BC Hydro will increase the discharge from Comox Dam by more than twofold Friday night through early Monday morning to control the Comox Lake Reservoir level.
BC Hydro advises the public to stay away from the Puntledge River from Saturday through Sunday.
The storms over the past weekend through Monday increased the reservoir level by almost one metre, Hydro said Thursday morning in a news release. In response, on Monday evening, BC Hydro increased the water discharge from the dam near the threshold where public river safety notification is required.
The standard water discharge below the dam for this time of year is around 32 cubic metres per second (m3/s) to allow full power generation and required fish flows, but was increased to over 40 m3/s on Monday and this weekend will be around 105 m3/s.
BC Hydro will then bring down the Puntledge River flow to the 45 m3/s level or lower after the weekend.
The weekend water release is intended for flood risk management but will also provide ideal conditions for the Vancouver Island Whitewater Paddling Society. If you are not a member of this society, you should not enter the river.
The reservoir has been slowly rising this week and was at 133.75 metres Thursday morning, and will continue to rise with Thursday’s storm.
However, with the water release this weekend the level may move down near the 133.5 metre level by early Monday morning. The reservoir is considered full and free-spills over the dam at 135.3 metres.
This is the first significant water release from Comox Dam for flood risk management this fall and winter storm season. There is no risk of downstream flooding.
BC Hydro tries to maintain water storage room within the reservoir to absorb water inflows from storm events, and releases water downstream in consideration of downstream river flows and ocean tides. The storms this week have been moderate in strength though combined, this past Friday evening through early Monday, 180 millimetres of rain fell in the upper Puntledge watershed.
BC Hydro can absorb high inflows as downstream rivers peak and then, as they subside, BC Hydro can release water to limit potential downstream flooding. Although BC Hydro’s dam and operations are unable to eliminate the possibility of flooding, it can reduce the frequency, size, and impact of such events.
— BC Hydro