It may seem Saskatchewan has an unlimited water supply, but the author of a new global study says that's not true.

On Tuesday, the World Resources Institute released a study of global "water risk," with its finding that one quarter of the world's population is under "extreme water stress" and that parts of Saskatchewan are at high risk of water stress.

Regions using more than 80 per cent of annual water supply are deemed to be at the highest risk. A colour scale on a world map uses light yellow, indicating low risk, to dark red, indicating high risk.

The situation looks bleak in the Sahara Desert, Australia, the Middle East and Southwestern United States.

Dark red spots also cover parts of Saskatchewan, including areas in and around Saskatoon and Regina. The high risk zones extend southeast to Estevan and Oxbow, and also west to the Lloydminster, Kindersley and Kerrobert areas.

The World Resources Institute has compiled more than 50 years of data. The regions with the highest risk of future water shortages are highlighted in dark red. (World Resource Institute)

"I think it's important to put these things on a map, assign a dark red colour to them, and have people act before it's too late," Hofste said in an interview from his office in Amsterdam.

"You are in a high water stress region. It means that when a drought strikes, or an extreme weather event happens …there is a high chance of running out of water. There won't be enough water in the taps for houses, for irrigated farms or for industry."

Hofste said there are several causes leading to Saskatchewan's water risk.

Agriculture, especially raising livestock, uses a tremendous amount of water. Invaluable wetlands are often drained to make way for these farms, he said.

Mining and oil and gas extraction is also a big water user. Some of these operations use tens of millions of cubic litres of water per year, he said.

Rutger Hofste compiled the data for the World Resources Institute study of global water risk. (Rutger Hofste)

Residential and industrial water use in our cities and towns is often inefficient as well, he said.

Water use is one half of the equation but the other half of the story is the province's water supply.

Hofste said climate change could lead to some flooding, but more often, it will cause prolonged dry or hot spells. Slowing down climate change remains an important goal, he said.

Picture not that rosy, says hydrologist

University of Saskatchewan hydrologist Jay Famiglietti said Saskatchewan could also face decreasing flows coming down from the Rocky Mountains into the Saskatchewan River and other water bodies.

"I think when we see studies like this, we realize that the picture is not as rosy as we thought it was. We have to pay careful attention to them as we think about how to manage our resources," said Famiglietti, director of the U of S Global Institute for Water Security.

Jay Famiglietti, executive director of the U of S Global Institute for Water Security, says a recent global study shows parts of Saskatchewan are among those at risk of a future water shortage. (Jason Warick/CBC)

Famiglietti said individuals, companies and governments need to work together to use water more efficiently.

Unlike forests or crops or potash, water resources flow from one province to another.

"Decisions that are made in Calgary impact what's happening in Saskatoon and in Saskatchewan," Famiglietti said.

"Likewise, what we do here impacts what happens downstream in Manitoba."

Some countries are increasing the rates they charge for water, especially for industrial operations.

Famiglietti said all the efficiency and cooperation in the world may not be enough.

He expects there will have to be some tough conversations in Saskatchewan and globally, about whether high water use activities are appropriate in certain regions anymore.