As the river flows south, sea level elevation decreases, causing the datums to drop. Without that drop in the datum point, river levels would reach very low numbers.
“The datum gets lower as you go downstream because otherwise you would definitely get into those negative numbers,” Stiman said.
Understanding all the mathematical information that goes into managing the river is not for the faint of heart, according to Mueller. It is a complex process that takes years of training and practice to learn.
However, many river enthusiasts become frustrated with the constant changes in water levels on the Mississippi and criticize the Corps of Engineers for those changes.
Iowa DNR Mississippi Wildlife Biologist Mike Griffin has heard a number of those complaints from avid fishermen and recreational boaters.
“People think the Corps of Engineers can just snap their fingers and take water away or add water when they need it, but that is simply not the case,” Griffin said.
What the Corps of Engineers can control, is a 9-foot channel between each lock, ensuring safe and effective commercial travel along the Mississippi River.
“Mother Nature pretty much dictates what the water does; we just try to control that 9 foot channel,” Mueller said.