big-lost-main-stem

Big Lost River Main Stem is a stretch on Big Lost River, Idaho.

Also called Main Lost and Main Big Lost River.

It is fishable.

From the confluence of the North and East Forks down to Mackay Reservoir. Flywaters calls it the second section, the main stem below the forks: tricky wading, fewer fish, easy access. Fly Fish Food reports the river above the reservoir fishing best below the North Fork confluence. No source gives it a proper name beyond the Main Lost.

It is upstream of Mackay Reservoir.

Sourced from 2 sites.

Sources: flyfishfood.com (retrieved 2026-10-29) and flywaters.com (retrieved 2026-10-29).

Access, closures and rules change; check with the state agency before you go.