Alberta's Milk River water level to drop due to pipeline break

Officials say a "catastrophic failure" on a pipeline in Montana, near the Carway, Alta., border crossing, is expected to impact Alberta's Milk River over the next several days.

According to the Milk River Project, an agency that delivers irrigation water to more than 120,000 acres of land in Canada the U.S., the St. Mary siphon on the St. Mary Canal outside Babb, Mont., burst at 9 a.m. on June 17.

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Officials say personnel were monitoring a crack at the time.

"Thankfully, no one was hurt, but the damage is extensive," the Milk River Project said on Facebook.

"The canal was shut down prior to the failure, but the hillside, Hook's Hide-Away bar, hotel, and roping arena have all been significantly impacted with the water."

The Milk River Watershed Council Canada (MRWCC) said debris and water is flowing down the St. Mary River along the Canadian Reach through to the St. Mary's Reservoir.

"Please be careful in low-lying areas and along unstable banks," the MRWCC said in a statement. "The canal diversion gates were closed at the time of the failure for the inspection."

“As a default of them not being able to receive the water through that diversion, because they're obviously going to have it shut off at this stage until they can repair the siphon, more water will flow up the St. Mary River and that means more water should be received at the St. Mary Reservoir,” said David Westwood, the general manager of the St. Mary Irrigation District.

The MRWCC estimates flows will drop on the North Fork Milk River within 24 to 48 hours.

"Natural flows on Milk River in combination with the current rain should maintain approximately five or six cubic metres per second for water users. This will likely drop with depletion of the bank aquifers."

The water quality will also decline as the river’s level drops.

“When we get down to natural flow, only which we're going to see by next week the salt content increase. There's more phosphorus and nitrogen in the water which makes it more of a challenge to for the treatment systems to process the water to have good domestic water, treated water,” Tim Romanow, the executive director of the Milk River Watershed Council, said.

Recreational activity on Milk River is not recommended at this time as "flows will drop very suddenly," the MRWCC said.

The Montana office of the U.S. Bureau of Reclamation said Monday the breach caused local flooding and erosion, with washout areas estimated to be between nine to 15 metres (30 to 50 feet) deep.

"This breach has affected residents and surrounding communities directly or indirectly. Emergency response teams, and local law enforcement are involved in the response efforts," officials said.

"The Bureau of Reclamation is coordinating with the Gallatin County Sheriff’s Department, Blackfeet Tribe, National Park Service, Glacier County Sheriff’s Department, and Glacier Electric to limit the impacts of the breach and ensure people remain safe."

It said the flooding also caused property damage, impacted local infrastructure and created a risk to public safety.

"Roads are closed, and utilities may potentially be disrupted in the affected areas. Traffic cones and caution tape have been placed to limit access to potentially dangerous areas," the bureau said.

"Reclamation and local authorities responded quickly to the breach and will be conducting damage assessments to the St. Mary system, local property and surrounding areas. Residents are advised to avoid the area and follow evacuation or safety orders from local authorities."

The MRWCC expects to share more information on the situation as it becomes available.