Fraser River environmental watch report July 27, 2020

Fraser River environmental watch report July 27, 2020
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Ten-day daily forecasts of lower Fraser River temperature and flow conditions as well as current conditions throughout the Fraser basin are updated bi-weekly from roughly late-June until mid-August. These short-range forecasts are generated using river temperature and river flow forecast models (Hague and Patterson 2014).

The latest research on Pacific salmon fresh water migration suggests there are population-specific differences in temperature and flow tolerance thresholds (Eliason et al. 2011). These differences likely relate back to the variability in the average river environmental conditions experienced by salmon beginning their river migration at different times of the year and along different paths (Farrell et al. 2008). Despite these differences, there are also species-wide thresholds that will result in migration difficulties for most populations of Fraser River sockeye salmon. We provide species-level thresholds as a guide to interpreting the potential effect of current and forecasted river temperature and flow conditions on returning salmon. However, in general, fish historically returning to the Fraser River in the mid-summer will be more tolerant of higher temperatures than those fish returning in the early or late summer or early fall.

Current temperatures
July 26, 2020 Daily mean Historic mean
Stuart River @ Fort St. James 16.9 18.6
Stellako River @ Glenannan 15.5 17.3
Nautley River @ Fort Fraser 18.4 18.7
Nechako River @ Vanderhoof 17.2 17.5
Nechako River @ Isle Pierre 17.4 19.1
Fraser River @ Shelley 11.7 15.2
Quesnel River @ Quesnel 11.2 15.8
Fraser River @ Marguerite 13.7 18.0
Chilcotin River @ Hanceville 15.7 15.4
Fraser River @ Texas Creek 14.8 18.0
North Thompson River @ McLure 12.8 15.0
South Thompson River @ Chase 15.1 19.0
Thompson River @ Ashcroft 16.4 17.3
Thompson River @ Spences Bridge 17.8 17.9
Fraser River @ Big Bar Creek 13.7 NA
Fraser River @ Hope 16.1 17.4

Fraser River discharge at Hope

Critical levels for fish passage through Fraser Canyon:

Mean Daily Discharge (m3/s)

Fraser River water temperatures at Hope

Mean Daily Water Temparature oC

Fraser River discharge above Texas Creek

Fraser River Discharge above Texas Creek

Fraser River water temperatures above Texas Creek

Fraser River Water Temperatures above Texas Creek