What is the largest lake in southwest corner?

The largest lake in the southwest corner of the contiguous United States is Lake Mead. It is located on the Colorado River, on the border between Arizona and Nevada. Lake Mead is the largest reservoir in the United States by volume and the fourth largest in the world. It has a surface area of 248 square miles and a maximum depth of 532 feet. Lake Mead was created in 1935 when the Hoover Dam was built.