Mother nature can trick you, no matter how smart you are. My degree is in Water Resources Engineering. Most dams are designed on a basis of being able to handle maximum probable storms, with accepted standard practices for determining the maximum possible runoff for the dam's drainage area. The tricky part of designing dams that are on huge drainages is often being able to design emergency spillways that can handle maximum runoff without taking away from storage capacity. Every dam is totally unique in its design. The Corps' job of balancing releases from the many reservoirs in a drainage would not be a particularly difficult process, if not for the unpredictability of Mother Nature (we are in the wettest May on record).
Many years ago, Clark Canyon Reservoir (upper reaches of the Missouri) in Montana experienced rainfall that was much higher than the calculated maximum probable storm. The water rose to the point that water just barely topped the dam. Towns below were evacuated. The dam held, but there was a huge outcry against the BOR. The next year, the pool was lowered quite a lot to make sure that the dam would not be threatened again. Unfortunately Mother Nature sent a record drought that lasted four years. The irrigators were screaming because their "dependable" water supply was gone, and their crops suffered. The fishermen were screaming because the river was nearly dry during the non-irrigation season. Boaters were screaming because the lake was not boat-accessible. The BOR took a tremendous amount of heat. In hindsight, they should not have lowered the pool so much.
My conclusion is that somebody needs to develop an accurate crystal ball.