McKenzie River: The Lava That Made a River Run Clear

The McKenzie River does something unusual. It disappears.

North of the town of McKenzie Bridge, where Highway One Twenty-Six follows the river east into the Willamette National Forest, the valley floor is covered in young, porous lava from eruptions that occurred within the past three thousand years. The Clear Lake lava flow blocked the ancestral McKenzie channel, creating a lake so cold and so clear that the ancient forest drowned beneath it is still standing at the bottom, preserved for nearly three thousand years by the cold water.

Below the lava field, springs emerge from the basalt. The water that percolates through the lava flows comes out filtered and cold and carries the clarity of the rock through which it passed. This filtered water feeds the upper McKenzie, and the result is a river that looks, in certain stretches and certain light, like it is running over glass. It does not run this way because the watershed is undisturbed. It runs this way because of the geology.

The McKenzie has one of the most unusual national fish hatcheries in the country. The McKenzie River hatchery near Leaburg operates a program specifically to maintain the McKenzie summer steelhead, a genetically distinct race of fish whose spawning migration occurs when most steelhead are already heading downstream. The fish adapted to this unusual timing over thousands of years. The hatchery is trying to preserve a genetic clock that could not be rebuilt.

The river trail that runs parallel to Highway One Twenty-Six for twenty-six miles is one of the longest river trails in Oregon, runnable by bicycle or walkable in segments, through an alternating sequence of old growth, lava flow, and waterfall that makes the Willamette National Forest's inner logic, the geology beneath the trees, visibly legible.