If you're an avid angler, then you already know: The Au Sable River in Michigan is hands-down one of the best trout streams in the world. This mighty river starts north of Grayling, Michigan, and flows for about 100 miles before emptying into Lake Huron here in Oscoda. It provides excellent opportunities for both novice and experienced fly fishermen to catch a variety of trophy fish, including brown trout, rainbow trout, brook trout, steelhead and salmon.