International Rainy-Lake of the Woods Watershed Board

Monitor water levels and flows

International Rainy Lake of the Woods Watershed Board monitors water levels and flows on the Rainy River, Rainy Lake and Namakan chain of lakes.

As did the International Rainy Lake Board of Control before the 2013 creation of the Watershed Board, a Water Levels Committee ensures that the operation of the dams follow the Orders of the International Joint Commission.  The latest Orders are the 2000 Consolidated Orders and consist of a rule curve band for Rainy Lake and one for the Namakan chain of lakes, with minimum releases in times of low inflows and all gates open levels in times of high inflows.

The rule curves provide an upper and lower limit for the water elevation in the reservoir at any day of the year, lower in the winter and higher in the summer.  The companies which operate the dams target the middle portion of the rule curves, except when directed otherwise by the Water Level Committee. 

In times of extremely low inflow for that time of year, the water level may go below the rule curve; however a minimum release comes into effect to ensure there’s sufficient water downstream.  In times of extremely high inflows for that time of year, water levels may go above the rule curve because the outlet capacity is unable to release as much water as is coming into the reservoir, even with all gates fully open.

The Water Levels Committee maintains a list of people whom it notifies in cases of drastic outflow changes and has a fish spawning protocol to protect the desiccation of eggs from lowering outflows.

A provision of the 2000 Consolidated Orders calls for the evaluation of the rule curves after 15 years which means that the Watershed Board and the International Joint Commission have sponsored some two dozen studies to evaluate the performance of various economic and ecological indicators under the latest two sets of rule curves.  The earlier set dates from 1970.  The Rainy and Namakan Lakes Rule Curve Review Study Board will report on their evaluation in May 2017.