Minor spring flooding in forecast for Mississippi, Illinois rivers

Posted: Mar. 13, 2014 9:13 am Updated: Apr. 3, 2014 1:15 pm

Herald-Whig Staff Writer

The National Weather Service says there's a good chance minor flooding will occur along both the upper Mississippi and lower Illinois rivers this spring.

However, the agency's spring flood outlook -- issued last week -- says significant flooding along the Illinois River remains unlikely if normal spring rainfall occurs. Meanwhile, the chances for moderate flooding along the Mississippi remain near the seasonal average.

While the NWS flood outlook appears somewhat encouraging for flood-weary representatives of area levee and drainage districts, Mike Reed, superintendent of the Sny Island Drainage District, remains cautious. He knows from experience that flooding on the Mississippi River can materialize suddenly, with little warning, if rain begins to fall intensively.

"Getting into March and April, we start watching things pretty close," Reed said.

"Next week can look a whole lot different than it does right now. So you just have to be ready."

Reed said high river conditions have seemingly become the norm in recent years. Since 2001, when the river at Hannibal, Mo., crested at 26.91 feet, "we've had three of the top five crests in the history of the Hannibal gauge," Reed said.

In June 2008, the river reached its second-highest level of all time, 29.54 feet, and in April 2013, the river reached its fourth-highest level at 27.63 feet.

The record flood level at Hannibal was set in 1993 at 31.8 feet. The third-highest flood crest on record occurred in 1973 at 28.59 feet.

"The frequency of these events is definitely a concern," Reed said.

"It seems like since 2008, it's been every year we've had floods of moderate stages to pretty high. The only good thing is maybe we're going to be due for something that's ‘normal.' The only problem is, I don't know what ‘normal' is anymore," Reed said. "Normal used to be a whole lot different than what normal has been the last five years."

Reed acknowledged that while it's helpful to hear long-range flood forecasts that take into account past and expected rainfall and existing snow and ice levels in the upper Midwest, he's usually more concerned about rainfall that takes place in Northeast Missouri and Southeast Iowa.

"Sure, if there's rain in the upper Midwest -- up around Minnesota and Wisconsin and Northern Illinois -- that's going to come down the Mississippi and can create issues," he said.

"But in the last few years, the flood events that we've had here -- starting in 2008 -- have pretty much been dictated by Northeast Missouri and Southeast Iowa in terms of heavy rainfall. It comes down the Des Moines River, especially, but even the tributaries that flow out of East-Central Iowa and on into the Mississippi have really created problems."

Those problems, he said, can materialize quickly.

"Within a day or two we can have some serious issues," he said.

"If the river gets moderately high -- 18 or 19 or 20 feet on the Hannibal gauge -- we're concerned, and we watch that. But when we get to that stage, then we're really aware of what the weather is forecast and what occurs in Northeast Missouri and Southeast Iowa, because it can change overnight as far as what we have to deal with."

Reed said the Sny is in "really good shape" right now. Many improvements have been made within the district since the 1993 flood, and more improvements came after 2008.

Reed said some new roads have been built to provide better access to potential trouble spots, and more drain tiles have been added.

"We've also fattened our levees, so we've got much more material to work with," Reed said.