A Feasibility Study of Re-introducing a Salmon Population to Jericho Park & Lands Brewer, Julia; Irvine, Keegan; Young, Mason; Wang, Brian
In collaboration with the Jericho Stewardship Group, a team of students from the University of British Columbia has completed a study investigating the feasibility of restoring an ocean-connected stream channel capable of supporting a returning salmon population on the to be developed Jericho Lands, and in Jericho Park in Vancouver, Canada. The Jericho Lands are a 90 acre property on Vancouver’s west side and is one of the last remaining consolidated large sites within the City boundaries (De Silva, 2018). This feasibility assessment was achieved through addressing three major research objectives. The first objective was to assess the water quality of hydrologic inputs into Jericho Park. To assess this objective, water temperature and electrical conductivity (EC) data were collected over a sampling period from November to March and a total metals analysis was completed on water samples. The results of the analyses indicate that over the sampling period, water temperature and EC were within the optimal range for supporting chum salmon. Co ncentrations of Aluminum, Arsenic, Iron, Manganese, and Zinc were in exceedance of British Columbia’s short-term water quality guideline (WQG) for supporting freshwater aquatic life at one sampling location within the central region of Jericho Park. At the concentrations measured, the metals exceeding the WQG could have lethal or sub-lethal effects on salmon, negatively impacting their survival. In order to determine the suitability of this water for supporting a healthy salmon population, more monitoring of water quality in Jericho Park should take place. The second objective was to investigate whether enough water could be supplied to the park in order to support a suitable stream. This was assessed through completion of a water balance analysis and empirical hydrologic modelling of the catchment. The results of this analysis indicate that the current hydrologic inputs into the catchment are sufficient for maintaining a small stream capable of supporting chum salmon under optimal conditions. However, this would require several modifications to the current urban system including completion of the City of Vancouver’s proposed Integrated Stormwater Management Plan (ISMP) to separate and reroute storm sewer pipes, and potential construction of a holding tank to mitigate flashy stream discharge and maintain stable water flow throughout the year. The third objective was to investigate the potential for groundwater input into the future stream system through an analysis of the region’s surficial and subsurface geology. Through this analysis, a moderately productive aquifer that could serve as a source of water for the future stream system was found. However, this aquifer is located below a confining till layer which is preventing natural recharge and upwelling of the water source. Therefore in order to access this water source a well and pump system would need to be installed. To further verify the results obtained in this study, the team recommends implementation of a monitoring program following the development and the implementation of the proposed Integrated Stormwater Management Plan. It is recommended that a long-term monitoring routine of the water quality in Jericho Park is upheld. Long-term water monitoring will allow for better understanding of the change in water quality and long-term suitability of the water source for supporting a healthy aquatic ecosystem. Total metals analyses are the best method for analyzing metal concentrations as they allow for detection of all potentially harmful forms. However for metals where the only dissolved concentrations are reported in the BC WQG (Aluminum and Cadmium), the total metals concentrations likely overestimates the toxicity (BC Ministry of Environment & Climate Change Strategy, 2018), and a dissolved metals analysis may be a better indicator of the water quality. It is also recommended that a stream gauge be implemented in the existing stream to better understand the current water supply. To determine the viability of withdrawing groundwater in this region, well installation and pump testing will be required. Future researchers and city planners may want to consider several additional unknown factors including an analysis of optimal channel morphology to reduce flow velocity and increase water storage capacity, as well as an assessment of the most appropriate surface substrate and surrounding riparian vegetation for supporting optimal salmon spawning conditions.
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