Another story shared with permission. Both my Mother and Aunt worked at the haunted house that used to be held in The Old Mill, they also helped with a movie filmed there, Teen Alien. When they worked in the haunted house they were most often what is referred to as a "plant". The scared girl who gets grabbed by the monster and dragged into a closet, the "volunteer" who gets cut up on the operating table of the mad doctor etc.
They told me several stories of odd things happening, both during the hours the place was open and when it was closed.
One year as part of a scene a friend brought his dog along and many times the dog could be found staring into a dark corner growling at nothing anyone else could see. My Aunt was touched several times when no one else was near.
My mom told me of one time a bunch of kids were exclaiming over how realistic the hanged man in the upper room looked. There was no hanged man in any of the scenes.
My Aunt told me that while they were doing editing on the film they discovered many odd sounds, mists and shadows that were not supposed to be there, including the shadow of the hanged man and someone whispering my aunts name in an empty room.
Unfortunately I never personally got a chance to go to this place but I wish I had.
As for the history of The Old Mill you can just type it into a search browser, add Utah to it and get tons of information on it.