Missouri River dams

It's a bit confusing to try to follow information about what is going on upstream from my house. I always prefer to have a visual, so I "borrowed" this picture from Wikipedia to show the location of the six major dams affecting water levels near my house:

All of these dams will be releasing unprecedented volumes of water by mid-June. To give you an example, I will use Gavins Point, as it is the lowest dam along the river system upstream from me. According to the Army Corps of Engineers website, the record volume of water released by this dam was 70,000 cfs (cubic feet per second) in 1997. On June 4 (2 days ago), the volume going through the spillway was 92,900 cfs. This will be increased to 150,000 cfs by the middle of the month, and that volume will be sustained for the rest of the summer. As you can see, that is more than twice the maximum volume ever released by this dam (in operation since 1955).

How can a small dike just down the road possibly hold back something like that?