BC Hydro: Puntledge River Operations Update
July 27, 2018
From BC Hydro:
We have been conserving water since June and that action has helped manage through a dry period as we balance the system water use interests. We are currently running the Puntledge River generating station at 37% of capacity.
We are discharging about 17 m3/s below the Comox dam into the Puntledge River. However, total water inflow into the reservoir is only about 7 m3/s, which is 40% of historical average for this time of year. The minimum fish habitat flow is about 16 m3/s. Given the dry conditions and forecast, and with the snowpack depleted, we need to proactively lower the river flow in case it’s a dry summer and early fall, and have enough water for the fall salmon migration and domestic water supply. By reducing river flows down to 13 m3/s, we are reducing the risk of further flow reductions later in the season.
From February 2018 to date, the total water inflows into the reservoir are about 75% of average, which is the eighth driest in 50 years of record.
BC Hydro, with government fish agency awareness, will lower the Puntledge River flow to about 13 m3/s on August 2. Power generation will then move down to about 25% of capacity. The river flow rate at Nymph Falls and Stotan Falls section of the river will remain unchanged at about 6 m3/s for fish habitat within that 5 to 6 km stretch of river. The difference in flow rate will be noticed below the generating station or fish hatchery, and in areas like Puntledge Park, which is a popular tubing area.
Cumulative precipitation in the watershed is been tracking below average since March. It was the driest March on record, which goes back 37 years, and it was the second driest May on record. July is on track to be the eighth driest on record.
The Comox Lake Reservoir is currently at 134.55 metres. The reservoir level is dropping by about 4 cm per day. The downstream release of water suitable for fish may become critical should the reservoir hit 131 metres. The reservoir storage is full at 135.33 metres.