Saskatchewan's north is dotted with many lakes. (CBC file)

Environmentalists in Saskatchewan are calling for federal intervention to halt what they say is an increasing threat to northern lakes and forests from acid rain linked to oilsands development in Alberta.

The Saskatchewan Environmental Society issued a news release Monday to say that data, obtained by the society from the Saskatchewan environment ministry, reveals that rain falling in the La Loche area of the province's far north has a pH level that falls under the definition for acid rain.

The generally accepted threshold for normal rain is a pH of 5.6. Environment Canada has determined any value less than five may be termed acid rain.

Ann Coxworth, a spokeswoman for the environmental society, said data from the Saskatchewan government shows the average pH level for rain and snow in the La Loche area is 4.96.

"We have now a combination of that region being the most sensitive forest soil in Canada, most sensitive to damage by acid precipitation and an increase in the acidity of the precipitation," Coxworth told CBC News on Monday. "So it seems to us that is a situation that really needs to be attended to."

The society wants the federal government to regulate emissions from Alberta's oilsands. It says pollution crossing provincial boundaries puts the issue under national jurisdiction.

Coxworth said if acid rain continues to fall unabated, it will destroy forests and lakes in Saskatchewan's northern region.

Coxworth said the federal government should impose regional caps on the amount of sulfur dioxide and nitrous oxide that activity associated with oilsands development can release into the atmosphere.