The Penticton portion of the Okanagan River channel was this dry in 2019. It may happen again in 2021 as the Valley moves into its latest drought season.

(STEVE ARSTAD / iNFOnews.ca)

Severe watering restrictions imposed in Summerland during the peak of last week’s heat wave may be a precursor of what’s to come for others as the Okanagan hits drought levels.

While that was a unique event, it may be duplicated as water levels continue to decline in Okanagan and Kalamalka lakes which are now at a Stage 3 drought level.

Summerland issued an appeal to residents last week to cut their water use by 30 per cent or face a lengthy boil water advisory because its water treatment plant could not keep up with demand during that record-setting heat wave.

The district municipality went so far as to cut off the water to about a dozen of its heaviest agricultural water users for a few hours in the middle of the night.

That worked. For now.

“We’re still up there in our usage but it looks like the danger zone is past,” Jeremy Storvold, acting director of works and infrastructure for Summerland, told iNFOnews.ca. “We're keeping an eye on it and we’re working with our heavy irrigation users. We are planning how they are using their water to keep it off our peak times.”

The City of Kelowna sent out an advisory during the peak of the heat wave asking people to be more cautious about their use of water.

“We’re contemplating moving to Stage 1 (water restrictions),” Andy Weremy, water operations manager for the City of Kelowna said. “We’re in the process of discussing and developing our communications strategy. It could come as early as next week.”

Stage 1 restrictions in Kelowna are mostly the existing rules that allow each home to only water three days a week year round. There would be a request to cut consumption by 10 per cent and not to do things like wash driveways and cars.

It’s not that Kelowna, or other valley water providers, are about to run out of water, any more than Summerland was.

It’s not unusual for the City of Kelowna to pump out 90 million litres of water a day during dry summer months, compared to 60-70 in the winter.

It pumped 107 million litres on July 2. While it has a capacity well above that (about 140 million litres), having to shift water into different areas of the city and running pumps more all cost money.

And, if water consumption is not restrained, it could mean tens of millions of dollars for new pumping stations as the population grows.

“You need to start changing attitudes and habits a long time before a plant is needed,” Weremy said.

That’s one of the reasons the Okanagan Basin Water Board drafted its Drought State Trigger Guidelines after the province declared what it called a Level 4 drought in 2015.

The report was completed in 2017 but no trigger has been pulled since then.

That’s likely to change this year.

The key trigger points are the levels of Okanagan and Kalamalka lakes.

Both lakes have just moved into a Stage 3 drought level. That’s not that far off the worst-case, Stage 4, level.

The low lake levels may trigger more watering restrictions, as suggested by Weremy for Kelowna as early as next week, but they won’t be universal and the water board can’t impose any restrictions.

“Just because the drought stage trigger may say the lake is in Stage 3 does not mean that the water purveyors will all move to Stage 3 (watering restrictions) immediately because they’re also looking at their demand, their infrastructure, whether or not they have alternate water sources so they could move off the lake to a different water source,” Kellie Garcia, policy and planning specialist for the Okanagan Basin Water Board, said.

Lake levels were studied over the years and it was decided that an Okanagan Lake level of about 342.6 metres or less was heading into drought territory, with four stages identified.

At 342.015 metres on July 5, Okanagan Lake was just into Stage 3 on the drought charts. Under 342.0 metres and it’s rated as Stage 4.

Full pool is considered to be 342.75 metres above sea level so there's only three-quarters of a metre difference between full and serious drought.

Kalamalka Lake was at 391.39 metres on July 5, putting it into Stage 3 as well.

Greater Vernon Water takes 45 per cent of the 24 billion litres of water it distributes every year from Kalamalka Lake. It services about 53,000 customers in Vernon, Coldstream and some rural areas.

The City of Penticton gets its water from Okanagan Lake and Penticton Creek, serving about 32,500 customers.

What these drought levels mean in terms of water restrictions will be different for each water supplier.

For example, Black Mountain Irrigation District, which provides water to 23,000 Kelowna residents, has high elevation water reservoirs that filled this year. A large amount of its water is drawn from Mission Creek.

Weremy said Black Mountain is reviewing its supplies and demands right now but that the Glenmore Irrigation District, which serves about 20,000 Kelowna residents and takes some of its water from Okanagan Lake, is considering matching what the city does in terms of watering restrictions.

Vernon has also issued a caution to its residents to reduce use and to expect further restrictions. Lake Country has actually moved into its Stage 1 level of water restrictions.

Even as the Valley moves into a drought situation – something that is likely to be an annual event –  cities are not going to start running out of water any time soon.

Weremy noted that Kelowna has four water intakes in Okanagan Lake, some of which are 50 metres or more deep, so they run no risk of drying up.

And most water systems in the Okanagan have similar back-up resources and can move it around from where it’s most plentiful to where it’s most needed.

“The thing that makes the Okanagan resilient and why we’ve been doing OK in these dry years is because a lot of the water suppliers have multiple sources of water,” Garcia said. “They have their reservoirs up in the highlands but they also have, maybe, a groundwater well or a lake source so they like to have redundancies in their systems.”

The problem is reservoirs, whether they be upper elevation lakes or large holding tanks on the tops of hills, need to be kept relatively full for things like firefighting.

Research done by the Okanagan Basin Water Board shows that some level of drought will be an annual event as summers become hotter and drier.

READ MORE: Battling floods and droughts in the Okanagan depends on more than a dam in Penticton

“There have been some studies that have shown that the amount of water that is drawn from the lake isn’t necessarily a large amount,” Garcia said. “If people cut back on the watering of their lawns, it’s not going to make a monstrous difference in that drought year. Where it will make a big difference is where we have multi-year droughts because, if the lake doesn’t refill for a year or two, then every drop counts at that point.”

The full report on drought triggers can be seen here.

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