Zzyzx, formerly Soda Springs, is an unincorporated place in San Bernardino County, California, United States, within the boundaries of the Mojave National Preserve, managed by the National Park Service (NPS), an agency of the U.S. Department of Interior, as public land. It is the former site of the Zzyzx Mineral Springs and Health Spa, and now the site of the Desert Studies Center and is centered around the former right of way of the Tonopah and Tidewater Railroad. The site is also the location of Lake Tuendae, originally part of the spa, and now a refuge habitat of the endangered Mohave tui chub.