The Bighorn River earns respect by supporting more than 5,000 brown and rainbow trout per mile. The trout average 16 inches in length, yet there are enough 22- to 24-inch trout in the four- to six-pound range caught each year to establish this as a world-class fishery. The most productive section of the tailwater is the 13 miles below the afterbay, near Fort Smith, to the Bighorn Access. The ratio of browns to rainbows here is about three to two. Above the 600-foot cable at the afterbay, lures, flies and live bait are legal and the creel limit is five trout (no more than one of which may be a rainbow). Below the cable, the limit is five brown trout (one over 18 inches), rainbows are catch-and-release, and only flies and lures are legal. In August, grasshopper patterns and dry flies like Black Caddis draw surface strikes. Spin-fishermen do well with fly/bubble combinations or small spinners and spoons. A resident fishing license is $17; nonresidents pay $15 for two days or $50 for the season. Contact: Bighorn Trout Shop (406-666-2375); Montana Department of Fish, Wildlife and Parks (406-247-2940).