St. Mary Canal Siphon Failure outside Babb, Montana

On June 17, 2024, at approximately 8:45 a.m., the St. Mary Canal Siphon breached just outside Babb, Montana, causing significant local flooding and erosion. The breach led to washout areas estimated to be 30 to 50 feet deep. At the time of the failure, diversions to the canal were at 600 cubic feet per second (cfs). Although diversions have been stopped, flows are expected to continue for 24 to 36 hours while the canal drains.

This breach has affected residents and surrounding communities either indirectly or directly. Emergency response teams and local law enforcement are actively involved in the response efforts. 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 public safety.

“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, helping mitigate the potential for additional flooding in the surrounding area.”

The flooding has caused localized property damage near the breach, impacted local infrastructure, and posed risks to public safety. Roads are closed, and utilities may be disrupted in the affected areas. Traffic cones and caution tape have been placed to limit access to potentially dangerous areas.

Reclamation and local authorities responded quickly to the breach and are 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 Bureau of Reclamation is coordinating assets and experts to assess the damage and determine the potential cause of the failure. Both short-term solutions and long-term rebuild options are being evaluated. Detailed inspections will commence as soon as the water empties from the line and the surrounding ground is determined to be stable.

Completed in 1915, the St. Mary Canal diverts water from the St. Mary River to the North Fork of the Milk River in Montana. It is a critical infrastructure component for water management in the region, serving 120,000 acres of irrigated land and approximately 18,000 municipal users.