The water levels on major Midwestern rivers are a key issue for farmers, whether they threaten flooding or present situations like last fall when low water levels on the Mississippi and Missouri rivers threatened the movement of grain and other supplies.
That concern has been eased over the winter. University of Missouri ag economist Ray Massey says this has helped with worries about getting crop inputs where they are needed this year.
“The rivers are flowing a little better, the logistics are flowing a little better,” he says.
Now, the typical spring concern of whether any rivers will flood has come into focus.
Spray paint on a rural highway in Saline County, Missouri, shows the high water mark for the 2019 flood.
The National Weather Service provides flooding outlooks for the major rivers. Kevin Low, service coordination hydrologist, works at the Missouri Basin River Forecast Center at Pleasant Hill, Missouri. He says in the early spring, the outlook for the Missouri River basin starts with looking at three factors — “snowpack in the mountains, snowpack on the plains and current stream flow.”
Low and others put that information into computer models to create the current picture.
“We attempt to simulate what is going on right now, to the best of our ability,” he says.
Once they have that current picture, Low says the NWS takes precipitation and temperature information from the last 30 years, and pairs that data with the current information to create an “ensemble” projection of what water levels might look like this spring.
According to the National Weather Service’s long-range flood outlooks, the biggest flood risks — the gauges with more than a 50% chance of “major long-range flood risk” — are located in southeast South Dakota and then along the Mississippi River between Iowa and Illinois. That stretch of the Mississippi sits downstream from the major snowpack in Minnesota, in areas less-affected or not affected by drought.
Several gauges along the Mississippi River between northern Missouri and Illinois, as well as several tributary rivers in Missouri, have a more than 50% chance of “moderate long-range flood risk.”
People can go to water.weather.gov for a full map of flood risks at each river gauge.
Low says recent precipitation has changed the Missouri River basin flood outlook.
“The story has kind of changed over the last month or so,” he says.
He says the Missouri basin is in its third year when large parts of it have experienced drought. However, the basin recently went below 50% in drought. Drought was a big factor in early 2023 river level outlooks, however the area in drought has since shrunk. Now, the heavy snowpack in the Upper Midwest has flood forecasters’ attention.
Low says the “abnormally large snowpack” in the Dakotas has already contributed to some flooding there and in northwest Iowa. Also, the cold weather in the Upper Midwest has meant the snowpack has stuck around longer than normal, and he says the longer it stays around, the higher the risk of it melting rapidly due to quickly warming temperatures. This could result in more rapid runoff.
Heavy snowpack in the Upper Midwest has flood forecasters’ attention.
Speaking the first week of April, Low says the week after Easter should help get some of the snow melted without putting too much water into river systems.
“Easter week is supposed to be warmer than normal for the entire basin,” he says. “That’s a good thing because it’ll help us melt some of this snow, and no precipitation to add fuel to the fire.”
Soil saturation is also important for flood outlooks. Soils are more saturated in Missouri and Illinois, where almost all or all of those states are drought free, but much of Iowa remains in drought. The ability of soil to soak up rainfall can determine how much flooding occurs.
Low says some of Missouri’s smaller rivers could see fairly typical, modest flooding this spring due to the saturated soils in the state, but he describes conditions in the state as normal.
“Those creeks and streams that get up, we’d expect them to do that,” he says.
