"Grey Reef is a very forgiving place to wade fish as the river bottom is not difficult to walk on. The bottom of the river is a variety of sand, gravel, cobble and silt.
While Grey Reef has plenty of public access, most of it flows through private land.... In Wyoming the bottom of the river belongs to the land owner. Wading, anchoring or even beaching your boat is considered trespassing in Wyoming. " http://www.northplatteflyfishing.com/greyreef.php Floating, more expensive, but less hassle and more fish. Rentals and ferrying is available. http://www.northplatteflyfishing.com/miraclemile.php a different streatch entirely. Check out the Casper fly shops on your way through for tips and current river info and hatches. Loads of accomodations/restuarants in the Casper area which thin out fast as you head up toward the fishing.