Read this morning in the paper that they're expecting the river to rise another 3' - 5'. I've also heard (though I don't know how reliable this is) that Gavins Point Dam has actually moved. It's shifting. If that's true, a collapse is very possible. And if that happens, well...
My parents live about 10 miles northwest of the dam. I was up there over the weekend and we went to the dam to see what the flow looked like. I have been over that dam hundreds of times and other than a whole lot of water coming through the spillways, nothing else seems out of the ordinary.
There have been tons of rumors floating around even in Yankton. One is that they were closing the road over the dam because the dam was shaking. In fact, they have been refurbishing the cranes on top of the dam and the road has been closed Monday - Friday until 5:00pm since before this flooding started and it is open on weekends. It seems, people (just like the media) would love to see a catastrophic failure of the dam. I don't put much weight to any of the rumors floating around.
The dam, unlike levees, was built to hold back a large amount of water. When I viewed the lake it did not seem all that much higher than I have seen it during past springs. In fact, the level of the lake has dropped since they began opening the spillways to the level it is at now. The next dam up, Fort Randal, has been holding at a lower CFS output and they plan to release more from that dam soon since the Lewis and Clark Reservoir has gone down a little.
One of the engineers at the dam goes to my parents church. He said that they do not think the dam is open to the full 150,000 cfs as of saturday. They think they still have a little more before they reach that. He also said that each gate on the spillways is open to about 8 feet.
Below the dam, the river is running high and the corp is working to maintain the banks. There is minimal flooding just below the lake, but the water has begun to back up into Lake Yankton which is a smaller lake just below the dam.
The Dam has turned into a huge tourist attraction up there and there are a lot of cars in the parking lot and along the road following the river. Just walking up to the dam you get dizzy because the water is moving so fast from the spillways. You get soaked just from the over spray and if you are not careful, you will get drenched by rouge waves hitting the wall below the parking lot, as my daughter found out. She was drenched.
So, to make a long story short, In my opinion the dam is fine and will remain so through this event.