Gratiot is a street in the Detroit area. You're not from here. It was a Drivein up until the 80' Yes its a waterfall and the screen was on the other side.
oh, drive -in movie! I worked at a drive-in movie in Seattle in 68. I bought an NOS 340 6pak setup from Gratiot, or Couch back in the mid 70's. $300 sticks in my mind.