Watch this video of Oregon’s aptly named Lost Lake disappear! Every spring, Lost Lake turns into a peaceful meadow as it rapidly drains through a six-foot diameter hole in its lake bottom. Early next spring, the lake will fill again with snowmelt which accumulates faster than the hole can drain.
The hole is a lava tube which forms when lava cools around the edges of river of molten rock. When the lava drains away, it can leave an empty space as it did at Lost Lake. The Cascade Mountain Range was formed largely via volcanic activity and so boasts many similar tubes throughout the range. Once in the hole, the water flows through the porous, volcanic rock and then into an aquifer before finally emerging at nearby springs.
Though many parts of the northwest are experiencing drought, Lost Lake has been more fortunate and is not suffering from severely decreased snow melt.