At the posted coordinates, there is a white gauge. Depending on the water level, you probably will not be able to read it from shore. This cache is rated as it is because it will require you to either use waders, or a boat to get to the sign. Also, due to the nature of the information on it, it is probably only accessible when the water is thawed. This will likely not work in the winter, as part of the necessary information will be encased in ice.
On the sign, there are numbers. For the purpose of this multi, you must disregard decimal places. E.g. 102.00 would be 10200, and treated as ten thousand, two hundred. Leading zeroes should NOT be stripped!
A = the very top, small font number, on the gauge.
B = the very bottom, large font number, on the gauge (below the water level).
Final coordinates are:
N45 14.(B+016) W093 21.(A-076)
05/31/2018 - as of this spring, it seems the lower number on the gauge (B) changed. Please use the new math. However, it's possible that I just saw a reflection, so if this math doesn't work, use B+006 (old math) instead.
Please note - this cache is in a potentially dangerous location and seeking it is done at your own risk! There is no such thing as safe ice in the winter. Legal entry points (PWAs) are provided, other entry points may be considered trespassing on private property. The terrain rating reflects the need to travel on water.
Since checkers are a good thing:
You can validate your puzzle solution with certitude.