Water Storage Levels

The available water storage calculation is based on 100% storage corresponding to the crest of the weir and 0% corresponding to the lake level that can sustain the minimum flow of 7 m³/s. The lake can store water above the crest of the weir, however water stored above the weir is not released into the river at a controlled rate and so it is not considered “available storage”. Prior to July 1st, the target water storage is the crest of the weir. After July 1st, the target for water storage is a regulated rule curve. For Cowichan Lake, the rule curve is the regulated limit set by the Province for the maximum amount of water that can be stored during the Summer and early Fall.  The Cowichan Lake level graph shows the change in lake level throughout the year.

The available water storage calculation is based on 100% storage corresponding to the level of the spillway and 0% storage corresponding to the level of the water intake (the point of withdrawal).  Stocking Lake can actually store up to 0.6 meters above the spillways.  However, water stored above the spillways is not released into the rivers at controlled rates and so it is not considered “available storage”.  The Stocking Lake water storage graph tracks the available water storage through the year.