The secret's out: Tons of water in Oregon's Cascades The most valuable resource in the national forests atop the Oregon Cascades may not be the timber and recreation spots they're known for, but something else that's largely invisible: water. Scientists from the U.S. Forest Service and Oregon State University have in recent years quietly realized that the high Cascades in Oregon and far Northern California contain an immense subterranean reservoir about as large as the biggest man-made reservoirs in the country. The secret stockpile stores close to seven years' worth of Oregon rain and snow and is likely to become increasingly precious, even priceless, as population and climate add pressure to water supplies. The reservoir hides within young volcanic rock -- less than 1 million years old -- in the highest reaches of the Cascades. The rock is so full of cracks and fissures it forms a kind of vast geological sponge. Heavy rain and snow falling on the rock percolate into the sponge, like a river filling a reservoir....