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Droughts Hit Central Basins, Testing Water Managers
IJC admin | 2018/02/16
By Kevin Bunch, IJC
A “flash drought” in the summer of 2017 squeezed water supplies in transboundary watersheds in Alberta, Saskatchewan, Manitoba, North Dakota and Montana, complicating the task of water managers to make sure everyone gets their share.
Dr. Adnan Akyuz, climatologist at the North Dakota State Climate Office, said the fall and winter of 2016 were unusually wet – the ninth wettest on records going back to 1890 in the state. But the opposite trend hit from March through July of 2017, when the state – as well as Montana, Alberta, Saskatchewan, and Manitoba – started getting drier. Areas to the west were taking the brunt of the drought.
The Milk River saw one of its driest periods on record during the summer and fall of 2017. Water users in Canada and the United States ceased irrigation practices in August. Credit: Milk River Watershed Alliance
St. Mary and Milk rivers faced ‘flash drought’
“From June to September, we had maybe 25 percent of the average annual rainfall,” said Jeff Woodward, Canadian field representative with the IJC’s Accredited Officers of the St. Mary-Milk Rivers and water resources engineer with Environment and Climate Change Canada. “In southern Saskatchewan … there was no appreciable rainfall between June and September, and that’s really an anomaly.”
2017 started off with nearly full reservoirs in the Alberta-Montana-Saskatchewan St. Mary-Milk basin, Woodward said, following a wet period that left water supplies either near or above average. But as the abnormally dry summer months went on, the accredited officers started facing problems with the apportionment of water.
The Accredited Officers was established by the Boundary Waters Treaty between the Canadian and US governments in 1909 to measure water flows in the boundary-crossing St. Mary and Milk rivers, which were connected by a manmade canal in 1917 to bring water from the St. Mary River into the Milk and divide it up between the two countries (a 1921 IJC order provides guidance on how that’s done). The apportionment of water each country gets also is based on water supplies, and water users are forced to make due with less in a drought situation. Upstream reservoirs can provide some relief by holding water back for later in the season.
Under the Accredited Officers’ Letter of Intent, the Canadians can only use more of their share from the Milk River later in the season – around June through September – if the United States uses more than its share of water from the St. Mary River earlier in the season, typically the March-May period. These deficits are designed to balance out at the end of the irrigation period. Woodward said the wet spring meant reservoirs on the St. Mary River were full, so there was no opportunity or need for US water managers to use more than their share of water during the spring freshet, leaving no “extra” water for Canada in the drought months.
“It got to the point where there was water flowing in the Milk River system diverted from the St. Mary, but there was no natural flow on the Milk River system itself,” Woodward said. All the water flowing on the Milk at that point was US water stored by dams the St. Mary River diverted across the canal. “So all the flow we saw (on the Milk River) in Canada was American water.”
As a result, on Aug. 3, 2017, the officers put a stop to consumptive uses of that river water in Canada as it was water the country wasn’t entitled to under the agreement, Woodward said. The United States did the same thing to halt usage of water in the system, he added. By the end of the season, he said the Accredited Officers and water users were able to offset the imbalance, thanks in part to the flexibility in the agreement between the two countries.
Nevertheless, Woodward said the impacts of climate change seem to be playing out with more extreme weather in the basin, and there’s little more the officers can do to manage water. He said he believes there should be more discussions and planning on structural investments such as new reservoirs and improvements to the water diversions, or possibly adjusting how the allocations are managed.
“It highlights the need to have those Letter of Intent discussions every year,” Woodward said. “The things we anticipate in the past aren’t the scenarios we are dealing with now.”
This isn’t to say nothing is happening, however. There have been discussions ongoing through the Montana-Alberta St. Mary and Milk Rivers Water Management Initiative. The initiative is reviewing how improve access to the shared water of the St. Mary and Milk Rivers, including through water storage and improvements to the St. Mary-Milk canal.
The IJC supports having the field representatives and the accredited officers review the Administrative Procedures (which document how the natural flows are to be calculated) and the Letters of Intent that they use to guide apportionment, and then provide the IJC with a report on next steps.
As of January 2018, the current snowpack and predicted spring streamflows are normal or near normal, according to US Field Representative John Kilpatrick.
Souris River saw water restrictions in southern portion
The Souris River starts in Saskatchewan before flowing into North Dakota and Manitoba. Credit: Karl Musser
To the east, drought conditions have been hitting the Souris River and Red River basins. The Souris, which crosses from Saskatchewan into North Dakota before turning back north into Manitoba, sits on the west end of the state, while the Red River divides North Dakota and Minnesota on its way into Manitoba.
A drought map of Canadian provinces from the end of summer 2017 shows dry conditions and droughts still being an issue in Saskatchewan and Manitoba. Credit: Agriculture and Agri-Food Canada
A summer 2017 drought map of the continental United States shows drought conditions centered on Montana, with overlap in surrounding states. Credit: National Drought Mitigation Center
On the International Souris River Board, US Co-Chair Garland Erbele – who also serves as North Dakota’s state engineer – said a heavy snowpack developed in southern Saskatchewan and Manitoba and northern North Dakota over the winter in 2017. After the US National Weather Service (NWS) signaled a significant flooding possibility, the board drew down its reservoirs more than normal to provide enough flood storage space for a major runoff event. By March and April of 2017, it was apparent that the area wasn’t getting the usual amount of precipitation anticipated. The snow also melted in an “ideal thaw,” Erbele said, with weather above freezing during the day and below freezing at night, which limited flooding to the low end of the Souris River. The cumulative effect of these conditions saw water flows in the river getting low.
“There was a lot of demand for water, as happens in a drought,” Erbele said. “We are required to pass 20 (cubic feet a second) of water into Canada on the bottom end of the river (in North Dakota) into Manitoba, and while we were able to do that most of the year, there was short period of time where flows dropped below the level required to pass.” Other than that period, Erbele said there weren’t other flow issues on the Souris during the drought, though Minot put water restrictions in place on the southern end of the river.
Akyuz said it was the first time since 2006 that the state had experienced an “exceptional drought” as designated by the NWS, and the region at large saw an active fire year. The water that did exist in pools had quality issues and would become inundated with algae, he added. Steady precipitation helped end the drought in the eastern half of North Dakota, but the western half is still dealing with it to some degree as of Jan. 16, according to the US Drought Monitor.
Most of Manitoba escaped drought conditions in 2017 thanks to the snowpack and moisture in the soil, though central Saskatchewan suffered from severe drought conditions too, according to Agriculture and Agri-Food Canada. Eastern Saskatchewan and much of southern Manitoba are seeing abnormally dry conditions this winter, however.
Kevin Bunch is a writer-communications specialist at the IJC’s US Section office in Washington, D.C.