A University of Saskatchewan researcher says a form of oil extraction being encouraged by the Saskatchewan government needs more research and monitoring to avoid potential long-term contamination of drinking water in the province.

Grant Ferguson said his research suggests "waterflooding," a conventional form of oil extraction, could become a bigger problem for Saskatchewan than the more controversial practice known as fracking.

Waterflooding injects water underground to push oil and gas toward extraction wells. The researcher's fear is that water contaminated during extraction could seep into aquifers used by communities for drinking water.

"It might even be after that operator has gone out of business or the well has been decommissioned, and then finally those contaminants are going to show up at somebody's drinking water well," said Ferguson, a hydrologist and associate professor of geological engineering at the U of S.

Ferguson's research, completed in partnership with University of Arizona researcher Jennifer McIntosh, was recently published in the journal Groundwater.

Researchers say long-term effects unknown

Ferguson says the research explores how much water is being injected underground by petroleum industry activities, how it changes pressures and water movement underground, and how these practices could contaminate groundwater supplies.

The researchers concluded there is likely more water underground in "petroleum-bearing formations" where waterflooding has been used and that this has changed the behaviour of liquids underground.

Ferguson said the "bright side" of the controversy over the newer practice of hydraulic fracturing, known as fracking, is that it has led to an increase in research and knowledge about that practice.

The same research has not been done into the long-term effects of more conventional practices, such as waterflooding, he said.

In December, 2018, the province announced it was launching the Waterflood Development Program to encourage industry to build or convert existing wells into waterflood injection wells.

The program gives those who establish new waterflooding wells the option to defer the royalties they would pay to the province for three years in return for their investment.

Drinking water contamination 'highly unlikely': province

The Ministry of Energy and Resources said in a written statement its department has established maximum injections pressures to make sure injected water stays within the desired underground formation.

"The ministry monitors injection pressures and volumes, and will investigate if anomalies are noted or if an issue is reported," it said, adding that these types of operations have been conducted in Saskatchewan since the 1960s without contaminating groundwater.

It also said injection operations are usually done at depths well below groundwater formations. It said direct impact on a water source is "highly unlikely."

Ferguson said more research is needed to determine the long-term effects of the practice. He said waterflooding would be subject to more rigourous research and regulation if it was being introduced now.

"We just haven't tested these things enough," Ferguson said.

"It almost becomes like a forensic thing and I would hope that eventually we're getting ahead of the game rather than just trying to figure out what happened and what we shouldn't have done."

More monitoring needed, says researcher

Ferguson said the best approach would include increased monitoring and regulation of groundwater supplies by the Saskatchewan governmen and more detailed study on the long-term impacts.

Ferguson pointed to Texas, Oklahoma and California as examples of regions where changes in agriculture have increased reliance on groundwater, in turn depleting freshwater aquifers.

"If we have less water available from the rivers and falling out of the sky do we turn to the ground and ask for more from our wells?" he said.

"If you've already done some damage to those resources through energy production, have we created problems for ourselves for water resources over the next century?"

With files from CBC's Janani Whitfield