Fraser River environmental watch report July 2, 2020

Fraser River environmental watch report July 2, 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 1, 2020 Daily mean Historic mean Year range
Stuart River @ Fort St. James 14.4 16.5 2000 to 2019
Stellako River @ Glenannan 12.8 15.4 2011 to 2019
Nautley River @ Fort Fraser 15.2 17.0 2007 to 2019
Nechako River @ Vanderhoof 15.5 16.5 2000 to 2019
Nechako River @ Isle Pierre 15.9 17.4 2006 to 2019
Fraser River @ Shelley 09.6 12.6 1994 to 2019
Quesnel River @ Quesnel 08.1 13.8 2006 to 2019
Fraser River @ Marguerite 10.6 17.2 2015 to 2019
Chilcotin River @ Hanceville 11.4 13.4 1996 to 2018
Fraser River @ Texas Creek 12.5 15.8 2006 to 2019
North Thompson River @ McLure 11.0 12.0 2006 to 2019
South Thompson River @ Chase 12.8 15.3 1994 to 2019
Thompson River @ Ashcroft 11.8 14.3 1995 to 2019
Thompson River @ Spences Bridge 13.0 15.3 2006 to 2019
Fraser River @ Big Bar Creek 11.5 NA NA
Fraser River @ Hope 12.5 14.6 1950 to 2019

Fraser River discharge at Hope

Critical levels for fish passage through Fraser Canyon:

Mean Daily Discharge (m3/s)
Long text version

Graph showing Fraser River mean water discharge at Hope. Graph shows 2020 observed and predicted mean daily discharge, 20 year historic median and 20 year return period (1912 to 2019). Trend lines show a steady rate then a gradual decline starting mid-June.

Fraser River water temperatures at Hope

Mean Daily Water Temparature oC
Long text version

Graph showing Fraser River mean water temperatures at Hope. Graph shows 2020 observed and predicted temperatures, highest observed (1950 to 2019) and historic mean (1912 to 2019). Trend lines show an increase from June to a high in August, and a decline to lows in September.