Boaters have told stories of being attacked while on the water, first hearing several loud knocks on the hull, followed by several violent back and forth swings of the boat.
Nielson wants people to try and see for themselves because this mysterious monster that's eluded most cameras for more than a century. He's offering $50,000 for undisputable photographic and scientific evidence.
Steven Raymond, lives in Lake City says, "I said slow down, and when I turned around and looked again, the log went under water."
Steven Raymond knows the people of Lake City, but he has no idea what he saw when fishing on Lake Pepin.
Steven says, "What we had seen was three distinct humps and one of the humps looked like a face sticking out of the water; just before he slowed the boat down, I took a picture."
That was three years ago and Steven says he can't find the picture.
For decades folks around Lake Pepin have told tales of a "monster" that inhabits this scenic, wide stretch of the Mississippi River.
Legend has it that the Dakota Indians who lived in the area refused to travel on Lake Pepin in birch-bark canoes because large creatures would puncture the thin skin of those crafts.
So in an effort to solve the mystery once and for all - and drum up a little extra tourism at the same time - the Lake City (Minn.) Tourism Bureau recently offered a $50,000 reward to anyone who presents indisputable proof that Pepie is real.