Big Lost River - Lower

About Big Lost River - Lower

The Lower Big Lost River is a tailwater fishery below Mackay Reservoir in Idaho. This section offers a different experience from the freestone tributaries, with nutrient-rich, cold water creating ideal conditions for trout. The river flows through a landscape of cottonwood and aspen forests, with the dramatic peaks of the Lost River Range as a backdrop. Access is somewhat limited due to private land, but public sections are available for anglers to work. The water itself is visually appealing, with clear channels and varied depths that hold sizable fish. The Lower Big Lost River is known for its large and healthy Rainbow Trout, with Brook Trout also present. The cold, consistent water from the reservoir fuels excellent growth. Hatches are frequent, including Stoneflies, Caddis, Pale Morning Duns (PMDs), Blue-Winged Olives (BWOs), Crane Flies, and Tricos. Spinner falls are also common. Nymphing is a primary tactic here, and it's an excellent place to sight nymph for big trout. Consider using patterns like Hare's Ears, Prince Nymphs, or San Juan Worms deep in the runs. As hatches occur, dry fly presentations with Elk Hair Caddis, Parachute Adams, or BWO spinners can be effective. When the fish are looking up, especially during Trico spinner falls in the morning, a well-placed dry fly can bring explosive takes. Work the deeper pools and runs where the current slows, and don't overlook the edges where trout can ambush food. Be prepared for varied light conditions; the best fishing often occurs during the early morning and late afternoon. Respect other anglers sharing the water; give them space and approach fish with stealth.