Water: assume none. The Forest Service page and recreation.gov contradict each other on drinking water here, so bring everything you plan to drink.
Nights run cold up here - pack warm layers even in July.
What you get at Mirror Lake is elevation and access in one place: 10,200 feet, a small boat ramp and picnic area on the shore, and trailheads for Bald Mountain and Fehr Lake within a couple of miles. The loops are dirt with no hookups, so towing anything large is a chore. Motors are banned on the lake, which keeps mornings quiet for a canoe. A host sells firewood on site.
Tip: Freezing nights any month. Stocked weekly, bring the ultralight.
Out the tent door: Mirror Lake (Uintas) (Fishing, 0 mi) · Fehr Lake Trail (Hike, 0 mi) · Bald Mountain (Hike, 1 mi) · Lofty Lake Loop (Hike, 2 mi)