Residents of Montana opposed to plans for a coal mine in B.C. have asked the state to fund a study of the current water quality in the Flathead River, which flows from Canada into the U.S.

That way, they say, if the mine were built in the now-pristine valley just across the border in southeastern B.C., they would be able to measure any subsequent pollution on their side of the border.

State Senator Greg Barkus, who supports spending the $300,000 requested by a state agency for the study, said Montana needs a thorough analysis now, so they could prove the mine was polluting the river later.

"So that we do know if something is happening north of the border, that we have got at least a baseline data collection where we can then establish, yes, that mine is doing something to the quality of the water."

Canadian-based Cline Mining wants to build the mine, which would  produce two million tonnes of coal a year, near the ski-resort community of Fernie.

While it does not yet have permission from the B.C. government to build the mine, it is hoping to start work on it in the next few years.

Barkus said if the mine goes ahead, his constituents want to know exactly what's leaching out of the mine into the river, and then downstream into the U.S.

"You know, there's just a deep sense of concern by a large number of people," he told CBC News.

Barkus thinks the request for the $300,000 needed to conduct the study will be approved in the next few weeks.

Eventually, he hopes, a treaty can be developed for the region that would impose strict pollution limits on both sides of the border.