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Siphon at St. Mary Canal suffers 'catastrophic failure'

'Catastrophic failure' of siphon at St. Mary Canal
'Catastrophic failure' of siphon at St. Mary Canal
Posted at 2:17 PM, Jun 17, 2024

The Milk River Project said on Monday that the St. Mary siphon on the St. Mary Canal north of the community of Babb suffered a "catastrophic failure."

It reportedly happened while U.S. Bureau of Reclamation personnel were monitoring a crack.

The agency said no one was hurt but the damage is extensive.

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

The Blackfeet Tribal Business Council posted on Facebook: "The St.Mary Canal/Milk River in Babb is closed to all river activities. No floating, boating/rafting, swimming, etc. for the week of Monday June 17, 2024 to Monday June 24, 2024. Road closure to Camp 9 Road (Hook’s Hideaway) - all roads are closed in these areas."

'Catastrophic failure' of siphon at St. Mary Canal

People are asked to stay out of the area as they are still evaluating the extent of the damage.

The Bureau of Reclamation said in a news release that the breach caused local flooding and erosion, with some areas resulting in washout areas estimated to be 30 to 50 feet deep.

Diversions to the canal were 600 cubic feet per second at the time of failure. Diversions have been stopped, but flows are expected to continue for as long as 24 to 36 hours while the canal drains.

“Emergency response teams have been deployed to contain and evaluate the damage,” said Ryan Newman, Reclamation’s Montana Area Office Manager. “Water flows were naturally diverted back to the St. Mary River and helped mitigate the potential for additional flooding in the surrounding area.”

'Catastrophic failure' of siphon at St. Mary Canal
'Catastrophic failure' of siphon at St. Mary Canal

The agency says the flooding has caused property damage in direct proximity to the breach, impacted infrastructure, and may pose risks 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.

From the Bureau of Reclamation website:

The St. Mary Diversion Dam and Canal were completed in 1915 as part of the Milk River Project (Project) in north-central Montana. The dam is located near Babb, MT and approximately 0.75 miles downstream from Lower St. Mary Lake. The existing dam consists of a 198-foot long and 6-foot-high concrete weir and sluiceway. It diverts water from the St. Mary River into the St. Mary Canal through the gated headworks structure for use by the Milk River Project.

(UPDATE, 3 pm) Officials with the Milk River Project provided this update: "We were hopeful the structures would hold, but at around 1:51 PM on June 17th, the St. Mary Siphon suffered a catastrophic failure at the inlet of both siphon tubes. The powerful water flow caused the 100+ year-old siphons to break apart, washing away the concrete structures holding the pipes underneath."

U.S. Senator Jon Tester of Montana said on X: "I’m monitoring the failure of the St. Mary Siphon and have pressed federal officials for immediate attention to the situation. As the full extent of the damage is evaluated, I'll continue to be in touch with local leaders and encourage folks to remain away from the affected area."

U.S. Representative Ryan Zinke of Montana on X: "I’m monitoring the St Mary’s siphon failure in Babb closely. Thankfully no injuries reported but please heed the advice of public safety officials and avoid the area. The St Mary’s is critical infrastructure delivering water down nearly the entire hi-line. My office is working closely with the state and feds and ready to provide any assistance in my power."

U.S. Representative Matt Rosendale on X: "I am monitoring the situation and have been in contact with the Milk River Irrigation Project Joint Board of Control, please reach out if you need assistance."

U.S. Senator Steve Daines on X: "I'm monitoring the concerning siphon breach on the St. Mary Canal and have been in contact with local irrigators as well as the Bureau of Reclamation. The damage is serious, and I'm standing by to help local authorities in any way necessary."

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