Leak hits St. Mary Diversion

A small leak that was discovered Thursday on part of the St. Mary Diversion is being monitored by the Bureau of Reclamation and Milk River Irrigation Project Joint Board of Control.

Jennifer Patrick, project manager of the Board of Control, said the leak was discovered by BOR crews Thursday on the bottom of a buried siphon along the St. Mary Diversion in the Babb area.

“It’s small right now; it’s a very small leak,” Patrick said this morning.

She said water delivery is continuing as normal through the St. Mary Diversion and if the condition changes water users will be notified.

The St. Mary Diversion is a 29-mile system of dams, dikes and siphons that transfers water from the St. Mary River into the Milk River, providing water for irrigators and communities including Havre, Chinook and Harlem.

Water is stored in Lake Sherburne near the edge of Glacier National Park and transferred from St. Mary River to the north fork of the Milk River where it flows into Canada and back down into Montana.

Patrick said the BOR is usually good at finding and fixing leaks, but the latest  leak is more difficult to fix the crack is on the bottom of an underground siphon making it harder for crews to get to and repair.

She said if the leak was on the top of the siphon it could be fixed by shutting down some flows, but a leak at the bottom is harder for crews to get to and would require the whole system be shut down.

If the siphon develops a larger crack, Patrick said the Fresno Reservoir “would be in a tough situation.”

She said the reservoir has 58,000 water acre feet and 2,000 is coming out in a 24-hour period. Because of dry weather conditions and a lack of rainfall, the reservoir would empty out at a faster rate than water would come in if a significant leak occurred in the diversion, she said.

The St. Mary Rehabilitation Working Group was created in 2003 to find ways to rehabilitate the project, one of the first projects the Bureau of Reclamation was authorized to build after it was created 1902. Historically, the maintenance and repair of the diversion has been funded by its users, primarily irrigators.