Flowing from the alpine heights of Cucamonga Peak and the Cucamonga Wilderness, the Middle Fork tumbles down a rugged and scenic canyon over several waterfalls. The Lytle Creek drainage defines the east end of the San Gabriel Mountains.
The Middle Fork Trail is one of the least used scenic access routes to the Cucamonga Wilderness. But the lower portion of the creek is a popular water play and angling destination for thousands of summer visitors. Trails of the Angeles describes the Cucamonga Wilderness and Middle Fork Canyon as “one of the few islands of subalpine wilderness left in southern California.”
The stream supports a naturally reproducing rainbow trout population prized by anglers. The upper canyon is part of an area of high ecological significance that is home to regionally significant populations of Nelson’s bighorn sheep and yellow warbler, as well as the recently discovered San Gabriel Mountain salamander.
The word “Cucamonga” is derived from the Gabrieleno kukamonga band of Indians.