Slocan River Rainbow Trout Habitat Enhancement and Slocan River Riparian Restoration Program Interim Program Evaluation, Update 1.0

Author: Amec Foster Wheeler Environment, Infrastructure

The Slocan River Rainbow Trout Habitat Enhancement Program (SRRTHEP) is a component of the Brilliant Expansion Project Fish and Fish Habitat Compensation Program (FFHCP). The FFHCP was designed to provide suitable compensation for fish entrainment which may occur as part of the regular hydroelectric operations of the Brilliant Expansion facility. The FFHCP is required by the Fisheries Authorization for the Brilliant Expansion Project (FA Authorization #5300-10-022; DFO 2004) and consists of two components: 1. Construction of 15 instream fish habitat structures; and 2. Riparian restoration component titled the Slocan River Riparian Restoration Program (SRRRP). The goal of the FFHCP is to increase the Rainbow Trout (Oncorhynchus mykiss) population in the Slocan River by 250 adult or sub-adult individuals (CPC 2009). The instream fish habitat structures were designed to provide 175 fish and the riparian restoration program would provide the remaining 75 fish (DFO 2004).

The number of Rainbow Trout at instream fish habitat structures have increased since the structures were installed. It can be stated with 50% certainty the structures provide habitat for an additional 65 fish and with 95% certainty they provide habitat for an additional 41 fish. However, there is only 55% certainty that the population of Rainbow Trout in the Slocan River (i.e. at the reach level) has increased as a result of the structures. The structures are, in general, providing suitable habitat that is being used by RB. However, the number of RB using these structures is far less than what was anticipated at the outset of the program. Modeling of RB abundance at the reach level does not suggest the additional habitat has resulted in an increase in the total number of RB in the Slocan River; fish may be moving to the structures from other areas to use the optimal habitat created by the structures. Monitoring of RB at the structure and reach level has provided a consistent method of measuring the RB population and has been bolstered by the evaluation of observer efficiency in the system. The number of MW using the structures appears to have increased over time, however, the large variation in observations has resulted in statistically insignificant results.

Factors other than adult RB rearing habitat may be limiting the population of RB in the Slocan River. Analyses indicated annual high water temperature in the Slocan River was not a significant predictor of adult population change during a given year. However, Slocan River summer water temperature consistently exceeded optimal conditions for RB rearing (>18°C). Although high summer water temperature may not be having an immediate impact on the adult population, temperature may still be a factor limiting other life stages of Rainbow Trout such as juvenile rearing. Other factors limiting RB population growth in the Slocan River may also include limited spawning habitat, limited temperature refugia, poaching and other angling practices.

Reassessment has only been completed at half of the riparian restoration projects completed to date as a result of the the monitoring schedule, making it difficult to draw conclusions about the overall improvement of riparian function along the Slocan River due to the SRRRP at this time. The lineal length of riparian restoration projects completed to date (approximately 6.7 km) has exceeded the suggested length required to generate habitat for 75 sub-adult/adult RB (4 km; GG
Oliver and Golder 2004). The comparative stream bank assessments suggest an equal number of the projects reassessed have improved the quality of habitat along the riparian/foreshore interface as those that have remained stable while two projects have degraded over time. Though detailed evaluation of major riparian projects involving an instream habitat component has been limited, preliminary review suggests these projects may have a more immediate and potentially
effective impact on improving riparian and instream habitat. Moving forward, a broader evaluation of the status of riparian habitats along the entire river could be useful in directing future efforts towards locations for major or side channel restoration projects that are most useful for various RB life history stages and strategies. The monitoring protocol for evaluating these projects is extensive and the stream bank assessments can be used to evaluate changes in riparian function
through time but these projects will likely not be quantifiable in terms of the number of fish they are producing.

Stewardship actions and increased awareness of watershed health due to this project may not be statistically quantifiable, but are significant and should not be discounted. Over 33 landowners in the Slocan Valley and numerous volunteers have partnered in SRRRP riparian restoration
projects. Engagement of Slocan Valley residents has also occurred during various public outreach events including school visits, presentations and workshops where the SRRRP is discussed. How these efforts translate in terms of the fish production target is not possible but these efforts are important in fostering a local awareness of what constitutes healthy riparian and aquatic habitats.

The number of Rainbow Trout at instream fish habitat structures have increased since the structures were installed. It can be stated with 50% certainty the structures provide habitat for an additional 65 fish and with 95% certainty they provide habitat for an additional 41 fish. However, there is only 55% certainty that the population of Rainbow Trout in the Slocan River (i.e. at the reach level) has increased as a result of the structures. The structures are, in general, providing suitable habitat that is being used by RB. However, the number of RB using these structures is far less than what was anticipated at the outset of the program. Modeling of RB abundance at the reach level does not suggest the additional habitat has resulted in an increase in the total number of RB in the Slocan River; fish may be moving to the structures from other areas to use the optimal habitat created by the structures. Monitoring of RB at the structure and reach level has provided a consistent method of measuring the RB population and has been bolstered by the evaluation of observer efficiency in the system. The number of MW using the structures appears to have increased over time, however, the large variation in observations has resulted in statistically insignificant results.

Factors other than adult RB rearing habitat may be limiting the population of RB in the Slocan River. Analyses indicated annual high water temperature in the Slocan River was not a significant predictor of adult population change during a given year. However, Slocan River summer water temperature consistently exceeded optimal conditions for RB rearing (>18°C). Although high summer water temperature may not be having an immediate impact on the adult population, temperature may still be a factor limiting other life stages of Rainbow Trout such as juvenile rearing. Other factors limiting RB population growth in the Slocan River may also include limited spawning habitat, limited temperature refugia, poaching and other angling practices.

Reassessment has only been completed at half of the riparian restoration projects completed to date as a result of the the monitoring schedule, making it difficult to draw conclusions about the overall improvement of riparian function along the Slocan River due to the SRRRP at this time. The lineal length of riparian restoration projects completed to date (approximately 6.7 km) has exceeded the suggested length required to generate habitat for 75 sub-adult/adult RB (4 km; GG
Oliver and Golder 2004). The comparative stream bank assessments suggest an equal number of the projects reassessed have improved the quality of habitat along the riparian/foreshore interface as those that have remained stable while two projects have degraded over time. Though detailed evaluation of major riparian projects involving an instream habitat component has been limited, preliminary review suggests these projects may have a more immediate and potentially
effective impact on improving riparian and instream habitat. Moving forward, a broader evaluation of the status of riparian habitats along the entire river could be useful in directing future efforts towards locations for major or side channel restoration projects that are most useful for various RB life history stages and strategies. The monitoring protocol for evaluating these projects is extensive and the stream bank assessments can be used to evaluate changes in riparian function
through time but these projects will likely not be quantifiable in terms of the number of fish they are producing.

Stewardship actions and increased awareness of watershed health due to this project may not be statistically quantifiable, but are significant and should not be discounted. Over 33 landowners in the Slocan Valley and numerous volunteers have partnered in SRRRP riparian restoration
projects. Engagement of Slocan Valley residents has also occurred during various public outreach events including school visits, presentations and workshops where the SRRRP is discussed. How these efforts translate in terms of the fish production target is not possible but these efforts are important in fostering a local awareness of what constitutes healthy riparian and aquatic habitats.