Located on the Colorado River about 30 miles southeast of Las Vegas, Lake Mead is the largest reservoir in the United States. Its formation by the Hoover Dam in 1936 forced the evacuation of several nearby towns, most notably St. Thomas, Nevada. The ruins of St. Thomas are occasionally still visible when the lake’s water level is unusually low. At the current water level, the white ring sometimes referred to as a “bathtub” ring caused by mineral deposits is clearly visible in photos of the shoreline. Today, the Lake Mead National Recreation Area offers year-round activities and is especially popular with Las Vegas residents.