International Study Proposed Inflatable St. Mary Dams
The International Joint Commission study suggests new infrastructure to secure water entitlements for the U.S. and Canada.
Updated on Sept. 20, 2026 in Utilities
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Published in July 2026, the International St. Mary and Milk Rivers Study proposed installing inflatable dams on St. Mary and Lower St. Mary lakes. The initiative aims to address long-term water entitlement stability for both nations amid changing climate conditions.
Why it matters
Infrastructure limitations and climate-driven hydrological shifts threaten the reliability of water delivery for irrigation and other uses. The proposed dams seek to preserve spring freshet water for later use, potentially balancing needs across the border.
The proposed dams would hold approximately 5.4 billion gallons of water, representing 16,800 acre-feet of seasonal storage. These improvements aim to support an increased canal flow of 850 cubic feet per second.
The players
International Joint Commission
This binational organization manages water use and quality across the border between the United States and Canada.
The details
The project would install inflatable structures to retain water, complementing an upgrade to the St. Mary Canal which originally dates back to 1915. This infrastructure plan follows a major canal failure in June 2024 that highlighted the fragility of the existing siphons and control systems.
Timeline
The St. Mary Canal was originally constructed in 1915.
A major failure impacted the St. Mary Canal in June 2024.
The International St. Mary and Milk Rivers Study was published in July 2026.
The public comment period for the study concluded on August 31, 2026.
Market Landscape
This proposal reflects a shift toward adapting cross-border infrastructure to meet long-term hydrological stability targets. It aligns with the International Joint Commission's transboundary water management protocols, updating water distribution strategies for the next 100 years.
While the project aims to stabilize water entitlements, it includes projected economic trade-offs, with Canada potentially gaining $19 million to $33 million annually and the U.S. facing $4 million to $8 million in annual losses. Implementation will depend on future budgetary decisions regarding this infrastructure investment.
The takeaway
The study suggests that proactive infrastructure management can maintain water entitlements for the next century despite shifting climate patterns. Successful implementation of these dams would rely on resolving the differing economic impacts projected for the U.S. and Canadian regions.
Further reading
Learn more about the evolving management of Utilities and infrastructure planning.
Source note: This article includes information reported by The Daily Inter Lake.
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