Since the end of the War of 1812, the U.S.-Canada border has been one of the more tranquil boundary areas in the world, populated by American and Canadian farmers mostly minding their own business.

So what could happen to disrupt this peaceful environment? Well, climate change might.

To be sure, the quirky way the rivers in the area intertwine with the boundary line has created difficulties, but they seemed solvable. By 1900, the border area in Alberta had been settled by Mormon farmers, who set up an expansive irrigation system relying on a steady water supply from the St. Mary River, a river that flows deep into Alberta but actually forms in Montana.

Then there is the Milk River, which flows north into Alberta but quickly curves back into Montana, where settlers were expanding their own irrigation works with the help of the Reclamation Act, passed by Congress in 1902, to provide funds for irrigation projects.

It wasn’t long before Montanans had built a diversion south of the border, pulling water from the St. Mary into the Milk River system before it could cross into Canada.

The Canadian response came quickly. In November 1903, engineers speedily dug out a 50-mile irrigation canal, which became known as “the Spite Ditch.” It had some major seepage problems, but for one day, it successfully filled with water, rediverting water from the Milk to the St. Mary that had originally been diverted from the St. Mary to the Milk in the United States.

This was the tit-for-tat that led to the Boundary Waters Treaty of 1909, which set the rules for how water from the two rivers would be apportioned between the two nations every year. It also helped establish the International Joint Commission to make sure the treaty terms were regularly followed.

But since then, the climate has changed and the treaty hasn’t, a situation that has grown to become a festering “borderland” problem.

While the border immediately west of the Great Lakes – home to the Red River and Souris River basins – is expected to get wetter as the climate changes, the plains that extend farther west, running up to the Rocky Mountains, are expected to dry out. If that was uniform on both sides of the border, solutions would be easier. But lately, Mother Nature hasn’t been a great respecter of traditions, treaties or boundary lines.

According to the National Drought Mitigation Center, the Western prairies are already experiencing moderate drought in some areas, particularly farther south. The region experiences very little rainfall and relies heavily on its river systems – replenished by spring snowmelt from the Rockies – to feed crops and livestock, according to David Sauchyn, a climate scientist at the University of Regina, Saskatchewan.

And this state of affairs won’t remain stable, either. As the climate changes, spring snowmelt is expected to decline and rainfall is expected to become less frequent. The snowmelt that does occur is expected to happen earlier in the spring, as well, leaving less water for later in the summer. Meanwhile, the lengthening growing season in the Western prairies, which are becoming warmer, probably means increased demand for water – even as water availability declines.

How a settled system becomes ‘precarious’

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.

“Very little of the water on the plains you get from the sky. Mostly, you get water from rivers,” Sauchyn said.

“If a river is confined to one state or one province of one country, it’s still challenging to adapt to a changing water supply,” Sauchyn explained. “But then, if that river system is crossing state boundaries, international boundaries, that makes it that much more complicated.”

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.

The mañana approach to maintenance

Tim Romanow, executive director of the Milk River Watershed Council in Canada, said that Montana has been working on a “fix on fail basis” with the canal system, meaning that instead of making infrastructure upgrades as soon as possible, it has only been making repairs when absolutely necessary.

“They basically haven’t invested a dollar in the infrastructure since it was built, to the point that it’s close to failure,” he added.

The diversion was scheduled to be receive maintenance in 2008, Romanow said, but when the Great Recession hit in 2008, the financing disappeared, and the project has remained a low priority for the U.S. Army Corps of Engineers.

If the canal system were to fail, the consequences – at least for Albertans along the Milk River – could be severe. “If that diversion infrastructure fails our river is dry in a day, and that water is critically important,” Romanow explained.

Past infrastructure failures have shut the system down for a week or two, he added, and they caused “significant challenges” on the Alberta side of the basin. Research on tree rings by Sauchyn, the climate scientist, shows that historically, droughts in the region have been severe. In the mid-1800s, they may have lasted for decades.

Although none of that magnitude have hit the watershed since the treaty was written and the cross-border irrigation system was installed, the research does raise a question. “What if that happened in the future? What the heck would we do?” Sauchyn asked.

“Our situation is precarious at best to begin with in terms of water availability and water scarcity issues,” he added.

Montana braces for a challenge

Besides thinking about the need for repairs, officials in the watershed have also started to ponder building storage basins throughout the watershed to try and hang onto as much spring runoff as possible.

Kelsey Jencso, Montana’s state climatologist, said in an interview with a local magazine earlier this year that groundwater banking, increased irrigation efficiency and a better accounting of water use could all be part of an effort to help increase water conservation in the state.

“The management and conservation of Montana’s water supplies is going to be one of the toughest environmental challenges during the next century,” he told the magazine.

For many on the ground in Montana, investment in new and resilient watershed infrastructure today could help the region endure the climate change stresses of tomorrow. But whether that infrastructure will materialize is another question.

Under the terms of the 1909 treaty, infrastructure projects that would affect the natural level or flow of boundary waters need to either be approved by both governments through an independent bilateral treaty, like the Columbia River Treaty, or applied for through the International Joint Commission (IJC) – a binational body tasked with managing boundary waters.

But the unpredictability of water levels, especially as the climate continues to change this century, is complicating plans for adaptation and mitigation in the Milk River watershed.

With the looming possibilities of both both extreme flooding and extreme drought, it’s difficult to build facilities that can handle both extremes, according to Frank Bevacqua, a public affairs officer at the IJC.

Dueling emergency plans?

Flood management plans call on water managers to draw down reservoirs so there’s enough storage available to reduce the impact of a spring flood, but drought management plans call on water managers to draw up enough water to ensure that there are sufficient supplies for irrigation season.

“You can see how these two objectives are at cross-purposes – one says store more water, the other says store less water,” Bevacqua added. “If the frequency and severity of both floods and droughts increases, it becomes more difficult to manage effectively for both.”

A March 2012 report from the U.S. Bureau of Reclamation found that existing irrigation water shortages in the basin average around 71,000 acre-feet per year – about 36 percent of the amount of water needed for optimal crop growth.

This unmet crop demand affects farmers’ willingness to invest in the necessary equipment and infrastructure to diversify to more drought-resistant crops, which in turn contribute to further water shortages.

Montana officials have been leading discussions with Alberta to see if changes would be possible to, in Montana’s view, “more equally share those waters,” according to Brent Esplin, area manager for the U.S. Bureau of Reclamation’s Montana Area Office.

“They haven’t really come up with any changes that both sides would support,” Esplin added.