South Warner Wilderness, Nature reserve in Modoc County, US

South Warner Wilderness is a large protected nature reserve in the Warner Mountains of northeastern California, featuring elevations between 4,800 and 9,900 feet. The landscape includes forested slopes, alpine meadows, and rocky peaks connected by well-maintained trail systems that wind through the terrain.

The U.S. Forest Service first recognized this area as a primitive region in 1931, and the Wilderness Act of 1964 gave it official protected status. This legal designation has kept the landscape largely undeveloped and unchanged since then.

The wilderness lies within Modoc National Forest, and the Forest Service asks visitors to follow Leave No Trace practices to limit human impact. The name Warner comes from the Warner Mountains, the fault-block range the area protects. Fishing is allowed in lakes such as Patterson Lake, which holds a self-sustaining trout population.

The wilderness has 79.2 miles of maintained trails plus about 20 miles of unmaintained paths, reached from eight trailheads and five campgrounds. Pepperdine Trailhead has corrals for horses and stock parties. Hiking is the main activity, with fishing, horseback riding, snowshoeing and cross-country skiing also possible. The Forest Service asks visitors to follow Leave No Trace practices.

The crest of the Warner Mountains divides water flow between two completely different drainage systems that are worlds apart. On one side water flows toward the Sacramento River, while on the other side it feeds alkali lakes of the Great Basin - a geological boundary you can cross while hiking.