Exploring Southwest Washington’s disappearing lake

South Prairie is a mysterious 85-acre lake in the Gifford Pinchot National Forest of Southwest Washington. It appears each spring, and disappears each summer. What's the secret of this unique geologic phenomenon? We set out with a Forest Service botanist to paddle and hike this geologic wonder, trying to learn what’s behind this phenomenon. The prairie is home to the world’s largest-known population of a rare iris and some of the westernmost aspen groves in Washington. This story first aired on Nov. 14, 2013.