The volcanic roots of Oregon's Mount Hood National Forest become evident each year when the mysterious Lost Lake vanishes. Near the Hoodoo Ski Area, the water of Lost Lake escapes through a hole on the north shore like water down a drain.

Once called "Kwoneksamach," or "unknown" by Native Americans, the "drain" next to Lost Lake is the mouth of an open lava tube. The hidden exit the lake's water takes each year has stumped scientists, but many think that it is held in an aquifer underground until the next season.

Each year water from the lake flows through the ancient lava tube and is then replaced by creek water. However, as winter comes and the snowpack of the mountains freezes, the creeks dry out. This causes the lake's level to drop until it is empty, leaving a meadow in its place.

Jude McHugh, a spokeswoman with the Willamette National Forest, says that the hole, six feet across, has been there as long as anyone can remember.

"It fills up in the winter, when input exceeds the rate of draining, and then it goes dry and it's a meadow," McHugh says. Ryan Brennecke, a journalist from The Bend Bulletin, uploaded the YouTube video here that shows the water of Lost Lake draining through the open lava tube.

Lava tubes are conduit structures that drain lava from an erupting volcano. Lava that is nearest to the surface cools first, but closer to the interior the lava continues to flow. This is what creates the initial tube structure which are common in the region. After the lava has stopped, these tunnels cool and harden. The result is a series of tunnel- and cave-like structures that open to the surface and carry water between the lake and, perhaps, an aquifer. Any such aquifer would probably glean its water through the porous lava rock above, and would feed the waterways on both sides of the Cascade Mountains.

The aquifer theory is supported by the contrast between the Lost Lake area and other drought-plagued regions. Oregon, like California, has had a low-snow winter. Some counties in Oregon are experiencing drought, but Lost Lake's Linn County is not among them. Nearby Fish Lake has similar lava tubes and also experiences a seasonal cycle.

"Eventually that same water pops up out and I'm having it in my morning coffee right now," McHugh says.

Apparently some local people have attempted to stop the draining of Lost Lake in the past, using car parts and other refuse to act as a plug for the lake. McHugh clarifies that such attempts are discouraged:

"If anyone was ever successful at plugging it - which we're not sure they could do - it would just result in the lake flooding, and the road; it's an important part of how the road was designed."