Lake Powell is a man-made reservoir on the Colorado River, straddling the border between Utah and Arizona. It is the second largest man-made reservoir in the United States behind Lake Mead, storing 30 km³ of water when full. Lake Powell was created by the flooding of Glen Canyon by the controversial Glen Canyon Dam, which also led to the creation of Glen Canyon National Recreation Area, a popular summer destination. The reservoir is named for explorer John Wesley Powell, a one-armed American Civil War veteran who explored the river via three wooden boats in 1869. In 1972, Glen Canyon National Recreation Area was established. It is public land managed by the National Park Service, and available to the public for recreational purposes.