Restoring a Salmon Spawning Stream to the Jericho Watershed
Creators: name: Li, Lucy
name: Stewart, Laura
name: Yuan, Daixuan
name: Wen, Chris
Publisher: name: The University of British Columbia
Year: 2018

description: The Jericho Lands is a 21-hectare plot of land located in the West Point Grey neighbourhood of Vancouver. It is directly upslope of Jericho Park, which itself has significant ecological and recreational value to the community. Jericho Lands is currently planned to undergo redevelopment in the coming years by the Musqueam, Squamish, and Tsleil-Waututh First Nations and is currently in the research, planning, and consulting stage. This redevelopment could make it possible to restore salmon-spawning streams that once existed in the area. The aim of this project is to explore the possibility of re-introducing salmon to Jericho Park. The main objectives of our project are to explore the characteristics of Jericho Park using GIS software, explore water sources, propose potential locations for possible holding ponds, and propose possible stream routes for these holding ponds. Chum were determined to be the best species for reintroduction at the park based on a meeting that we had with Scott Hinch, an aquatic ecologist at UBC. The criteria for streamflow was based on the biological needs of salmon. The amount of water needed to sustain a healthy salmon stream was determined to be 40 L/s or 0.04 m³/s (1.5 m wide, 0.13 m deep, flowing at 0.20 m/s). This streamflow would be needed from November to the end of April. In other months (May through October), we set a target streamflow (0.00039 m³/s to 0.0027 m³/s) to mitigate potential evapotranspiration in order to keep the channel wet, but not necessarily flowing. There are currently two watersheds contributing to Jericho Park, which provide two possibilities for stream channel locations. The western watershed is 230 ha and eastern is 264 ha. Both have 62% impervious cover (including roads, roofs, etc.). Because of the urban nature of the system, streamflow is likely to rely on storm sewers and streamflow might be very flashy (i.e., short floods followed by periods of very low flow). An analysis of surface water was carried out to estimate potential streamflow. This was done using water balance equations with weather parameters from 2016, parameters obtained from literature, municipal databases, and GIS software. Weather data from 2016 was used for water balance equations. Stormwater would be the main water source for the stream. However, not all watersheds could reach the target flow rate (0.04 m³/s). The average streamflow from November to April would be 0.05 m³/s in the eastern watershed, which is greater than the target flow rate. Meanwhile, the western watershed only has average streamflow of 0.024 m³/s during this period. Holding ponds could be used to help prevent the flashiness of a stream and store water for use in April, but a holding pond would have to be enormous (103680 m³, the size of a football field 19 m deep) to give 0.04 m³/s of water for one month. HVAC (Heating, Ventilation, and Air Conditioning) systems could produce 14 to 46 L/day/1000 ft² during the summer. This would be enough, given a reasonable number of newly developed buildings in Jericho Lands, to mitigate evapotranspiration in the stream channel, and help mitigate water losses from evaporation and plant uptake in the channel and the existing ponds in Jericho Park. However, it would not be of use for the spawning season as there would be no Chum in the stream throughout the summer. We have proposed two possible locations of holding ponds as well as the resulting stream that would be constructed at each possible location shown in Figures 9 and 10, section 3.5. The holding pond proposed in Figure 9 could be possible with sufficient groundwater pumping, although dry seasons could be a problem. However, the holding pond proposed in Figure 10 would provide enough water during a dry season due to its water input mainly sourced from the eastern stormwater catchment.