Last year, as the Oldman Reservoir dropped to a level not seen since 2001, the Municipal District of Pincher Creek was forced to take action.
Water levels dropped so low that the M.D.'s intakes within the reservoir — which sit above the historic bed of the Crowsnest River — were exposed. They could no longer draw water.
The M.D. was forced to haul water into the community on trucks, at a cost of roughly $7,500 per day.
Eventually, the municipal district amended a temporary water licence to pump water near its existing intakes. And while the M.D. is still hauling potable water daily, the set-up covers about 75 per cent of its water and saves about $3,000 a day.
As Alberta stares down the possibility of a severe drought, Pincher Creek may not be alone this year in adapting to unforeseen challenges tied to water access.
The Oldman reservoir outflow at the Oldman dam is shown in this photo dated Aug. 18, 2023. (Government of Alberta) With such conditions looming, Alberta Environment Minister Rebecca Schulz said irrigation districts have raised the possibility of "interbasin diversion" often in recent months — referring to the transfer of water from one major river basin to another.
"It's one of the ideas that's been brought forward in terms of one of the ways we can meet those needs, especially in southern Alberta, with water from other basins. This is something we could look at," she said March 13.
More than 80 per cent of Alberta's water supply is found in the northern half of the province, but 80 per cent of the province's demand is in the south.
Water diversion — redirecting water for various purposes, whether they be municipal, industrial or otherwise — takes place often within sub-basins in the province (the South Saskatchewan River Basin, for example, contains four sub-basins).
For instance, the Lethbridge Northern Irrigation District and the St. Mary River Irrigation District have very large diversions out of the river into the main canal system, noted Shannon Frank, executive director of the Oldman Watershed Council.
Interbasin diversions, on the other hand, are rare. But such ideas are often raised in times of drought, Frank said.
"That is something we hear occasionally, people saying, 'Well, why can't we build a pipeline from a bigger river? Like, the North [Saskatchewan] or the Athabasca? These are huge, much larger rivers than we have,'" Frank said. "Realistically, a big part of the reason is cost."
A small number of interbasin diversions have occurred in Alberta, but the province noted in an email to CBC News that such projects have been done on a local basis only and have been limited to emergencies.
No matter how much water is involved, transfers have to be approved by the legislature by passing a special act to authorize the licence, according to Alberta's Water Act.
Such diversions bring with them various concerns tied to water chemistry, invasive species and Alberta's water allocation commitments with surrounding jurisdictions.
Significant demands on water in the south
To understand why such an idea is on the table, consider the South Saskatchewan River Basin (SSRB). The Bow, Oldman and South Saskatchewan sub-basins located within the SSRB have all been closed to new surface water allocations since 2006.
The SSRB flows across the Alberta-Saskatchewan border and serves the water needs of four large Alberta cities: Red Deer, Calgary, Lethbridge and Medicine Hat. Population and economic growth means increased demand on an already-taxed water supply.
And those growing population centres raise concerns for people like David Cox, reeve of the Municipal District of Pincher Creek.
"I think we could probably outpace our supply. And I don't think that's the short-term. But when you get a drought like this, it gives you a real reality check," Cox said.
Irrigation is a major user of the province's water supply. Alberta has the largest irrigated area in Canada, reaching about 690,000 hectares in the province. Of that, 566,000 hectares are in southern Alberta along the SSRB.
Four sub-basins make up the SSRB, three of which are the subject of what the provincial government has called "unprecedented" water-sharing negotiations. Results from those negotiations were due to wrap up at the end of March. That deadline was extended to mid-April by Schulz last week.
This map shows Alberta's 11 irrigation districts, located in the South Saskatchewan River Basin. (CBC) Given the demands on the province's water supply in the south, the idea of interbasin diversion could be on the table, said Tricia Stadnyk, a professor and Canada Research Chair in hydrologic modelling with the University of Calgary's Schulich School of Engineering.
"If we look at drought as a scenario that is going to become more common in this province and across the Canadian Prairies, then what do we do as a long-term mitigation measure?" Stadnyk said.
"When we start talking about diversion, of course, more permanent solutions start to rise to the surface in terms of things to consider. And that becomes very tricky for a number of reasons … I really caution Alberta to do its due diligence."
Water chemistry, invasive species, water sharing
In such a scenario, it would be important to keep in mind that such diversions change the water type, because the water source is changed.
"The specific water chemistry has a lot to do with the ecology that is supported by that watershed, and that water system," Stadnyk said.
"Right down from the temperature of the water that affects the ability of fish to spawn, to the aquatic biota that can live within that water because of sensitivities to pH and other aspects of water quality."
It also becomes a big issue for invasive species, something that has been seen across the Great Lakes and other jurisdictions, Stadnyk said.
She cited diversions that took place upstream of Lake Winnipeg that, in addition to equipment and boats being transported from and to different waterways, likely led to the introduction of zebra mussels into the large Manitoba lake.
"That's really tragic … [it] had remained, up until a few years ago, unimpacted significantly by zebra mussels," she said. "Once you have them, they're incredibly difficult to get rid of."
Zebra mussels are considered a significant threat to Alberta's aquatic ecosystems but aren't currently found in the province, according to the provincial government. If a mussel infestation took place in the province, the government estimates a total cost of $75 million annually to protect and replace water-operated infrastructure.
In Alberta, the concern would more likely be the spread of whirling disease, according to Stadnyk. The disease is caused by a parasite that affects fish, and in particular trout. It affects the nervous system, causing them to spin in a distinctive "whirling" behaviour. The mortality rate of young fish with the disease is up to 90 per cent.
This rainbow trout displays the characteristic black tail and skeletal deformities indicative of whirling disease. (Stephen Atkinson/Oregon State University) Stadnyk said in the scenario of interbasin diversion, it also would be important to be cognizant of drought conditions that are developing in the north.
"We want to be careful not to put another system into a state of crisis just for the sake of supporting a system further south," she said.
With irrigation districts often raising interbasin diversions as a possible option, Schulz said during her March 13 news conference that the province would need to ensure it was keeping such matters in mind.
"We'd want to, obviously, I think do our work to make sure that we're not impacting the current allocation commitments that we have in terms of the flow-through of water that we're expected to pass through, whether that be to Saskatchewan, to the Northwest Territories or to Montana. So that would be one of the things we'd have to look at," she said.
Alberta Environment Minister Rebecca Schulz said March 13 that while the subject of interbasin diversions had come up often as part of recent negotiations, it would need to be considered carefully. (CBC) Schulz said the other thing to consider would be impacts to aquatic life, including effects on the species that live in those basins.
"But it is something that is raised, it's been raised on both of the tele-townhalls that we've had, as one of the solutions," Schulz said.
"More work needs to be done on that before we could say what that might look like, but it is something that has been raised, quite a bit I would say, often the last weeks and months."
In a statement sent to CBC News, Ryan Fournier, a spokesperson to Schulz, wrote that a number of environmental, economic and social factors would need to be considered before expanding the use of interbasin transfers.
"This includes impacts to local communities, environmental impact of water and biodiversity being moved, and the costs/feasibility of creating infrastructure to enable such a transfer," Fournier wrote.
"We will be taking a hard look at all options, including interbasin transfers, to maximize our water supply in the years ahead."