$4B irrigation project must be carefully studied

Impacts are many and complex, Sarath Peiris says

The Saskatchewan government is going back to the future by resurrecting an irrigation scheme that was shelved a half-century ago, with plans to more than double the irrigated farm acreage over the next decade at a whopping cost of about $4 billion — the largest single project in provincial history.

Certainly, the attraction of tapping the full potential of the massive Lake Diefenbaker to ensure water and food security for Saskatchewan is undeniable, especially in an era when the need to mitigate impacts of climate change is clearly evident.

Although the proposed project has wide support from Saskatchewan’s agriculture leaders and politicians who point to this investment returning major dividends of GDP growth, job creation and value-added industries, this development involves far more than simply irrigating 500,000 acres of farmland in west-central and southern Saskatchewan.

John Pomeroy, director of the Global Water Futures (GWF) program, says large-scale modelling shows warmer weather and more winter snow and rain actually increasing the flow of the South Saskatchewan River. However, peak flows will arrive in March or April by the end of the century, instead of the current June or July.

It could create problems in Alberta, with a large number of irrigation farmers for whom the peak flows will come too soon, Pomeroy said in an interview. “So, there will be a lot of demand and interest in building more dams and increasing the size of reservoirs in Alberta, which could impact irrigation in Saskatchewan.”

Saskatchewan itself will get wetter with climate change, he said. However, the weather will be highly variable, with drought years that make irrigation necessary and wet years when it’s pointless, Pomeroy said.

With an estimated cost between $550 and $950 per acre for pivots and related equipment, convincing dryland farmers — many nearing retirement — to convert to irrigation and invest what could be $600,000 per section might not yield the hoped-for results, either.

“So, the economics of the project have to be looked at very carefully. Further, the water that is taken out for irrigation means it is out of the hydrological system in the ground. That means it’s not in Lake Diefenbaker to produce hydroelectricity. The more we irrigate, the less hydro energy we get.”

The impact will be felt downstream as well, affecting hydro power generation to the north as well as in Manitoba.

“This project cannot only be about irrigation. It needs to look into impacts on downstream Indigenous communities, and into assuring a clean, reliable water supply for Saskatoon in the future. And because it relies on water from Alberta and impacts water in Manitoba, there’s a national interest in this,” he said.

Taking more water from the flow will further affect the Saskatchewan River delta around Cumberland House, where residents who rely on it for trapping and tourism are already feeling the impacts of ecosystem changes from previous projects.

Pesticides and nutrients used in farming degrade any water that returns to the river, as does runoff from livestock operations.

Pomeroy is a leading expert in hydrological processes and modelling in prairie environments. Other scientists at GWF are similarly highly qualified to offer advice on the social, economic and hydrological impacts of expanding irrigation, but Pomeroy said they didn’t hear from the province about the latest iteration of the plan.

For instance, although the announcement refers to Phase 3 build-out of the Qu’appelle South irrigation project providing a secure water supply for Moose Jaw and Regina, modelling by GWF researcher Karl-erich Lindenschmidt shows that even doubling the water volume from Diefenbaker via the Qu’appelle River channel does not improve water quality of Buffalo Pound Lake. If it’s done through the proposed upland canal, Buffalo Pound quality would improve slightly, providing nutrient runoff doesn’t increase significantly.

“We can do this, but we have to be careful. It’s going to take advanced scientific background and top-notch engineering to get it right,” said Pomeroy.

“This is not just a Saskatchewan development. It’s a national water development, so there needs to be federal oversight with respect to Indigenous communities and interest of other provinces to ensure that it’s a viable project in the future.”

Given Saskatchewan’s history with political megaprojects, Pomeroy’s cautions deserve close attention.