Stave River Water Use Plan - BC Hydro

Stave River Water Use Plan
Monitoring Terms of Reference June 13, 2005
Hypothesis H08 establishes the primary pathway by which carbon and other
nutrients enter the food web, and reflects the general growing conditions of
phytoplankton. A predominance of ultra-phytoplankton tends to indicate poorer growing
conditions, which collectively include the influences nutrient levels, water temperature,
light availability etc. (Wetzel 2001). Conversely, a predominance of micro-phytoplankton
indicates an excellent growing environment.
Hypothesis H09 explores the linkage between primary production and fish
production by examining the size structure of zooplankton (secondary production). Of
importance is the density of larger organisms that tend to constitute the majority of
pelagic fish food production.
Hypothesis H010 is an independent test of the impact hypothesis model as it
pertains to the WUP Combo 6 operating strategy.
1.4 Key Water Use Decision Affected
In the absence of reliable predictions on the effect of dam operations on Stave
reservoir productivity, it was assumed that pelagic productivity would remain unchanged
over the spectrum of feasible reservoir operating strategies. However, the CC
recognised that there was considerable uncertainty in this assumption, but had no
information with which to form other, more probable outcomes. This monitor is designed
to:
a) Test the validity of this assumption of no operational impact, and confirm that
pelagic conditions have not worsened with the new Combo 6 operating strategy.
b) Provide the information necessary to promote a better understanding of the
pathways by which operational changes can affect primary productivity (the
chosen indicator variable of fish productivity), and in turn provide better
predictions of operational impacts for future WUP reviews.
In addition, this monitor attempts to develop a better linkage between the effect
of reservoir operations on primary productivity and the potential for fish production.
Collectively, this information will lead to conclusions regarding the expected
benefits of the Combo 6 operating strategy, and whether alternative strategies should be
proposed if these benefits are not realised. Through a better understanding of reservoir
ecosystem dynamics, its may be possible to find improvements to the Combo 6
operating strategy that may increase operational flexibility without compromising
reservoir ecosystem function. Specific actions that may lead to such improvements
cannot be identified at this time because of the complexity of the Stave Lake project.
The complex modelling exercises needed to identify such actions is beyond the scope of
this monitor and should be reserved for future WUP processes.
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