BC Hydro updates flood risk–"The worst is over"
The last round of rain for the multi-day storms will be hitting this afternoon and continue into tomorrow morning. The Puntledge River watershed may see total precipitation of around 40 mm. However in terms of downstream flood impact the worst is over. There are no significant storm systems in the forecast over the next seven days.
The Comox Lake Reservoir is at 136.15 m. This is very near a 50 year historical high reservoir level. Discharges from the dam were reduced slightly for the high tide this morning, but not as much as previous days based in the much lower flows in the Browns and Tsolum rivers.
The current discharge from the Comox dam is about 250 m3/s and this will be maintained for days to lower the reservoir. The public is advised to stay away from the Puntledge River through next week so that BC Hydro can bring levels back were they should be for this time of year and to prepare for future storm systems. The annual ocean king tides, with tides at 5.3 m, take place over the Christmas holiday season.
The Comox Lake reservoir has come up about 3 metres in the past 72 hours. BC Hydro has absorbed as much of the water as possible from these storms while considering our releases downstream for flood risk management. Inflows into the reservoir have averaged over 400 m3/s over this time, peaking upwards of 1000 m3/s, while BC Hydro has only released a maximum of 250 m3/s at low tide and down to as low as 32 m3/s at high tide each morning.
BC Hydro’s aggressive lowering of the reservoir in advance of these storms, particularly on Sunday and Monday, really helped.
Given the very high reservoir conditions on the Campbell River and Puntledge River systems, BC Hydro set up a virtual emergency operations centre. Close coordination, as has been in place all week, was further expanded.
BC Hydro has a comprehensive and robust dam safety program that looks at surveillance to capital projects to maintain our dams. Procedures are in place to have staff monitor the Comox dam at elevation 136.5 m and above 24 hours a day until water levels go back down. The dam is not at risk at those levels though proper monitoring is required should the reservoir continue to rise. Measures were put in place for staffing as there is a potential of hitting 136.5 m tonight.
A final update will provided tomorrow afternoon.