Dry Falls and the Grand Cooley

Some years ago in my USAF life I spent several short stays at Fairchild AFB in Spokane WA!  During one of those trips I had some time off and myself and coworker drove west.  I remembered two significant things from that day trip – Grand Cooley Dam  and a magnificent 1,000 ft. deep gorge that was very wide! Since we have been out west I have been looking for that gorge.  My coworker, Lenore, who we spent last Thanksgiving with doesn't remember the gorge!  BJ is beginning to think I am crazy – so what's new! 

At any rate while at Fairchild AFB on this trip BJ and I took a day trip out to Grand Coulee Dam and I kept asking around and finally found Dry Falls!  It was just as magnificent and they had expanded the roadside pull-off from just a spot for 3 or 4 cars max to a small State park with a visitors center and educational displays around the edge of the parking lot looking down into the gorge.  And, the geological history behind this gorge is really interesting.

Dry Falls across the center of the pic. Imagine a wall of water  3 times as high as Nigrara Falls and 3 miles wide rushing over it at 65+ mph!

The first picture is from the parking lot looking across the 900 ft. gorge to the Dry Falls.  During the last several thousand years of the last glaciation of the North American continent a large ice dam would form periodically across a valley near Missoula MT.  This ice damn was a thousand feet high and Lake Missoula formed behind it.  The lake had half as much water as in Lake Michigan!  Eventually the water eroded the ice dam and when it gave way the water rushed toward the Pacific scouring the land as it went.  Another smaller, but still large dam on the Upper Columbia River Basin sometimes was also a factor that increased the water flow. 

The gorges formed by these massive floods are called Coulees and Grand Coulee is the largest of them all.  Thus the name of the dam built across the Grand Coulee.  Debris included boulders as big as houses and anything else in its path!  Including soil.  When it got to the mouth of the Columbia River, mountains on each side of the mouth forced water to back up in the valleys behind the mountains! When the flow slowed, a lot of the sediment dropped out.  In the case of the Willamette Valley running north-south from Portland to Eugene the deposited soil created a rich, fertile valley that today is a cornucopia of produce!

Banks Lake, the irrigation reservoir

Back to Dry Falls! When the water from Lake Missoula reached what we call Dry Falls it was moving along at 60+ mph and was about 3 miles wide and nearly 1,000 feet high.  Geologist today estimate that flow had more water then all the rivers of the world today!  Dry Falls was originally 20 miles downstream from where it is today.  They estimate it took Lake Missoula about 2 weeks to drain.  That is a lot of water quickly moving across the land! The force of the water over the hundreds of time this happened carved the rock under the falls and when it collapsed the new edge was further back upstream! 

Grand Coulee dam

Several miles south of Dry Falls at Coulee City a dam has been built that backs the water up into a reservoir that reaches north nearly to Grand Coulee damn.  However, this is an irrigations reservoir only and can be replenished by pumping water up to it from the reservoir behind the Grand Coulee dam if necessary.  Interestingly, the pumps can become generators if the reservoir becomes too full, water can be drained  from it thru the pumps which will generate electricity as water is moved from this reservoir (Banks Lake) to the much larger reservoir behind Grand Coulee dam.  

This was the addition that doubled its elec generation capacity, added in 70's

Us waiting for the light show!

In the evening they had a laser light show at 10 PM.  They projected multicolored line drawings on the white water flow of the dam and gave you the history of the Columbia River Basin from ancient times to today.  We had seen/read most of the history in the Visitors Center and other displays so it was not that interesting to us, but if Reagan and Addison were with us that would be different!

Always at home no matter where we are!