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Puntledge River flows lowest recorded in 50 years for this time of year
The weather conditions have not changed over the past few weeks and therefore the low water inflow conditions continue for the Puntledge River system, BC Hydro reported Tuesday.
The forecast over the next two weeks also looks dry.
The Comox Lake Reservoir has dropped 30 centimetres or 0.3 of a metre since Dec. 13, and was at 132 metres Dec. 24. At the current rate of reservoir level decline, of three to four centimetres per day, the present river flow rate below the Comox Dam may be sustainable for only about three weeks should the weather remain dry.
At elevation 131.3 and lower, the water discharge may equal the water inflows coming into the reservoir, which are currently about nine cubic metres per second (m3/s).
Out of ongoing concern for salmon habitat, BC Hydro reduced Puntledge River flows Monday evening by about two m3/s to a range of about 13 to 14 m3/s. This reduction will lessen the rate of decline in the reservoir.
The reduction was done by lowering the output of the generating station to five megawatts, with the station now operating at about 20 per cent of capacity. Any further river flow reductions will require the generating station to be shut down.
Should there be a need to shut down power generation sometime in January, BC Hydro will keep the pipeline from the Puntledge Diversion Dam to the generating station full of water so the Comox Valley Regional District and the DFO fish hatchery can continue to draw water.
BC Hydro had a fisheries consultant review key fish habitat areas last week and they will be out again next week to assess the reduction of river flows on salmon eggs.
The concern for incubating salmon eggs with this latest reduction is some gravel areas may not be covered with water. The key spawning areas downstream of the generating station are fully covered with water at about 15.6 m3/s.
The results of the river assessment will be part of the ongoing discussions with Fisheries and Oceans Canada as we try our best to manage through record low water levels for this time of year.
The level of the Puntledge River flow is now unprecedented, being the lowest recorded for this time of year in BC Hydro’s record, as we take further action to conserve water. Correspondingly, the Comox Lake Reservoir is now at the second-lowest level for this time of year in 50 years of record.
Any increase in natural flows from intermittent showery weather or modest snowmelt in Supply Creek and the Browns River (currently flowing at 1.6 m3/s — was flowing at 0.9 m3/s on Dec. 21) that connect into the Puntledge River downstream of the dam, but upstream of the generating station, would help.
BC Hydro will provide its next update in January or sooner should conditions and operational changes warrant it.
— BC Hydro