The shelf runs for about 500-600 feet in length and comes out about 150 feet from shore. He was probably 100 feet or so along the shelf (but he was to far from shore to be on it) and there were 2 power boats further along the shelf, one near the far end and another closer to the center. Both were in tight to shore. As I said I have anchored here hundreds of times. Once you get off that shelf the next feasible place to anchor is in 75 feet of water near the outflow of the river about 700 meters south of this location. This spot is close to a provincial park that fills with yahoos on weekends who pour gasoline onto their bonfires during fire bans and burn down the outhouses. I wouldnt anchor in this location overnight and have never seen anyone anchor there for more than a few hours.
I guess we could have tied the stern off to shore to get rid of our swing but given the way the tide will move through there I think that invites more risk than you run doing as we did.