Alturas Lake is a freshwater lake located on the northern slope of Bald Eagle Peak, in King County, Washington.

[3] Alturas Lake drains North towards Tonga Ridge and into the East Fork of the Foss River.

[4] Access to Alturas Lake is through Necklace Valley Trail #1062 off Foss River Road (Forest Service Road #68), which exits US Highway 2 approximately at mile marker 50.5, just east of the Skykomish Ranger Station.

The trail ends in Jade Lake further East from Alturas Lake.

Self-issued Alpine Lake Wilderness permit required for transit within the Necklace Valley area.