Outflows from the John Hart Generating Station have reached levels not seen since mid-April due to a series of moderate to heavy storms that began hitting the Campbell River watershed on Tuesday.
Today’s storm has been heavy and the forecasted Saturday-Sunday storm may be heavier still in terms of rainfall, BC Hydro spokesperson Stephen Watson said today and, in the longer range forecast for next week, there is potential for a couple more substantial storms, lasting into Wednesday.
Since Tuesday, over 150 mm of rain has fallen in parts of the upper Campbell River watershed. Cumulative precipitation across the watershed from now through next Wednesday is forecasted to add 100 to 400 mm to that total. The freezing level is currently around 1,600 m for the current storms and will briefly drop tomorrow before potentially rising to 2,000 m early next week.
On Tuesday, the Upper Campbell Reservoir/Buttle Lake was at the bottom of its preferred operating zone, so it was well positioned to accommodate these storms. It is currently at 216.9 metres, up from 216.6 m at midnight, and continuing to rise. Throughout the year, the reservoir can normally fluctuate between 212 metres and 220.5 metres. During this time of year, storm season, Hydro likes to keep the reservoir below 219 metres so there is storage room and flexibility to absorb water inflows for downstream flood risk management considerations.
The current water inflow rate into the Upper Campbell Reservoir/Buttle Lake is about 600 m3/s. That’s the equivalent of an Olympic-sized swimming pool entering the reservoir every four seconds.
BC Hydro’s water discharge through the system and below the John Hart generating station was increased yesterday to full output: about 125 m3/s including spill. The last time the John Hart station was at full output was in mid-April.
Depending on a number of factors including total precipitation, freezing levels, potential for low elevation snowmelt during the storms, and quantity of runoff actually flowing into the three reservoirs on the Campbell River, BC Hydro may need to spill various amounts of water down Elk Falls Canyon for flood risk management. The canyon flow will increase tonight from 4 m3/s to 40-80 m3/s. By tonight, the total Campbell River flow below the generating station will be between 160-200 m3/s.
BC Hydro is forecasting daily average inflows into the reservoirs to be between 230 and 600 m3/s through the middle of next week. Much of that water will be stored in the reservoir.
The public is asked to stay away from the Campbell River above Elk Falls during this period of increased spill. In addition, people should be cautious around the riverbanks of the Campbell River this weekend and into next week and beyond. Safety warning signage will be going up at Elk Falls.
This will be the first time, since the Elk Falls Suspension Bridge was opened in May, that BC Hydro has spilled water down the canyon for flood risk management. This will certainly be an attraction but people are asked to view the falls from the safety of the suspension bridge and lookout.
BC Hydro’s operations are subject to change based on actual water inflow rates from these storms and changing weather forecasts. This active storm pattern looks to continue into the middle of next week.