B.C. drought brings increased flood risks, far-reaching damage, experts warn | CBC News

As severe drought conditions have helped usher in British Columbia’s most devastating wildfire season on record, experts and elected officials are warning of increased flooding risks and lingering damage even after wetter weather returns.

More than 80 per cent of B.C.’s water basins are experiencing Level 4 or 5 drought conditions, meaning ecological and economic damage are likely or almost certain, according to the province and environmental experts.

“We have groundwater levels dropping dramatically. We have river levels that are very, very low,” said Tom Pypker, chair of the department of natural resource sciences at Thompson Rivers University.

“This has implications for farmers who need to extract water to irrigate their crops. This has implications for cities that need to draw water out of these surface water bodies to supply their population.”

Without an end in sight to dry conditions, the province says it’s impossible to predict the extent of the “long-reaching” damage to wildlife, land and livelihoods.

“It is unlike any kind of drought conditions the province has ever faced and, in my opinion, truly is a sleeping giant of a natural disaster that we are challenged with right now,” Emergency Preparedness Minister Bowinn Ma said on Thursday.

“The impacts will be very, very real.”

Experts say climate change is a key driver of historic dry conditions, setting records for the driest summers many B.C. communities have ever seen, according to Environment Canada.

And the B.C. Wildfire Service says wildfires have burned more than 22,000 square kilometres of land across B.C. since April 1.

“These numbers are astronomical,” said Ma. “It has been a relentless fire season, which has been compounded by severe drought and the impacts of climate change.”

Drought and fires a ‘double whammy’

The concurrent drought and unprecedented fire season are exacerbating one another and leaving the province increasingly vulnerable to severe flooding, according to experts.

“It’s a double whammy effect,” said Younes Alila, a forestry professor at the University of British Columbia.

Drought kills vegetation and leaves soil exposed and hardened, Pypker said, with no root systems to help the soil absorb water when rain does fall.

Those trees and vegetation are easily uprooted and can be dangerous if they fall near people, homes or on power lines, said Pypker, adding that they can be carried away by heavy rains, turning into debris that can clog water systems and cause unexpected flooding. 

And when fires do burn, they capitalize on drought conditions and dried plants as fuel, leaving parched soil even more water-repellent than before.

When it eventually rains “in areas that have exposed soil, either due to drought or forest fires, which are basically the result of the drought, we may wind up with increased flooding,” Pypker said.

That’s what happened in 2021, when the deadly heat dome in late June and early July set off a drought that primed the Lower Mainland for catastrophic flooding when the atmospheric rivers hit later in the fall, according to Jonathan Boyd, a hydrologist at the B.C. River Forecast Centre.

It’s still too soon to say how much rain will come or whether another atmospheric river could cause flooding, but Boyd says “it can flip like a switch.”

Ma and Boyd say the best-case scenario is a prolonged, moderate amount of rain to gradually rehydrate soil without overwhelming damaged systems.

However, Pypker and Alila say it’s possible for the drought to stretch into the New Year if the majority of precipitation falls as snow at higher altitudes. 

Trees, wildlife under increased stress

The drought’s longer-term impacts remain to be seen, but it is already damaging and transforming ecosystems across B.C.

In Vancouver’s Stanley Park, nearly 25 per cent of the trees are dead and decaying due to several summers of drought that have prolonged a western hemlock looper moth infestation, according to the Vancouver Park Board.

The pests usually cause issues for just a year or two, but dry conditions have made trees more vulnerable to an infestation that is now in its fourth year. 

“In the recorded history of Stanley Park as we are aware, there’s no record of this amount of mortality,” said Joe McLeod, the board’s manager of urban forestry, fleet and strategic planning.

“I think eventually we’re going to see changes in the species composition in Stanley Park and because of the changes in heat and the drought conditions, we’re seeing a lot more stress.”

Depleting water levels are also endangering wildlife, including salmon that use waterways to return to their spawning grounds.

Low water levels can trap fish or slow their commutes, says Pypker, as well as lead to warmer water overall that doesn’t hold enough oxygen for them to breathe.

Last week, Fisheries and Oceans Canada found that “stressful environmental conditions” likely killed hundreds of salmon and trout in the Cowichan River in mid-July. 

In the Comox Valley, the Tsolum River has been below critical water levels since late July, the same conditions that killed several adult pink salmon in 2021 as oxygen levels depleted while they tried to make it through a bottleneck to spawn. 

Residents near the Arrow Lakes in B.C.’s West Kootenay region have raised similar concerns for the Kokanee salmon that spawn in the lakes and tributaries there.

Calls for coordinated drought strategy

The drought’s wide-ranging impacts on agriculture, wildlife and natural disaster risks have some communities and experts calling for more coordinated, drought-specific forestry and emergency planning.

Tofino, on Vancouver Island’s west coast, has received just over 100 millimetres of rain since May 1, about 75 per cent less than the usual 456 millimetres at this time of year, says Coun. Kat Thomas, prompting Stage 3 water restrictions. 

It’s been a wake-up call for the district to solidify its drought planning and water retention technology and strategies, she said. 

“Climate change is clearly affecting us worldwide. British Columbia has been bearing, obviously, the brunt of that, with droughts and wildfires,” Thomas said. “It is a reality that we are facing.”

Pypker says the province needs to have a coordinated drought strategy moving forward as climate change is melting glaciers that feed many of B.C.’s rivers long after the seasonal snowpack melts.

“In the near term people may see [drought] as sort of a passing weather phenomenon … but [we’re going to] start to see these consistently happening from year to year,” said Pypker.

“Water is a resource that we all recognize as a vital need and I think that’s how you start to raise the alarm bells that we need to have a strategy to deal with drought.”