Low water levels could force Puntledge generating station shutdown

Puntledge generating station

Puntledge generating station

BC Hydro may need to shut down its Puntledge River generating station early this summer due to low water levels, according to Hydro’s Stephen Watson.

“We may have to shut down the generating station in July because we want to try to conserve as much water as we can for that September/October period,” says Watson, adding the situation could change if the weather changes. “In dry years we have shut down generation but it’s not that common, and it’s fairly rare to do it in July.”

Comox Valley Regional District senior manager of engineering services Marc Rutten adds water restrictions are heightened for areas serviced by Comox Lake, (Courtenay, Comox, and five nearby local service areas), when Hydro shuts down its generating station.

“We have a back-up pump station that we (use to) pump water from the river during times when BC Hydro takes their generator out of service,” explains Rutten. “And at those times our capacity to feed the system is extremely limited so we go to Stage 3.”

Stage 3 restrictions mean watering lawns, washing vehicles and filling swimming pools, hot tubs and garden ponds is not allowed at any time. Watering vegetables, flowers and shrubs is restricted to early morning and late evening and must be done with a hand-held container or hand-held hose. To view the water conservation bylaw, visit www.comoxvalleyrd.ca

BC Hydro recently shut down the generating station for maintenance work, causing Stage 3 water restrictions which ended Tuesday. Maintenance work is generally done twice per year in the spring and fall, according to Watson.

However, usually in June water levels are much higher, according to Watson.

“Right now, we’re seeing water inflows into the Comox Lake reservoir — in the last 50 years, there’s only five years where the water flows have been lower (at this time of year),” says Watson, noting the reservoir is considered full at 135 metres; it’s sitting at 134 metres now. “So, usually in June we’re getting right in the middle of the snowmelt, and there’s usually a fair amount of water coming in, the reservoir is full, and in some cases we have to free-spill water because of the abundance.

“But this year, with a very low snowpack, we’ve been really in water conservation mode going back to this past winter.

“The snowpack finished well below normal, and in fact it’s essentially depleted about six weeks earlier than average.”

Hydro normally runs its 24 megawatt generating station at 100 per cent at this time of year, but before the shutdown for maintenance, it was operating at 20 per cent.

As well, Watson notes tubers on the Puntledge may have noticed a decrease in water flows this year, as usual flows down the river at this time of year are 32 to 35 cubic metres per second, but they’re about half that.

Hydro applied last week for a water licence variance to lower the minimum river flow to 14 cubic metres per second rather than 16 cubic metres per second. Watson notes Hydro does apply for variances, but to apply this early in the year is a bit unusual.

“Typically we may get a variance in later July but usually you don’t get one in June,” he says, adding some years Hydro doesn’t apply for a variance at all. Hydro must conserve water now to ensure flows are high enough in the fall for returning salmon.

Rutten notes the CVRD Water Committee last week received a report for information outlining the status of the Comox Lake reservoir.

“It just kind of set the scene that … it’s kind of shaping up to be a dry, hot summer, with not a lot of snowpack and not a lot of water in the lake,” says Rutten.

“Right now, we are trying to gather as much information as we can and we’re trying to really understand the situation well, and then make the appropriate choices in the next few weeks or a month here, in terms of going to a higher stage. We haven’t actually announced that we will but I think we’re setting the stage to kind of let people know, let the directors know that there might be a need this summer to do that.”

Allan Coldwells, meteorologist with Environment Canada, says predicting precipitation for the summer is difficult, but this summer is looking to be drier than normal.

“We are thinking it will be a below-normal-precipitation summer, based on the patterns that are being predicted by our models,” says Coldwells. “We’re fairly certain the temperature will be slightly above normal, like one to two degrees, when you look at the period from May to September.

“Obviously, with such warm weather there’s going to be evaporation potential. There’s going to be obviously days that are hotter than others in that period as well. So, if you end up with more of those warmer days, mid- to upper-20s for example, then you’re going to have more evaporation potential.”

Coldwells adds precipitation levels for Comox have been fairly normal from January to May, (498.6mm with normal being 502.1mm). But, he points to the dry fall and early winter for low snowpack and low levels now in water basins.

“In October, we typically get 122.8mm at Comox; we only had 15mm. In November, we typically have 200.5mm, we only had 140mm and in December, we typically have 187.9mm, and we had 62.4mm.”



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