What June’s heatwave means for the future of your tapwater

Photo by: Dru!/Flickr

If it wasn’t for climate change, June’s heatwave likely never would have happened. Scientists from around the world said the heatwave, which saw temperatures top more than 40 C in parts of the Fraser Valley, was extremely unlikely—“the statistical equivalent of really bad luck,” they said. But if global temperatures continue to increase, these kinds of heatwaves will transform from bad luck to routine events, happening as often as every 5 to 10 years. And that will challenge the complex systems that deliver water to hundreds of thousands of residents.

Although it may be hard to imagine in famously rainy BC, if more 40 C heatwaves are in our future, the valley’s existing water systems may not be enough.

In the five hottest days of the heatwave, Chilliwack residents used around 115 Olympic-sized swimming pools worth of water (nearly 288,000 cubic metres of water). At its peak, residents used nearly twice as much water as they did on the same day last year. Chilliwack wasn’t the only community to see significant increases. Abbotsford and Mission residents, who rely on the same water system, used nearly 238 swimming pools of water during the heatwave. Metro Vancouver also reached near-record levels, with 716 swimming pools of water taken from its reservoirs in one day.

Such high water demand is unprecedented, and residents around the region have been warned to limit their use. With climate change, water conservation will become even more important—particularly as more people move into the Fraser Valley. In Abbotsford and Mission, massive increases in water consumption in the mid-2000s left residents facing an impending water shortage. Abbotsford developed a plan to access water from Stave Lake, as well as from nearby Norrish Creek, but residents voted down the plan, forcing the city to focus on curtailing water consumption instead.

Abbotsford and Mission continue to get their drinking water primarily from Norrish Creek, which flows from Dickson Lake. But only so much water can leave the lake before it’s empty. Climate change and earlier snowmelts will make it harder for Norrish Creek to fulfil the region’s water demand, as the lake both fills and evaporates earlier.

The cities are now in the process of developing a new collector well system that would capture groundwater from near the Fraser River. The United Nations has applauded communities that have gone on well systems, saying “there is a growing recognition of groundwater’s relatively high resilience to climate change and climate variability.” But we still know relatively little about aquifers and how exactly climate change and increased use will impact them in the long term.

In Chilliwack, that is particularly important. Chilliwack’s water comes almost entirely from the Sardis-Vedder aquifer, an aquifer of sand and gravel just a few metres below the surface near the Vedder River. Like Abbotsford’s system, which needs to make sure Norrish Creek has enough water for fish downstream, Chilliwack also needs to monitor water use so groundwater streams have enough flow for the fish. (These include Peach Creek, Luckakuck Creek, and Atchelitz Creek, among others.)

A small number of days with extremely high water use, like June’s heatwave, likely won’t have much of an impact on streamflow. But a sustained increase could have significant consequences on the streams and the aquifer itself. Changes in precipitation could also have a significant impact—especially on how much water actually ends up in the aquifer. That, a study said, could be one of the first major impacts of climate change on local groundwater.

Although the province says enough water is still entering the Sardis-Vedder aquifer to meet the water needs of both people and fish, it is now at record low levels. An observation well at Mountainview Park near Evans Road showed that the water in the aquifer is now 3.3 metres below the surface—the lowest it has been in the last 10 Julys.

As Chilliwack continues to grow, it will need to find other water sources, just as Abbotsford and Mission are. Chilliwack’s 2040 Official Community Plan said it would consider expanding its water source as the population approaches 100,000 people (it was at 95,000 in 2020). Back in 2013, tests were being done on the Chilliwack-Rosedale aquifer, which is one of the next places municipal water would be sourced. David Blain, director of Chilliwack’s department of engineering, said the city is looking at developing a water source on that aquifer, and is currently waiting for provincial approval on 2 wells in the Eastern Hillsides area.