It is formed by a dam at the headwaters of Mud Creek, tributary to the Salmon River.

A log road across marshes allowed immigrants to pass to Summit Meadow, which was a toll station 1866—1870.

Adjacent Trillium Lake Campground is administered by the Zigzag Ranger District of the Mount Hood National Forest.

The large campground features a seasonal boat ramp and wheelchair-accessible floating dock.

[6] The lake is a very popular Nordic skiing destination from a trailhead across U.S. Route 26 from Snow Bunny.