Clip: Season 25 Episode 2506 | 6m 58s
South Prairie is a mysterious lake in the Gifford Pinchot National Forest that appears each spring and disappears each summer. We set out with a Forest Service botonist 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 farthest west aspen groves in Washington.
Aired: 11/14/13Video has closed captioning.