Water Supply & Demand Project

Fish Flows

Fish-bearing stream

The Okanagan River and its tributary streams are important habitats for the spawning and rearing of salmon, trout (salmonids) and other aquatic life.

Over the last century, fish and wildlife habitat in many Okanagan sub-basins has been degraded or eliminated due to water extraction, flood control structures, and land development.

The amount of water needed in a stream to adequately provide for downstream uses such as drinking water, aquatic habitat, recreation, riparian vegetation, and water quality is termed “Instream Flow”.

Most streams have some level of flow, but flow is no guarantee that all is well for the organisms that depend on the river’s resources.

Instream flow management aims to balance the protection and restoration of lakes, rivers and streams, while honouring existing uses such as the Okanagan’s recreational and traditional food fishery.

While site-specific field studies yield the best estimates of instream flow needs for specific aquatic species, the pace of water allocation decisions requires a method of rapid assessment.

Fisheries biologists and planners may use the project’s Instream Flow Needs Assessment as a starting point to establish preliminary instream flow needs, and then target priority areas for future site-specific research.

It is interesting to note that the choice of how to calculate instream flow needs depends on a variety of factors, including ecological objectives (e.g. maintaining species diversity), the personal or community values that we place on healthy streams, and the overall environmental management strategy to protect fish in the Okanagan.

For example, we may decide to protect a number of healthy sub-basins as ecological reserves, while allowing more intensive development or water extraction elsewhere.

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