BC Hydro: Puntledge River Operations Update

December 14, 2018

From BC Hydro:

Since the last operational update, the forecast has significantly worsened in potential inflows into the Comox Lake reservoir. Precipitation rates and the rising and falling of the freezing level are key considerations as we look at these series of storms well into next week. Rain, snow, and some snowmelt will take place. Given the forecast we have moved into a more aggressive flood risk management operation and will be operating the spillway gates at maximum capacity at the Comox dam during low tides to help control  the reservoir level and consider downstream interests. The flows will be high and dangerous and we continue to advise the public to stay away from the Puntledge River through next week as flows will be going up and down several times per day as we consider ocean tides.

We moved to fully raise the two spillway gates at the dam wide open last night. The downstream discharge went as high as 173 m3/s before lowering the gates and reducing the flow down to about 45 m3/s for this morning’s high tide. We hold water back for four hours during the high tide. We will then again raise the gates wide open and the water release may go above 180 m3/s. This type of operation may happen several times per day through next week. If the storm systems lessen then our discharges will be reduced to maintain the reservoir level.    

The Comox Lake reservoir is currently at 134.5 metres and rising given the current flow rate into the reservoir is 254 m3/s, while only about 45 m3/s is being released downstream.  Our goal is to have it near 134 metres if possible – this is dependent on inflows into the reservoir.

Since December 11, about 187 mm of precipitation has fallen at the Cruikshank River.

The Cruikshank River is flowing into the reservoir at about 130 m3/s and is beginning to level off. The Browns River is flowing at about 60 m3/s and the Tsolum River at about 112 m3/s.

At this time we see low risk of isolated downstream flooding.