The cache is NOT at the posted coordinates.
This is a bonus cache. You must first complete the Adventure Lab cache called "Decorah: A Driftless Adventure". When you have completed the lab cache, Journal Entry 5 will give you a word to enter in the checker. The correct word will give you the coordinates for the final.
The actual terrain for this cache is a 1/1.5. The posted DT is for the adventure.
You can validate your puzzle solution with certitude.