The Prior Lake Outlet Structure’s low-flow gate is scheduled to be opened next Tuesday, March 5. The low-flow gate’s primary purpose is to lower lake levels and create more storage on the lake for snow-melt and spring rains when risk of flooding is anticipated. The DNR has pre-approved the District to open the low-flow gate in March and April if necessary.
The Prior Lake Outlet Structure automatically stops discharging when the lake level drops below 902.5 feet. When the low-flow gate is open, lake levels can drop slightly faster and to (no lower than) 902.0 feet. Rain, snowmelt, and flow from upstream lakes may prevent the lake from dropping or getting this low before the end of April. When the lake is above 903’, the low-flow gate is ineffective as the outlet pipe is limiting the amount of flow leaving the lake. Current lake levels can be found here.
The Outlet Structure has been discharging water continuously since September 2018. Even though the lake is frozen, the water at the Outlet does not freeze when levels are above 902.5’ because the water is moving quickly. Lake levels have been relatively steady because the amount of water flowing in from Spring Lake and other tributaries has been relatively equal to the amount leaving Prior Lake. By opening the low-flow gate now, the amount of water leaving the lake should be more than coming in so the lake should slowly drop. Please note, the low-flow gate does NOT prevent flooding, but may reduce the severity of flooding. For more interesting information, pictures, and videos about the Outlet Structure and low-flow gate, please view this StoryMap here.