Kathleen Quinlan (The River Why, Apollo 13) Fly Fishing in Idaho at Three Rivers Ranch. For over thirty seven years, Three Rivers Ranch has been providing outstanding service to fly fishermen from all over the world. Nestled in the quiet town of Warm River, in Southeastern Idaho, the ranch is surrounded by enormous pines, brilliant colored aspens and three enticing rivers, all within walking distance from the front step of your cabin. We are licensed on an honor roll of rivers in Idaho, Montana, and Yellowstone National Park including the Madison, Yellowstone, Henry’s Fork and South Fork of the Snake River. A fly fisherman’s dream come true!