Answer: The situation was "dire" at the Fremont lake bottleneck as mule deer had to pass through an area which was just few hundred yards wide. They were seen walking to and fro along the fence looking for a way to cross that fence.
Explanation:
As the open lands were taken under construction and new barriers were built mule deer were funneled between residential developments and lakes.
They started migrating around 150 miles through Wyoming two times in a year. Their migration took place during winter in Red desert and during summer in Upper Hoback River.
This migration route exposed these animals to all public and private lands, highways, through rivers - which involved crossing of multiple fences. It was these fence that served as dire at the Fremont lake in Wyoming.