Near record snow pack conditions have forced BC Hydro to obtain permission to operate John Hart Generating Station at full capacity all summer long.
Hydro had received a variance from the Comptroller of Water Rights in February to exceed its licence until April but that date was recently extended to try and prevent reservoir impacts and discharging high levels of water down the Campbell River during the peak summer recreation fishery.
“Little has changed since February and in fact the forecast has increased slightly with the near-record snow pack conditions,” said Stephen Watson, BC Hydro spokesperson. “The Upper Wolf River weather station is showing a snow melt to water equivalent of about 2,270 millimetres.
“This is about 165 per cent above normal and the second largest on record. An average snow pack year is about 1,350 mm water equivalent.”
BC Hydro considers the annual snow pack, along with about 50 years of inflow data, to forecast potential inflows into the Campbell River watershed. The Water Supply Forecast indicates the April to September runoff volume to be about 125 per cent of normal with a variance of about 15 per cent should it turn dry or wet.
That forecast will be updated by BC Hydro around May 9 to reflect the latest basin snow conditions but it is expected to stay well above normal.
The snow pack historically peaks at this time of year, and then begins to slowly melt until depleted around the end of July. BC Hydro has been generating power at John Hart at full capacity since February to create extra room in the reservoir.
The Upper Campbell Reservoir/Buttle Lake is currently at 214.15 metres and drafting. It has been steadily declining since February when it was near full at 219.5 m.
With the high water abundance forecast, Upper Campbell Reservoir/Buttle Lake and Lower Campbell Reservoir should hit reservoir recreation target levels for July and August, said Watson.
“The challenge for BC Hydro is under some water inflow modelling scenarios,” he said. “The Upper Campbell Reservoir could exceed 220 m by several metres and inundate recreation sites and incur shoreline erosion. River recreation, and particularly fishing, peaks in August to September with the pink salmon run. BC Hydro plans to operate John Hart at full capacity – at 118 Mega Watts given its age and operating thresholds from its original 126 MW capacity – or about 120 cubic metres per second (m3/s).”
That operating level may take place up to July 4 when BC Hydro’s planned annual maintenance of the generating units will begin. With one of the three pipelines from the John Hart Reservoir always off-line, discharge levels will be reduced to about 80 m3/s, which is the level where the river is fully covered with water and fishing access is still challenging.
River flows will slowly decline at the end of July but potentially stay at around 50 m3/s through mid-September. The water licence river flow targets in August are around 30-40m3/s.
Given the water supply forecast, BC Hydro has not operated the Salmon and Quinsam Diversions that can divert water into the Lower Campbell Reservoir, said Watson.
“The spring and summer temperatures, rate of the snow melt, and rainfall amounts are large unknowns,” said Watson. “For the fifth consecutive year this a far from average water supply year and BC Hydro will modify its operations as these challenging conditions develop over the next few months.
“BC Hydro will continue to inform the community of any significant operational changes as it balances all water use interests.”