Milk River irrigators ordered to cease withdrawals for 2026

Posted on May 21, 2026 by admin

Dr. Wayne Jenkinson and
John Kilpatrick
Canada/U.S. Accredited Officers
for the St. Mary and Milk Rivers

Hydrological conditions in the St. Mary and Milk River basin are exceptionally dry this year due to the combined effects of below-normal snowpack, persistent warm temperatures, and limited effective precipitation, all of which have constrained runoff and reduced river flows. 

Provisional data indicate that the natural flow of the Milk River has been zero or near-zero since April 15. According to the Accredited Officers’ Procedures for the Division of the Waters of the St. Mary and Milk Rivers, which are consistent with the 1921 Order and the Boundary Waters Treaty (BWT), Canada will have underdelivered approximately 107 acre-feet of water to the United States as of May 15. All water reaching the Milk River in Canada is United States St. Mary River water diverted through the St. Mary Canal. With no foreseeable possibility of repayment of this deficit, the Accredited Officers regret to inform irrigators within the Milk River basin in Canada that in order to comply with the Treaty they must cease withdrawals from the Milk River. The Accredited Officers recognize that this decision will significantly impact water users in the Milk River in Canada.

In addition, the basin continues to feel the impacts of ongoing multi-year moisture deficits and recent drought conditions, along with periods of below-average precipitation during critical spring and early summer months. Irrigators across the basin in both countries are likely to be impacted by these conditions.

The hydrometric data for the St. Mary and Milk River basins, jointly generated and maintained by the US Geological Survey and Environment and Climate Change Canada, is founded on internationally recognized standards of measurement, rigorous quality assurance protocols, and decades of operational expertise. Both agencies employ calibrated instrumentation, standardized field procedures, and continuous verification processes to ensure accuracy and traceability. Moreover, the long-standing transboundary collaboration between Canada and the United States reinforces data consistency through harmonized methodologies, and mutual auditing practices. As a result, this dataset is widely regarded as highly dependable, reproducible, and fit for critical applications including water allocation, and binational treaty compliance.

The International Joint Commission’s (IJC) International St. Mary and Milk River Study will play a critical role in strengthening and modernizing the administrative procedures of the Accredited Officers. At its conclusion, it will make recommendations to the International Joint Commission that should provide a comprehensive, science-based assessment of how each country’s receipt of its entitlements can be achieved through new and existing infrastructure and modifications to the Accredited Officers’ administrative procedures. The study will equip the Accredited Officers with greater information, and improved models and decision-support tools. Ultimately, this work will enable Accredited Officers to administer the provisions of the BWT with greater efficiency, clarity, and resilience, ensuring continued equitable and sustainable water management for both countries. 

The Study Board will submit its final report and recommendations to the IJC this fall. The IJC will seek input from the Accredited Officers prior to providing its own recommendations to the governments of Canada and the United States.