Manitoba Transportation and Infrastructure has increased the outflow from the Shellmouth Reservoir (Lake of the Prairies) as part of a standard winter drawdown to prepare for the spring 2026 melt. In a Jan. 16, 2026 media bulletin the province’s Hydrologic Forecast Centre said outflow was raised from 300 cubic feet per second (cfs) to 400 cfs to create storage for anticipated spring runoff.
The drawdown is a routine measure to lower reservoir levels and reduce flood risk. Officials note that the increased release will raise water levels on the Assiniboine River — by roughly a half-foot between Shellmouth and Brandon, according to the province — even as it lowers the reservoir itself. While the Shellmouth Dam is located in western Manitoba on the Assiniboine, provincial hydrologists say the operation is a prompt for residents across the province to monitor local drains and creek ice, including Stonewall’s Grassmere Drain, because changing operations and moving water can make ice unsafe and can cause rapid level fluctuations in small channels.
Local emergency officials are advising residents to sign up for the CodeRED notification system via the Town of Stonewall website to receive any urgent notices. The Town of Stonewall lists Dennis Peterson as its Municipal Emergency Coordinator and as a contact for emergency management information.
The Manitoba 2025 Fall Conditions Report indicated soil moisture in parts of the Interlake was near‑normal to below‑normal heading into winter; the drawdown is being used as a precautionary step to reduce the risk of uncontrolled flooding during spring runoff. The province’s Hydrologic Forecast Centre also warns that ice which appears normal may be very thin after flow changes and should not be trusted to support people or vehicles.
Residents living near waterways can check the Manitoba River Conditions Map for real‑time sensor data and are encouraged to stay well back from creek and drain banks and the edges of ice until the spring runoff period has passed.
