The Minnesota’s Department of Natural Resources has authority over many aspects of lake management and usage,  including  “weed” removal, water treatments, rip-rap, docks,  boat ramps, sand blankets. The DNR’s jurisdiction includes waters that lie below the Ordinary High Water Level (OHWL). 

*Source MNDNR

For lakes and wetlands, the OHWL is the highest elevation that has been maintained so as to leave evidence on the landscape. It is commonly that point where the natural vegetation changes from predominantly aquatic to predominantly terrestrial.

The DNR has established the Ordinary High Water Level for Detroit and Curfman Lakes at 1334.3 feet above sea level based upon the NGVD 29 (ft) datum.   PRWD maintains and publishes current lake level information.   

In many instances work below the OHWL requires a specific permit.   In other cases, including docks,  ice-ridge repair, a general statewide permit is issued, and as long as work complies,  no additional permit is required.