Dumping at Campgrounds and Flushing Black Water Tank Too

I was just in Grand Teton Park at a campground with 2 dumps. The guy ahead of me was at the first dump. Which was fine, maybe when he got there there was a guy in the 2nd one. The only problem was he had his MH parked in the middle of the road so there was no way past him. So there we sat with an unused dump that we couldn't get to until he was done. And he took his time. Lot's of flushing.