While I was back in South Dakota I took a run up to Oahe Dam just outside of Pierre SD. It’s the largest of six reservoirs on the Missouri River. Way back in June water levels on all the dams were at full pool and threatening to overflow emergency spillways.

Snowmelt from record snow levels in the Rocky Mountains and heavy rains in many of the areas draining into the Missouri combined to create a 500 year flood.

The Corp of Engineers, which is responsible for the operation of the dams started releasing water from all the reservoirs in an effort keep the levels in check. They delayed the historic releases to allow downstream residents to prepare with levees, sandbagging and dike reinforcement.

When the releases were at their peak about 220,000 cubic feet per second, that’s roughly 1.3 million gallons per second, were flowing out of six tubes at the base of Oahe Dam. I took this series of three photos to illustrate the size and power of a flow of water of that magnitude. I estimated the tube to be about 16 feet in diameter.

The releases are slowly being reduced now back to normal levels, somewhere around 35,000 cfs. Officials estimate it will be sometime in September before river levels as far south as St. Jo Missouri return to normal.