Hot springs near Mammoth Lakes, CA

Mammoth Lakes sits on the eastern slope of the Sierra Nevada at the western edge of the Long Valley Caldera, a volcanic depression the U.S. Geological Survey dates to an eruption about 760,000 years ago and still monitors. The thermal springs of the caldera lie east and southeast of town, in the valley of Hot Creek and the open country around Lake Crowley, on land managed by the Inyo National Forest and the Bureau of Land Management's Bishop Field Office. U.S. 395 runs north toward Mono Lake and Bridgeport and south down the Owens Valley toward Bishop. At the Hot Creek Geological Site, a Forest Service order bars entry within 10 feet of the creek through December 31, 2026.

Several Sierra crossings close in winter. Caltrans closes State Route 120 over Tioga Pass when Yosemite National Park closes Tioga Road, along with State Route 108 over Sonora Pass and State Route 89 over Monitor Pass farther north. State Route 203 beyond Mammoth Lakes typically closes from early November into late May or June. During storms, Caltrans posts chain controls on U.S. 395 and State Route 203, and the Caltrans QuickMap shows current restrictions.