Research Document 2018/058

Information to support the assessment of the Instream Flow Needs for Fish and Fish Habitat in the Saskatchewan River downstream of the E.B. Campbell Hydroelectric Station

By Watkinson, D.A., Ghamry, H.K., and Enders, E.C.

Abstract

The E.B. Campbell (EBC) Hydroelectric Station, owned and operated by SaskPower, was commissioned in 1963, and is operated as a hydropeaking facility on the Saskatchewan River near Nipawin, SK. SaskPower has requested a renewal of the Fisheries Act authorization for the station and the Fisheries and Oceans Canada Fisheries Protection Program is seeking science advice on Instream Flow Needs (IFN) to help inform a new Fisheries Act authorization. Prior to September 7, 2004 the station could release flows between ~0 m³ s^-1 to ~1,000 m³ s^-1. A condition of the 2004 authorization was a minimum flow release of 75 m³ s^-1. A DFO study report, as well as additional consultant reports, and primary literature publications are summarized in this Research Document to describe the impacts of EBC on downstream fish and fish habitat and to provide IFN recommendations to mitigate impacts on fish and fish habitat.

The natural hydrograph has been severely altered since the station was commissioned, in most part by upstream dams and diversions. EBC is a hydropeaking station and large areas of habitat are typically dewatered daily leading to stranding risk for different aquatic organisms and life stages. The size structure of the fish community downstream of EBC is biased toward large bodied fish, likely due to flow operation and the presence of the dam functioning as a barrier to fish movement. Habitat Suitability Criteria suggest minimum instantaneous flows >75 m³ s^-1 at specific Biologically Significant Periods may benefit fish. In addition, the recovery of Lake Sturgeon may profit from maintaining a high minimum instantaneous flow >700 m³ s^-1 during the first two weeks of the spawning period to maximize potential recruitment success. Rapid down-ramping is likely to increase the risk of fish stranding, specifically when discharges are <500 m³ s^-1. Consequently, a down-ramping regulation could be established to minimize stranding. At flows >1,000 m³ s^-1, the spillway is used. When spill flow resides, fish stranding occurs in the spillway. Adding continuous flow to the spillway could eliminate the need to conduct fish salvage within the spillway. This measure would also increase the available wetted habitat. Re-sculpturing the river edges and the riverbed in the former river channel to connect isolated pools and reduce the bed elevation to below 278.55 m above sea level may also be considered to reduce stranding. Allowing occasional flows >1,000 m³ s^-1 will provide additional flooding and connectivity in the Saskatchewan River Delta and the potential to increase fishery productivity in the Saskatchewan River system.

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