Let the lawns go brown: Water conservation key for future Metro Vancouver droughts

A significant amount of the water in Metro Vancouver's complex reservoir system is consumed not by people, but by lawns, says Linda Parkinson, water services director for Metro Vancouver

Author of the article:Glenda Luymes
Published Dec 31, 2023 • Last updated Dec 31, 2023 •

Metro Vancouver’s annual water use peaked at 5 a.m. on a Saturday in midsummer.

Not an hour favoured for doing laundry or washing the car, most people were likely sleeping a few minutes after dawn on Canada Day.

But at that moment, more water was flowing from taps than at any other time during the high-demand season, likely due to lawn watering.

The timing of the “peak hour” — and other hours of high usage around 5 a.m. on weekends — reveal a general attitude about water that needs to shift as Metro Vancouver’s water system continues to be tested by climate change and a growing population.

It's not something we can take for granted,” said Linda Parkinson, water services director for Metro Vancouver. “We churn out the ‘we live in a rainforest’ line, but that’s really misleading.”

At the end of the high-demand season, Metro Vancouver’s water services department takes stock of how the region’s water system performed. The report, presented to the regional board, describes a year where snow melted early and fast, worsening a provincewide drought. At the same time, regional water demand soared.

On July 1, the region’s peak hour water use hit 1.96 billion litres per day, a measurement of flow rate. Consumption dropped as the day went on, but four days later, the region would record its peak day water use, with 1.56 billion litres used on Wednesday, July 5.

While the region’s water consumption is usually around 1 billion litres a day (BL/d) outside peak season May 1 to Oct. 15, demand climbs by about 50 per cent in summer. For 11 days in 2023, consumption was over 1.5 BL/d. A 2019 study attributes 38 per cent of that increase to lawn watering alone, with 31 per cent attributed to other watering and 21 per cent to seasonal indoor use, such as cooling.

“It all really pales in comparison to lawn watering,” said Parkinson.

Concerned about high demand and the effects of the continuing drought, Metro Vancouver banned lawn watering in early August, moving from Stage 1 water restrictions to Stage 2 for the first time since 2015.

A unique year

Parkinson said that while monitoring and projection work is done in the winter months, weather and demand, which are unique year to year, dictate the region’s operating strategy.

The goal is to start the high-demand season with the reservoirs at “full pool” in April. As the weather warms and demand starts to rise, reservoir levels are drawn down, but then filled again as the mountain snowpack begins to melt.

This past May, with temperatures about four degrees warmer than usual, the melt happened early and quickly and not all of the water could be captured. There was less rainfall in the spring to refill reservoirs — part of a drought that would affect most of the B.C. and lead to about half the normal amount of rain from May to the end of September in the Metro Vancouver watersheds.

“Once the snow has melted … we don’t have a lot of levers left to pull,” said Parkinson. “The only thing we can control is demand.”

So Metro Vancouver made the decision to move to Stage 2 watering restrictions in early August, banning lawn watering.

Like turning around a large ship, the new restrictions weren’t immediately noticeable, but by the end of the month, demand was falling, said Parkinson.

Consumption data shows that in May, June and July, the average daily water demand increased steadily from 1.23 BL/d to 1.35 BL/d to 1.46 BL/d.

After the restrictions came into effect, the average daily water demand slightly decreased to 1.33 BL/d in August, 1.17 BL/d in September, and 1.05 BL/d from Oct. 1 to 15.

Watching the numbers, Parkinson could still see the little telltale spike in water consumption between 4 and 5 a.m. on weekends, indicating some people across the region continued to water their lawns despite the ban. She believes it may have been automatic irrigation that was set up early in the year and not changed when the ban took effect.

It’s one of several lessons learned this year that could be reflected in next year’s operations.

Feedback from member municipalities also identified other areas that may need attention. For example, said Parkinson, enforcement officers reported difficulty distinguishing when someone was watering their shrubs or their lawn, with shrub watering still permitted.

“Do the shrubs actually need watering every day?” she asked. “That’s also something we could look at next year.”

Drinking water wasted on lawns

Parkinson said a significant amount of the water in Metro Vancouver’s complex reservoir system is consumed not by people, but by lawns.

In that, she sees an opportunity to improve the region’s water system.

Metro Vancouver’s water supply outlook predicts the region’s water needs could grow from the current 390 billion litres of water a year to between 500 to 600 billion litres by 2120.

Plans are already underway to double the capacity to draw water from Coquitlam Lake, the largest of the region’s three drinking water sources. Construction of a new water intake in a deeper part of the lake, a water supply tunnel, and water treatment facilities, is expected to begin in the late 2020s, with completion targeted for the late 2030s.

But the estimated $2.3-billion project is still a stopgap measure. By 2070, the region will be at risk of running out of water in moderate and high-demand scenarios.

A higher dam at Seymour Falls has been identified as the “most likely potential project” for long-term water supply, providing storage capacity for an additional 145 billion litres of water and eliminating forecast future shortages for at least a century.

But Parkinson said that along with securing another source, the region needs to work harder on conservation.

“The numbers are the numbers,” she said. “We use a lot of (water). We can’t say build more reservoirs, flood more valleys, when we use so much of it. We can’t really say we’ve done everything because our consumption is just too high.”

Heading into winter, Metro Vancouver is already planning for next year’s high-demand season, incorporating lessons learned in 2023.

Parkinson said she was heartened to see the growing public support for conservation.

“Ten years ago we might have had more pushback (on moving to Stage 2 restrictions),” she said.

Richmond Mayor Malcolm Brodie, chair of Metro Vancouver’s water committee, thanked residents and businesses for their efforts to conserve supply, which were successful.

“Our region has one of the highest per capita drinking water consumption rates in Canada, so we have work to do going forward when it comes to conservation,” he said.

“The climate is changing and becoming more unpredictable, and we need to use water responsibly all year long.”

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