Trout are plentiful but elusive in the fast-flowing Green River in western Wyoming. Anglers from big cities on the West and East Coasts arrive every summer by private jet to stay at rustic ranches in the shadow of the snow-capped Wind River Mountains. They rise early to cast fanciful, hand-tied flies into the clear emerald water in hopes of hooking an inquisitive cutthroat. Fishing was not what drew mountain men, Native American Indians and traders to the lush Green River Valley nearly 200 years ago....