Season- Memorial Day weekend- March 31st


The Big Lost River

The Big Lost river system epitomizes the mountain fly-fishing experience. A very secluded and quality fishery, ‘The Lost’ is undeveloped and surrounded by spectacular mountains, abundant wildlife, and diverse wildflowers. Just over Trail Creek Pass (east of Ketchum) the Lost originates on the remote east slopes of the Pioneer Mountains and works its way into the Big Lost Valley.  From the upper freestone reaches of Copper Basin, Wildhorse Creek, and the North and East Fork tributaries all the way to its treasured tail waters below Mackay Reservoir, the Big Lost really has it all.

The Lost tends to yield uncommonly large trout relative to the size of river. The largest fish (rainbows) will be found below Mackay Reservoir and will be found up to and beyond 25 inches. Above the reservoir twenty-inch fish (rainbow and kokanee)  are not uncommon but the 14-17 inch range is the norm. In the upper tributaries, 11-15 inch rainbow, cutthroat and brook trout are most common, but bigger fish are up there.

Excellent bug life exists on this remote river. Above the reservoir the hatches commonly run parallel with or just a little behind the upper Big Wood River. This means a smorgasbourd of dry fly action for fly-fishermen. Stimulators, Hoppers, various Mayflies, Caddis, Stoneflies and other attractor patterns (to name a few) can be successful. Below the reservoir a slightly more technical fishery emerges where sight nymphing is common. In addition, various dry-fly opportunities (Salmon flies, Cicadas, Mayflies and Hoppers) present themselves throughout the summer.

If the environment or the adventure is just as important as the fly-fishing, the Big Lost is for you. Even a slow day on the Lost is a memorable experience. This vast river system is located in remote country. It winds through private, BLM, and National Forest land. To experience the Lost safely, efficiently, and effectively hire a Sun Valley Mountain Guides’ guide for a Full Day fly-fishing outing. It will definitely be an experience to remember!

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