Did you know… Although Prior Lake is naturally landlocked, the Prior Lake Outlet Structure allows water to discharge from the lake! In fact, whenever the lake level is 902.5 feet or higher, the lake is continuously discharging!
Click this link to watch a video of the outlet structure in action.
(You will be directed to our YouTube Channel.)
The PLSLWD first constructed the Prior Lake Outlet Structure in 1983, to address flooding issues on Prior Lake. The outlet structure receives water from the lake and discharges it into the Prior Lake Outlet Channel. Visit the Prior lake Outlet Channel tab to learn more about the history of the outlet system.
The original outlet structure had a manually-operated front slide gate and 156 side gates. It was designed to drain 50 cubic feet per second. A 7-mile channel was constructed from Prior Lake through Shakopee to the Minnesota River. The cost of the entire project was $1,025,000, and 74% of this cost was paid for by 898 lakefront property owners.
Normal wear and tear on the outlet structure eventually resulted in cracking to the structure and diminishing efficiency. In 2007, partners and advisers developed a strategy and plan for updating the outlet system called the Multi-year Outlet and Channel Improvement Project. At that time, a Memorandum of Agreement was signed between Prior Lake, Shakopee, Shakopee Mdewakanton Sioux Community and PLSLWD. These “cooperators” manage the structure and channel. Jointly, they support maintenance of the structure and the channel.
In 2010, the structure was replaced with an accordion-shaped fixed crest weir that allows for constant water discharge as soon as the lake level reaches the weir height of 902.50 feet. The updated structure was constructed with a low-flow gate to allow manual discharge of water between 902.0 and 902.5 feet. To open the low-flow gate, the District must follow the 2004 Outlet Structure Management Policy and Operating Procedures and request permission from the Department of Natural Resources.
Water discharges through the outlet structure quickly flows into the outlet channel. It travels underground for nearly one-half mile through a 36 inch pipe and is released to an open portion of the channel near highway 21. The current structure allows a maximum of 65 cubic feet per second to drain out of the pipe.
During the 2014 flood, the outlet structure operated continually and discharged into the outlet channel at full capacity.
Fact Sheet: Prior Lake Outlet Structure