The warm and dry last half of the summer, and with this trend continuing into early fall, has created very dry conditions and little water inflows into the Comox Lake Reservoir.
BC Hydro has reduced the river flow by a little over one-quarter to conserve water and to be able to sustain a river flow until the fall rains hit.
There has not been a significant rain event since the middle of July and the reservoir has been steadily declining since then. Over the past 45 or so days, BC Hydro has been releasing about triple the water levels down the Puntledge River versus what’s coming into the reservoir.
The lower Puntledge River has a minimum flow requirement of around 16 cubic metres per second (m3/s) to allow the river to be fully covered for salmon migration and spawning. BC Hydro has had to release about 18.5 m3/s from the Comox Dam to maintain the required flow and also allow the regional district and the Fisheries and Oceans lower hatchery to withdraw water.
However, water inflows into the reservoir have been about five and six m3/s. The reservoir was at 132.2 Friday morning and has been dropping by about five to six centimetres per day.
The critical level is in the 131-metre range as it gets constraining on the amount of water that can be released downstream — basically the water inflows into the reservoir would equal the flow down the Puntledge River.
On Thursday, BC Hydro received government fish agency support and Comptroller of Water Rights approval for a water license variance and a conservation flow of 11.3 m3/s. The slow reduction of the river flow takes place over many hours and began last night to have in place this morning.
This revised river flow will lessen the rate of reservoir level decline. BC Hydro will adjust operations accordingly pending the weather conditions over the next month.
BC Hydro is worked with DFO and had crews out first thing this morning for any fish salvage in areas where pools of water will become separated from the main river flow with the exposure of the riverbed in some areas.
Over the past 12 years it has become somewhat common to reduce flows to the 11.3 m3/s range for dry weather conditions at this time of year.
Lastly, BC Hydro’s maintenance work at the generating station has led to some unplanned work that has extended the Stage 3 water restrictions beyond Sept. 28. For more, visit
www.comoxvalleyrd.ca/section_publicaffairs/content.asp?id=8115.
— BC Hydro