'The tap has been turned down': What Metro Vancouver's low snowpack means for the water supply
Given that we’ve already experienced record-breaking temperatures and water restrictions, you might not be surprised to learn that the Metro Vancouver snowpack is less than half of what it should be.
On May 8, the B.C.’s River Forecast Centre published its May 1 snow survey and water supply bulletin, showing that snowpack in the South Coast is 45 per cent of normal and 59 per cent of normal in the Lower Fraser, the two basins that Metro Vancouver sits in.
B.C.’s annual snow accumulation generally hits its peak levels in mid-April, and the May 1 snow bulletin gives an insight into the timing of the snow melt. Because most of April was warm and dry in much of B.C., snowmelt began earlier than normal at lower elevations.
“We’re seeing double-digit temperatures right to the mountaintop. So that means things are melting fairly quickly. I don’t want to say that it’s never happened before. We had very little snowpack in 2015 as well. But it’s certainly not normal,” said Heidi Walsh, Metro Vancouver’s director of watershed and environmental management for water services.
The bulletin adds that temperatures throughout April were above normal across the southern regions of B.C., with several locations — including Vancouver — recording monthly mean temperatures approximately 0.5°C to 1.5°C above normal.
In the first week of May, we saw temperatures spike far beyond seasonal norms, resulting in the “rapid melt” of snowpack.
B.C. River Forecast Centre/Supplied
Further, the seasonal outlook from Environment and Climate Change Canada points towards above-normal temperatures from May to July, especially in the coastal and southern B.C. areas.
“It’s challenging conditions this year, with a combination of low snowpack, we’ve had a really warm, dry April, and then the conditions predictions looking forward are for a hot, dry spring and summer. So all that put together, it’s definitely abnormal,” said Walsh.
How does this impact us?
Snowpack is important because it acts as water storage. Instead of rain, which immediately washes through the system, it stays up in the mountains, delaying the release of that water into the spring and summer.
Metro Vancouver has three water reservoirs that supply the region with water, one in Coquitlam and two in North Vancouver.
Walsh said that we can think about the reservoirs like “bathtubs” that get filled up with rain in the fall and winter. In the spring, normal water inflows and snowmelt both typically keep the reservoirs topped up.
“This year it’s like the tap has been turned down,” said Walsh. “Our snow melt is going to run out quite a bit earlier than normal.”
She said that if there’s a dry, hot spring and summer, we also won’t get the needed rainfall to top the reservoirs up.
Normally, snow melt happens in late June. But this year, Walsh said they are predicting it to end by mid-June, about three weeks to one month earlier than normal.
What can we do about it?
Hanna Hett/Daily Hive
In Metro Vancouver, average water use is about 1 billion litres per day. In the summer months, outdoor water use (through activities like lawn watering) balloons to a whopping 1.5 billion litres each day.
“If we go into that peak usage, it’s like the drains pulled wide open, and then we can have really quick drawdown at a reservoir,” Walsh said.
This is why the Metro Vancouver Regional District has already geared up. In a normal year, it limits residents and businesses to watering their lawns just once per week. This year, however, it moved straight into Stage 2 water restrictions, prohibiting lawn watering entirely, along with rules that you can’t fill aesthetic water features or wash surfaces like driveways or sidewalks.
“We can’t really control the snowpack, we can’t control the weather, but we can control how much water we’re using,” said Walsh.