The drainage hole is capable of depleting the lake of all its water in the summer season, leaving an arid meadow in its place. The natural phenomenon has been a feature at the Lost Lake in Oregon, US, for as long as people can remember. And it is down to a lava tube - a tunnel-like structure originally created to drain lava from a volcano during an eruption. Jude McHugh, a spokesperson for Williamette National Forest, said, "In Lost Lake, this lava tube collapsed and became the drain hole for that lake."
Ms McHugh suggested that the lake is likely to be constantly draining, but in drier months the rate of draining will exceed the input from precipitation which turns the lake into a meadow. Residents in the area have attempted to fill the hole but their efforts have so far been unsuccessful. But Ms McHugh warned that blocking up the naturally occurring filter could mean the lake is likely to flood, causing problems for nearby roads and infrastructure. She estimates that the water travels through the lava tube and seeps into the subsurface of the porous rocks, before eventually seeping into springs on both sides of the Cascade mountain range. Ms McHugh added, "Eventually the same water pops out and I'm having it in my morning coffee right now."