Monday, April 02, 2012

Willamette River decides not to flood --this time

Willamette Falls after 3 days of solid rain
The Willamette River crested today after last week's Pacific Northwest downpour.  Three days of steady, heavy rain.  The National Weather Service says that the crest reached 16.28 feet in Portland.  Just about a foot and a half below flood stage, and nothing at all like the Flood of '96, when the river crested at 28.6 feet, surpassing flood stage by a full 10 and a half feet!

But the Flood of '96 was itself dwarfed by the Great Flood of 1861.  The Great Flood completely drowned some townships, including Champoeg, the site of the first organized government of the Oregon Territory.  The Great Flood was so massive that, at its peak, the volume of water flowing in the Willamette River surpassed that of the Mississippi River itself.  The Great Flood is the biggest Willamette River flood in recorded history.

The first Oregonians, the Chinook, the Clackamas, the Long Tom, the Yamhill, who bequeathed their names to the Willamette's tributaries, came here some ten thousand years ago.  In those days, before recorded history the Willamette still flooded, but there were backwaters and sloughs to absorb the floods so they wreaked less destruction on the valley floor.  The floods were less severe in those days before civilization channeled and deepened the river.

But a few thousand years before mankind first came to Oregon were the great floods.  These were the floods  that came from the north and east.  They were caused by the melt of retreating glaciers.  The first and greatest was the Lake Missoula Flood which came when a glacial dam broke open and unleashed an entire ocean of water through the Columbia Gorge, scouring the earth.  Over the next few thousands of years, scores of floods literally scrubbed eastern Washington of its topsoil and deposited it in the Willamette Valley. The land still bears the scars of those great washings.

Clear demonstration of two truths, I suppose:  the Willamette River is a flood-prone river.  And recorded history really isn't much time at all.

I'll tell you this, though:  the water made an impressive sight.  Roaring and rioting over Willamette Falls.

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