The Poplar River flows through northeastern Montana's Hi-Line country on the Fort Peck Indian Reservation. The river holds walleye, northern pike, sauger, and channel catfish. Fishing access requires tribal permits from the Fort Peck Tribes. This is prairie river fishing very different from Montana's famous trout streams. The river eventually joins the Missouri near Poplar. Spring through fall provides the fishing season, with walleye and pike most active in cooler months.