Originally Posted by crabbydan
Just wondering why they keep swift so low in winter when we have some much water down here during this time? The cowlitz is high, as is many others. Just wondering.
The epic flood of 1996 occurred in mid-February. The Pacific Northwest can get amazing accumulations of snow in both normal and abnormal years. If that snow is wet when it falls and builds up there is a lot of water stored in the mountains. Put this together with a "Pineapple Express" that can melt that snow in hours and we have a flood that needs a buffer before it hits populated areas. The reservoirs are the "sponge" that absorbs the shock of warm air and rain hitting mountains full of snow.
I looked at the video of the flood that we bought at the time and Willamette Falls looked like a big riffle with boat houses and homes going over but remaining intact. Impressive.
They calculate the snowpack that will be needed to fill the reservoirs for summer levels then spill water to keep enough room to accommodate the water in normal high runoff years. With a big snowpack and an Express there is not enough cushion to handle it all. Flood control is much more important to more people than is summer recreation. Without those reservoirs winter and early spring in the Valley would be much more interesting. Good Question!