Debris cleanup prompts BC Hydro to cut dam flow

CAMPBELL RIVER—River levels downstream of John Hart dam to remain high as Elk Falls spill is increased

BC Hydro crews will be cleaning out debris in the trash racks upstream of the power intake at the John Hart dam this Thursday. To safety complete the work, the water that passes through the intake and down the three penstocks to the generating station will be reduced to a minimum. But the river levels downstream of the generating station will rise because the spill down Elk Falls Canyon will be increased. BC Hydro spokesperson Stephen Watson said the public is advised to stay away from the Campbell River upstream of Elk Falls due to the high and dangerous flows beginning on Thursday before dawn and ending that evening.”The storms in October through December have added significant grassy and woody debris onto the trash racks that keeps debris from entering the penstocks,” Watson said. “This debris is beginning to cause penstock pressure issues and must be removed. The reduction in power generation will allow workers to safely access the upstream side of the trash racks by boat to remove the debris.” The John Hart generating station is currently running at full capacity and power output will be significantly reduced to safely complete this work. Each of the approximately 21 megawatt (MW) generating units will be reduced down to about six MW each, or six cubic metres per second (m3/s) of water discharge. With only about 36 m3/s of water coming out of the generating station, an additional 50 m3/s will be passed down the canyon. The minimum fish habitat flow in the canyon is four m3/s.The Campbell River flow will reduce downstream of the station from about 120 m3/s to 84 m3/s beginning early Thursday morning. The flow will then be increased back to around 120 m3/s when the debris removal is completed, likely Thursday evening.The water inflows from the weekend storm were fairly high and were absorbed into the upstream reservoirs. Upper Campbell Reservoir/Buttle Lake rose about one metre since Friday and is currently at 219.3 metres. With a drying trend now in place, and the system generating stations running near or at full capacity, this will slowly begin to lower the reservoirs down to levels for flood risk management considerations.This is also the one time of year when BC Hydro can fluctuate it’s power output from the John Hart generating station to take advantage of the wider electricity market and to meet varying domestic electricity demands. This operational flexibility was an element of the consensus water use plan that was developed with the community, and that BC Hydro has been operating to since January 2013. From January to mid-February, flow rates below the generating station can range from about 80 m3/s to about 120 m3/s and can fluctuate between those ranges within an hour. “For public safety, particularly for fishers in the river, please be cautious during this period when river flows can unexpectedly fluctuate within this range,” Watson said. “While BC Hydro has the flexibility to vary flows, John Hart is mainly an important regional source of power and not a preferred source of generation flexibility within the provincial BC Hydro system. It is therefore done to a limited degree.” This operation does not impact fish habitat as the river area is covered with water at flow rates greater than 80 m3/s.