Public Works department reports on water supply strategy meant to supplement city plan

Chris Bush
Jun. 20, 2023

If Nanaimo had to replace its water supply infrastructure it would cost $1.5 billion.
That’s the figure Bill Sims, general manager of engineering and public works, quoted when he introduced a report on the City of Nanaimo’s water supply strategy at a governance and priorities committee meeting June 12.
The strategy is a supporting document to the Nanaimo Reimagined city plan, meant to guide the city’s water supply development over the next 50 years.The public works department is planning as far ahead as 2061 to determine how the demand for water will be met as the city’s population is projected to grow to 142,000 to 173,000 people. The city must meet that demand while also protecting the environment, maintaining aging infrastructure such as the 90-year-old South Forks Dam, and building resilience in the system to counter climate change.
Nanaimo is continually upgrading its water supply infrastructure – the South Fork Water Treatment Plant was built in 2015 and the midtown water supply project is currently underway – while preparing for a potentially drier future. Universal water metering came into effect in the 1990s and tiered rate increase billing and staged water restrictions were added in the early 2000s, measures that helped lower Nanaimo’s water consumption in spite of population growth.
“In the early ’80s and ’90s, water [demand] was very linear. We grew, so did our water demand,” said Mike Squire, city water resources manager, at the meeting. “Our water consumption per capita is going down. We’re actually using the same amount of water as we used in the mid 1990s with a population of 30,000 more. That’s very important when we’re projecting looking into the future.”
Squire said Nanaimo, at 190 litres per capita per day consumption in 2022, is ahead of its long-range targets for limiting water use. Nanaimo’s current per capita water consumption is already considerably lower than the national average of 251 litres per day and B.C.’s average of 353 litres of water per person per day. Consultants, he said, estimated that Nanaimo could continue decreasing consumption at a rate of five per cent per decade out to 2061.
But does Nanaimo have enough water catchment and storage capacity to compensate for climate change?
Squire said the city’s primary catchment watershed covers 52 square kilometres, which feeds the Jump Lake Dam reservoir that stores about 17 million cubic metres of water.
“That’s enough to supply the city for one year … We also have to look at environmental flow needs and they’re almost double what the city actually consumes from the watershed,” Squire said. “We’ve looked at all the yields, all the demands from the watershed and projected that forward. The big unknown for that too was climate change – what we need to do. All models predict longer, drier summers, which we’re in right now … and very intense precipitation during the winter.”
Nanaimo’s system doesn’t have the capacity to store such large short-period winter precipitation volumes for later use in the dry months and the storage system reserves 30 per cent of its capacity for emergencies and extreme drought conditions. However, it tries to avoid dipping into those reserves to ensure enough water is available for the following year. Squire said water use projections, based on 50 years of historical data and estimates of population growth, suggest extending Stage 3 water conservation should prevent the need to tap into water reserves.
Squire, asked by Coun. Ben Geselbracht about the climate change scenarios used to make the predictions, said they were based on a “high global emissions scenario” predicting an average global warming of 3.5 to 5.4 C by 2090.
Why not just increase reservoir capacity?
“What the consultants found was, if we did increase the reservoir size, there are drought years that the reservoir wouldn’t fill because we just do not receive that precipitation – it could be back-to-back drought years,” Squire said. “And there is sufficient size in [Jump Creek Reservoir] right now to sustain both drought conditions with climate change, while providing environmental flows for the next 20 years.”
The water supply strategy also suggests city growth scenarios will not have a notable effect on water storage requirements, but its recommendations include adding a secondary water intake and conducting seismic upgrades to the South Fork Dam. Construction isn’t likely to happen until at least 2030, according to staff.

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https://www.nanaimobulletin.com/news/report-suggest-nanaimo-will-be-water-resilient-for-decades/