The Comox Valley has come through the second driest October to December period in 39 years of precipitation data. However, the weather has turned wet, so BC Hydro needs to increase flows from the Comox Dam for flood risk management considerations.
Hydro is issuing a public safety advisory to be cautious around the Puntledge River Thursday, and to stay away from the river from Friday to Monday due to dangerous flows. Temporary caution signage has been posted along the river and will be updated Friday to danger signs.
“Through the fall we’ve been generating power at about 50-75 per cent of capacity,” a news release states. “The Comox Lake Reservoir has been around 133 to 134 metres, and annually generally fluctuates between about 131 to 135.3 metres.”
There was “modest precipitation” in the upper watershed on Tuesday. The temperatures have also been mild which may have caused some mid-elevation snowmelt. The resulting inflows into the reservoir has increased the reservoir level to 134.2 metres and rising.
“We are watching another significant storm system that looks to hit the watershed on Thursday and Friday. To better control the reservoir, at 6 p.m. Thursday, we will increase the Comox Dam discharge to around 50 m3/s. On Thursday night, discharges will be further increased, possibly up to 110 m3/s. The normal water release from the dam this time of year is about 32 m3/s.”
Water begins to free spill over the dam at 135.33 metres. The level may peak around 134.8 metres over the weekend.
“This is the season of the King Tides, though we are fortunately in the low end of the tides this week.”
The King Tides this month will be in place Jan. 10-17 and peak at 5.3 metres. The tide Thursday is 4.9 metres and trends down to 4.7 metres by Sunday. BC Hydro may lower flows from the dam for four hours during the high tides.
At this time we see a low risk of isolated downstream flooding.
The weather next week looks to be cooler and drier.
2019 was a dry year and this is the first time this fall/winter that we are releasing extra water for flood risk management.