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WATCH: Drone video captures failure of St. Mary Canal siphon

Glacier County Office of Emergency Management
Posted at 11:40 AM, Jun 18, 2024

GREAT FALLS — The Glacier County Office of Emergency Management flew a drone over the area affected by the "catastrophic failure" of the St. Mary Canal siphon northeast of Babb on Monday, June 17, 2024.

The agency said in a news release that the overflight was conducted to assess the damage. The main focus was life safety and making sure there were no people in distress.

Once the scene was secured, GCOEM, with the assistance of Blackfeet Homeland Security/DES conducted flights surveying the area for individuals in distress; finding none, this overflight of the siphon was made.

WATCH:

Drone video: failure of St. Mary Canal siphon

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 (cfs) 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.”

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.

'Catastrophic failure' of siphon at St. Mary Canal

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.

We will update you when we get more information.