Saucer shape in city of Cottage Grove, MN, seen for 5 minutes

It was in September weekend of 1979 and I was away on a fishing trip to northern minnesota, when I got home my wife said she had something to tell me and I shouldn’t laugh at her.
My wife is a strong german farm girl and not at all prone to making up tales.
 So she tells me that on Saturday evening she was coming home after visiting my folks. She was traveling east and she when topped the hill on 80th  near the police station in Cottage Grove. She notices a saucer shaped object hovering  over the houses off to the right or south. I questioned her about that part because there is a water tower about a ¼ mile east and south  of the police station, but she said she could clearly see the water tower and the ufo was closer to her and further south a little. She said she watched it til she came abreast of it and continued on towards home feeling spooked and not wanting to stop with our three kids sleeping in the back seat. When she got to keats ave about a mile or so further east she did stop the car and got out to look at it, as it was still in approximately the same position. So she had watched it for about 5 minutes and was as close to it as a half a city block.
 So our kids are grown up and married and my oldest girl and her husband were over for supper one night many years later. He started  telling us a story about his 13th birthday party and how a tiny object no bigger than a foot in diameter flew right between him and a friend while they were playing in the yard  My son-in-law lived right about where my wife saw the ufo and it was the same weekend in Sept. 1979  We have thought about filing a report or calling the police but not wanting to get the notoriety.
 My wife describes it as about 30-40 ft in diameter and about 8-10 ft tall at the center, she says this because she thought that it was as wide as the houses under it. She says it was about 50 ft in the air.
Witness indicates that the date of the incident is approximate.  PD