor structural stability; and 4) describe habitat use by target species including spring spawning, summer rearing, fall spawning, and overwintering. The Aberfeldie side channel measures 586 m and is comprised of 4 large pools, 12 glides, 5 riffles, and 4 cascades. It is fed by groundwater and does not have any surface input from the Bull River mainstem. Spawning platforms were constructed at the tail-out of glides to support spawning of target species. A total of 5,290 m2 of aquatic habitat was created through the construction of the channel. While large woody debris were found to provide adequate cover for rearing fish, substrate in the side channel is inadequate to support spawning of target species. Spawning gravel is larger than the gravel size prescribed during the design of the channel and fine sediments are present throughout the constructed habitat. Water quality conditions in the Aberfeldie side channel are below optimal levels for the support of aquatic life. Particularly, dissolved oxygen rarely meets the requirements for rearing and reproduction of fish species as set in BC MoE guidelines (BC MoE, 2006). Dissolved oxygen is particularly poor during winter and restricts the overwintering potential of the side channel for target species. The side channel intercepts enough groundwater to maintain surface flow throughout the side channel during all seasons. However, the side channel does not meet the flow velocity objectives of 0.3 to 0.5 m/s to support spawning and egg development at spawning platforms. There was no spring spawning activity observed in the side channel during the first five years of operation. However, large numbers of Kokanee utilize the side channel in the fall for spawning. A low abundance of juvenile fish were found in the constructed habitat during summer, including Kokanee, Rainbow Trout, Westslope Cutthroat Trout, and Torrent Sculpin. Active bank erosion is present throughout the side channel, likely caused by the steep slope of the banks. Eroded material affects fish habitat availability through the settling of fines in spawning gravel and the reduction of the channel effective width. In conclusion, the construction of the side channel successfully created additional primary and secondary productive capacity. However, the effectiveness of the constructed system in providing suitable habitat to fish is limited, mainly due to water quality, water quantity, and physical habitat issues. The long term sustainability of the constructed habitat is also threatened by active bank erosion and decreasing connectivity with the Bull River mainstem. |
