Saturday, September 13, 2014

How Climate Change May Disrupt the Tranquility Along the U.S.-Canada Border

A siphon for the St. Mary Diversion.  (Credit: Ed Sloboda / MRWCC) Click to enlarge.
Spring snow and ice melt from glaciers in northern Montana's Glacier National Park has historically been a primary source of water that recharges the prairie cropland each year.  But the park, which used to have as many as 185 glaciers, is now down to 25.  All the glaciers could be gone in a matter of years.
The Milk and St. Mary rivers form near the border in Montana and wind up through Alberta. The Milk then wheels southeast and flows back into Montana, while the St. Mary continues north, eventually flowing into the Saskatchewan River and draining into the Hudson Bay.

The Boundary Waters Treaty of 1909 stipulates that Montana gets 60 percent of the Milk River flow each year, while Alberta gets 60 percent of the St. Mary flow.  But with both countries controlling each other's access to water, the disruption of climate change is making a mess out of what was a delicate environmental and political balance.

A sophisticated and expensive system of dams and irrigation channels has maximized the amount of water that the region can pull from both systems over the last 100 years.  The plumbing includes a diversion point in the St. Mary River that takes water from the St. Mary to the Milk before both cross into Alberta.  The result provides up to 80 percent of the Milk River's streamflow in that area during the summer.

But much of this plumbing hasn't been replaced or sufficiently repaired since it was installed. Officials and farmers in the watershed now worry that the decaying state of the irrigation system between the two rivers is wasting water on land that already has some.  Meanwhile, the farmland that hosts 135,000 acres of crops is drying out.

How Climate Change May Disrupt the Tranquility Along the U.S.-Canada Border

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