While it isn’t front of mind given recent and impending rains and flooding, experts say we should be more concerned about future droughts, which are projected to get worse.
Water levels on Sooke Lake reservoir dipped well below the five-year average during the summer 2021 drought, according to Capital Regional District statistics. Bethany Coulthard, a hydroclimatologist and watershed ecology expert doing research at the University of Nevada, Las Vegas – she lives and works in Shawinigan Lake – said these conditions could tip the balance in the long term.
“(This year) is a great case in point of why summer and winter are kind of independently important. You could say they’re the two main factors that are controlling water supply for Greater Victoria,” she said.
Sooke Lake Reservoir, which has refilled to almost capacity in November– more than a month earlier than normal – tends to fill up in winter and is depleted over summer, Coulthard said.
But this past summer’s heat dome tipped the balance, the hotter conditions depleting the reservoir faster than usual. Add to that the higher demand for water in summer and Greater Victoria’s growing population and future water shortages are likely, she said.
“I’ve talked to people down in Nevada and the idea that you could have a drought like we had this summer followed by major flooding in the same year is completely beyond them. It’s such a unique system,” Coulthard said. “But what we’re seeing now is what climate scientists have been saying for decades – the extremes will become more extreme.”
In theory, expanding the Sooke Lake reservoir could solve concerns about drinking water supply, if we keep seeing heavier rainfalls in the winter, she said. The reservoir was officially at 100 per cent capacity early this week, reaching that point far earlier than normal. Excess water will spill out into the Sooke River.
The reservoir opened in 1915 and was last expanded in 2002, when the dam was raised. There are long-term plans to develop the Leech Water Supply Area, which would expand the CRD’s water supply, according to a CRD spokesperson.
While the water supply issue could be a relatively easy fix, Coulthard said, harder to deal with will be the other impacts of drought, such as forest fires, higher tree mortality and wildlife habitat loss.
Impacts being seen now may only worsen, she said, as climate change continues to exacerbate conditions, but there is evidence that droughts have been worse in past, before the impacts of climate change.
During her PhD studies at the University of Victoria, Coulthard studied tree rings, which can give information about climate and the conditions at the time.
“It means the natural worst-case scenario drought, in our watersheds, is worse than what we thought,” she said. “Once you put climate change on top of that, as well as deforestation and increased population supply and demand, we’re set up for droughts to occur that are worse than any in the instrumental record.”