At three quarters the size of Rhode Island, the Weminuche Wilderness is the largest Wilderness area in Colorado at 499,771 acres. It is part of the National Wilderness Preservation System, established by the Wilderness Act of 1964 to "secure for the American people of present and future generations the benefits of an enduring resource of wilderness." The Weminuche was designated by Congress in 1975, and expanded by the Colorado Wilderness Acts of 1980 and 1993.

The Weminuche spans the Continental Divide, North America's geological backbone, with its headwaters diverted to both the Pacific and Atlantic oceans. Eolus, Sunlight, and Windom peaks rise above 14,000 feet, while many others reach above 13,000 feet. With an average elevation of 10,000 feet above sea level, the Weminuche is rugged country, but its ecosystems are fragile.

The Weminuche protects the headwaters of both the Rio Grande River and the San Juan River (which then runs into the Colorado River) providing clear drinking water to millions of people.