Saturday, August 27, 2011

Pierre SD Flooding from Lake Oahe

Lake Oahe is a huge lake resulting from one of the largest earthen dams in the world which backs up the Missouri River over 200 miles. Located just above Pierre, SD, the lake experienced terrific snow runoff last spring and as a result, filled to capacity -- and then some.

As a result, The Corps of Engineers had to release unprecedented amounts of water starting in May of 2011 and which caused terrible flooding of the Pierre area as well as further downstream. Rick wanted to check this area out in August after over 3 months of water releases.

This picture is directly below the dam at the powerhouse which generates huge amounts of water. The last time Rick was here, the water was several feet below its current level.

This looks downstream and you can see the trees are actually in the water. The trees are actually on a large levee which usually is several feet above the water. I would guess that the powerhouse river is at least three times as wide as it usually is.

This gives a better view of the powerhouse and you can just see a platform on the left side of the river that seems to be almost floating. This is actually a fishing pier and is usually about 8 to 10 feet above the water -- now it is literally at the water level.

The spillway is located at the other end of the 9,300' long dam with 5 outlets. This was truly impressive with vast volumes of water shooting out of the spillway gates and making large waves in the "stilling basin".

Wow! Prior to this spring, Oahe had released a maximum of about 55,000 cubic feet per minute of water. This spring, that reached a record 160,000 CFM. Now, this is being reduced, but is still at about 130,000 CFM. This was almost scary to stand next too as the roar was very loud and the ground literally shakes. You can get a good idea as to this in the video below.

Next post will focus on the damage done by the flooding and the remarkable preventative efforts that saved many structures.

1 comment:

squawmama said...

Great photos and post!!!!
Have fun