I sympathize with the tragedy.
But people need to take responsibility for themselves and their own protection, or we might as well forfeit access to everything. You do not have a right to be forewarned of every natural hazard when you step off the pavement. What used to be a courtesy, provided by the government, is now being demanded as a RIGHT to be warned of all dangers.
If a bridge the forest service maintained collapsed and killed someone, they would be negligent.
Just because they did not warn sufficiently that natural hazards existed in the outdoors, is a bit more of a stretch, and perpetuates the problem that most americans wrongfully expect the great outdoors to be packaged to them as safe, convenient, entertainment.