Mississippi receding after a Top 3 crest

After cresting along Iowa’s eastern border this week, the Mississippi River is now receding.

In the first week of April, historic snowpacks in Minnesota and Wisconsin melted in about 96 hours, with 6 to 10 inches of snowmelt rushing into waterways that fed into the river, according to senior service hydrologist Matt Wilson of the National Weather Service’s Quad Cities bureau.

“The vast majority of the floodwater came from that snowmelt … so that’s really unique,” Wilson said. “When we do our modeling forecasting, we go back to past events and look at that. There wasn’t a past event to go back to look at this current setup.”

The amount of snowpack, plus above average temperatures, created “worst-case scenario” conditions, he said. Thankfully, not much rain fell to add to the swollen waterways.

“This could very easily have turned the new flood of record,” Wilson said. “I would say we definitely dodged the bullet there with not getting very much rainfall.”

Iowa river communities from the Minnesota border to Muscatine were hit hardest by the flooding.

The Mississippi crested in northeast Iowa around April 28. Water levels at Lansing in far northeast Iowa hit 19.61 feet — the fourth highest crest on record and just below major flood stage.

McGregor surpassed its major flood stage, reaching 22.91 feet on April 28 — the city’s third highest crest on record. Most of the homes on Bergman Island, a residential community in the Mississippi River across from McGregor, flooded.

Crests peaked in the top three historical records for several communities further south, too, including Guttenberg, Dubuque and Bellevue.

“From Le Claire north, it's all top five flood events,” Wilson said. Le Claire is just north of Davenport.

Downstream, crests were less severe.

Davenport saw its seventh highest crest on record at around 21 feet; Muscatine saw its eighth highest at around 22 feet; and Burlington saw its 15th highest at around 20 feet.

Infrastructure

Flood infrastructure held up well on both sides of the river, Wilson said.

There was a report of a minor breach in Camanche in Clinton County, but it was quickly sandbagged and pumped.

The Iowa Department of Natural Resource’s Green Island Wildlife Management Area in Jackson County saw a levee break as well, but it was small and didn’t impact any homes or infrastructure.

“Everybody's flood infrastructure really got put to the test, and I think pretty much everything passed this year,” Wilson said.

Dropping levels

The rate at which the Mississippi’s water levels drop will depend on how much rainfall the region gets over the next few weeks.

Northeastern Iowa may see 1.5 inches of rain over the weekend. With the drier conditions over the past few weeks, soil should be able to absorb most of the rainfall.

Lansing already has exited flood stage. Bellevue should be out of its flood stage as soon as May 10.

Communities downstream should follow suit, with the Quad Cities moving out of flood stage around May 20.

Outlook

Looking ahead, Wilson doesn’t expect a return of last year’s record-breaking drought.

Seasonal outlooks project that Iowa as a whole should see average rainfall. Northern Iowa should have normal precipitation, and southern Iowa may see above average precipitation.

“I think it'll be good for farmers with negligible impacts on the rivers,” Wilson said. “It would take a few months of below average rain before we even come close to having to worry about barge traffic not making it up the river.”

Brittney J. Miller is the Energy & Environment Reporter for The Gazette and a corps member with Report for America, a national service program that places journalists in local newsrooms to report on under-covered issues.

Comments: (319) 398-8370; brittney.miller@thegazette.com