Mackay Reservoir Campground — Sawtooth National Forest

Mackay Reservoir Campground sits along the eastern shore of Mackay Reservoir on the Big Lost River, managed by Sawtooth National Forest out of the Lost River Ranger District. It’s a no-frills developed site — vault toilets, fire rings, picnic tables — with enough elbow room that you won’t feel like you’re in a parking lot. The reservoir draws fishing pressure in summer, but overland rigs running the Pioneer Mountains Scenic Byway use this as a natural staging point before heading north into Copper Basin. Elevation keeps the bugs manageable early season and the nights cold even in July.

Access is paved right to the campground via US-93 north of Mackay — any rig can make it. The sites are first-come, first-served. Water availability varies by year depending on reservoir levels; confirm before counting on it. This is your last reliable developed camp before things get remote heading into the Pioneers.

Big Lost River basecamp before the Pioneers