If you place the emphasis on WERE on the water, this story complies. My hunting partner at the time and I tracked-down an entire rig of Toledo decoys that went missing from Munuscong Bay waters. Their owner was a guy who moved into the area from Ohio post-purchase of a cabin rental/fishing access resort on the southern margin of the bay. He decided to start guiding his second year in Michigan. The guide law definition read that you needed a commercial guide's license to take hunters/fishers out in your boat, so he was operating illegally. I got to know him relatively well since I used his ice-taxi service to fish the southern bay for walleye during winter. There is an U.S. Army Corps of Engineers quarters barge built in the early 1900s moored on the north shore of the bay, that serves as a duck club for a group of Sault Ste. Marie businessmen. A turf war developed over a piece of water know as "the slot". When he began leaving his decoys set-up overnight here (also illegal under Michigan waterfowling laws), they were eventually stolen. Turned-out the Merganser "crew" hired a local waterman who routinely operated outside the law, encouraging him to remove the decoys...for a case of whiskey.
My duck hunting partner was a lawyer and local, with "connections" on both sides of the law.
During those years, it was not uncommon to hear an inboard motor rev-up and run screaming across the open waters of the river at night go land on the U.S. side, when we were out sampling on the upper 42miles of water. I opt to word the experience as "hear", since the boats ran without lights. Lots of booze and cigarettes trafficked into the U.S. via this route in that era. Over four years I never witnessed or heard of any enforcement patrols other than around the locks and harbor area to the north. When I saw what remained of the case of whiskey, the contents were lacking seals.
Four years ago, Steve Lewis and I were hunting the St.Mary's out of a nice log cabin he rented that sat on a point on Neebish Island below the Rock Cut. We were done for the day, so after cleaning birds and rearranging our gear and boat contents, we were doing some housekeeping on Sam's camp. When I looked out through the thin screen of cedars that separate the cabin and outbuildings (sauna and fish frying shack, outhouse, and wood working shop) from the river, a nice shiny new(er) U.S. Boarder Patrol boat came sliding down the navigation channel, armed to the teeth and coasting along, sporting four 250hp Verados on its transom! Post September 11th attacks, things have apparently changed.