Metallic UFO over Nimrod, Minnesota, on July 2011

On July 4, 2011, a strange metallic UFO was taken on picture over Nimrod, Minnesota, USA. What is it?

Witness report:

This picture was taken on a 4th of July camping trip in 2011 on the Crow Wing River in Nimrod, Minnesota. I was looking South down the river. I did not notice the object when I took the picture and only discovered it when I was going through old photos this week.

Source, 29th March 2018