I can think of an example in which federal wildlife biologist have tried to cut off human access. A few years ago, the Pacific Northwest Trail organization wanted to route the trail up Swift Creek near Baker Lake to reach Artist's Point. There is a rough existing trail that follows the creek, however the lack of a bridge at the crossing makes it very dangerous to cross except at low water.
PNT asked the Forest Service to build a bridge. FS asked a wildlife biologist to review the plan. He put a big circle around the area saying it was "grizzly habitat". He didn't mean there were actually grizzlies there, just that due to it's relative isolation, it would make good habitat. On the basis of that summary judgment, the FS decided not to build the bridge, and the PNW was forced to reroute to a less desireable alternative.