Water scientists say an economic cost-benefit analysis is needed, and climate change must be taken into account
The plan to expand Saskatchewan’s irrigation capacity requires a water management plan for Lake Diefenbaker that addresses all the downstream concerns, say water experts.
John Pomeroy, who directs Global Water Futures, the world’s largest fresh-water research program, said the $4 billion project to add 500,000 irrigable acres is far more complex than simply taking more water out of the reservoir for agriculture.
“The amount stored in the lake is not relevant,” he said.
Lake Diefenbaker is used to produce hydroelectricity at several locations downstream — power generation is the primary economic benefit of the lake.
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The outflows along the South Saskatchewan River historically recharge the delta at Cumberland House, and then make their way into the Nelson River system through Manitoba, where they produce more electricity, and finally into Hudson Bay.
“Whenever we take water out for irrigation we’re taking it away from the ecosystem and we’re taking it away from downstream water supply and hydroelectricity development,” Pomeroy said.
He said if irrigation is expanded it has to be part of a redesign of how Gardiner Dam and Lake Diefenbaker are operated to maintain power generation and the ecological benefits particularly to First Nations downstream.
Pomeroy said rivers are supposed to flow to the oceans, not necessarily be captured.
There are tradeoffs and they have to be recognized, he said.
“To some degree (problems) can be mitigated through excellent design,” said Pomeroy.
After 2011 flooding downstream of the dam, the Water Security Agency asked Pomeroy to study dam operations.
“One of the major recommendations was that we develop operating rules for Gardiner Dam, which we currently don’t have,” he said.
“There are guidelines, but not operating rules that I think would help quite a bit in making sure we maximize the benefits to agriculture, to hydroelectricity, to downstream flooding and to downstream ecosystems.”
Pat Lloyd-Smith, a water and resource economist at the University of Saskatchewan’s college of agriculture, said managing the entire river system is key.
A project of this size should be coupled with efficient and equitable water management policy, he said.
“There’s a real opportunity for the province to have a robust water management policy that could alleviate concerns as well as ensure a more sustainable water supply in the future for all sectors — agricultural, municipal, industrial, environmental,” he said.
Both he and Pomeroy suggested the original attempt to develop irrigation around Lake Diefenbaker wasn’t successful because farmers have to buy in at significant cost.
“We can see some of the historical hesitation for adopting irrigation because it’s just such a radical change to your whole farming practice,” said Lloyd-Smith. “You’re moving from dryland, relatively low capital cost farming to irrigation where you have a high capital cost.”
It costs an estimated $160,000 per quarter to add the required infrastructure, according to Saskatchewan farmers who already irrigate.
Lloyd-Smith said the potential for net returns depends on what processing facilities can be attracted, and that’s risky.
He also said government might be looking for ways to recoup at least some of its investment and that could mean higher water charges for irrigators.
Others have suggested other areas and players will be more competitive than an agri-food industry set up in Saskatchewan.
Lloyd-Smith said it is a concern that a large investment “sets our ship in one direction.”
“I’m very intrigued to see the economic analysis the government has done,” he said.
So far, the government has released economic impact data but not a cost-benefit analysis.
Climate change is another issue that will affect how Lake Diefenbaker operates and whether irrigation will be a larger industry.
Pomeroy said Global Water Futures has calculated that while the western Canadian climate will warm it will also become much wetter, on average.
“You know in Saskatchewan, an average year can be drought and flood, so you have to be a little careful with averages, but the idea in general is there’d be more water,” he said. “That does open up discussion, what would you do with that water and certainly irrigation can be part of that answer.”
There will be years when the economic benefits will be modest and other years when they would be immense.
Although the lake was developed with agriculture in mind it has become an important factor in flood protection downstream.
Pomeroy said he worries that the amount of storage available won’t be enough for future variability in rainfall and snowmelt.
Lake Diefenbaker has been managed for both drought and flood protection but it’s difficult to get both functions out of a reservoir, he said. If it is managed for water supply then there are fewer options for flood control and vice versa.
Another factor to consider is that Alberta has been retaining more water in its reservoirs, causing March and April spring inflow to Lake Diefenbaker to drop by 50 percent since the early 1970s.
“One thing that we’re learning from climate science and some of the other water science is the future is not going to look like the past in terms of water availability, what droughts are going to look like, what’s flooding going to look like,” added Lloyd-Smith. “We might need to try to get ahead of some of these emerging water threats.”
