The Big Lost River, outside of Sun Valley, offers two amazing experiences ranging from true wilderness fly fishing on freestone tributaries in the high desert to fishing the cottonwood-forest tailwater section below Mackay Reservoir. This wonderful upper system is made up of many different rivers including, Summit Creek, North Fork of the Lost River, East Fork of the Lost River, Wildhorse Creek, Star Hope Creek and the upper main Big Lost River. The lower Big Lost River is a tailwater fishery supporting a very healthy rainbow trout population. Outside of late May through at least mid-July, when the river is usually too high to fish, the lower Big Lost river is an all year fishery--it's open to fishing 12 months of the year. Add in a few seasonal spring creeks plus the reservoir and it becomes clear that there is endless fly-fishing opportunity to be found from 45 minutes to an hour east of the Sun Valley Lodge.
A variety of trout live in the mountainous stretches of the upper waters and it is not uncommon for guests to try for the “Lost River Slam” which includes catching one each of Rainbow Trout, West Slope Cutthroat Trout, Snake River Fine Spotted Cutthroat Trout, Brook Trout, Cuttbow, and Mountain Whitefish in a single day! That is six species of wild fish in one river! The high-country nature of the upper Lost River drainage makes it very user friendly for all skill levels of fly angler, it also makes it a great place to relax, breathe fresh air and listen to nothing but the sound of wind, water and maybe the occasional laughter of a happy fisherman. Large flies are the norm, and fish from 8 to 20 inches are common.
The Lower Big Lost River is a tailwater emitting from Mackay Reservoir. This fishery holds some great specimens of Rainbow trout. They grow large and fight hard due to the nutrient rich and very cold water coming from the bottom of the dam. Access is somewhat limited and nymphing is the norm more often than not, although excellent Midge, Crane Fly, PMD, Trico and Baetis hatches and spinner falls do occur. The experienced fly angler is going to find this an exciting place to cast flies and challenge big fish.
The wide variety of water types on the Big Lost allows Picabo Anlger to guide absolute beginners as well as seasoned pros on these watershed. Due to the distance and dirt roads that keep the Lost River system quiet, we only offer ¾ day and full day trips to the upper Lost River area, and only full day trips to the Lower Big Lost River.
USGS water flow gauge for the Big Lost River below the Mackay Reservoir: HERE
Guided Fly Fishing Rates & Info: HERE