The Great Salt Lake in Utah does not have a way for water to drain out. It sits in a bowl, surrounded by mountains all around. When the spring thaw in those mountains fills it up with water that extra water floods the extensive flat areas between the lake and the mountains. Quickly though, the water evaporates, leaving salt covering the flats. Here we see a salt flat covered with water. It is not very deep, you could probably wade all the way across it. The highway they built across here is elevated to keep it dry.