Mississippi River floodwaters falling fast, but it could be weeks before a return to normal

The upper Mississippi River continues to experience its worst flooding in decades, but the waters were receding faster than expected as of Monday along the Wisconsin and Minnesota border.

Because of the sheer size of the river, even with that good news, it could be a while before the river returns to its banks.

The region is currently inundated by floodwaters due to excess snowmelt draining from the river basin.

Three sites — La Crosse, and McGregor and Guttenberg, Iowa — saw their third-highest floodwater peak on record, according to the National Weather Service.

Some flooding along the Mississippi happens every year, but this year, there was an unusually heavy and wet snowpack to the north. A string of 70-degree days in mid-April started melting the snow, and the water began pouring into tributaries on its way to the big river.

By Monday, the river's uppermost reaches had already crested and were falling relatively quickly, said Jordan Wendt, service hydrologist for the National Weather Service's La Crosse office. For example, floodwaters in Minnesota's Lake City — about 70 miles downriver from the Twin Cities — had already fallen three feet since their crest last week, Wendt said.

That may be because downstream rivers that feed into the Mississippi, like the Missouri and the Ohio, aren't flowing quite as high, which means the Mississippi can handle more water from upstream at those points. If there also was flooding downriver, it would cause a "traffic jam" that would make upriver water levels recede at a slower pace, he said.

More: As heavy, wet snow melts, upper Mississippi River floods to near record levels

The river has crested down to the Illinois and Iowa border and is expected to peak in the Davenport, Iowa, and Rock Island, Ill., on Tuesday, Wendt said.

Because "fast" is a relative term for a giant river like the Mississippi, it will still be several days before the river itself falls back below flood stage, Wendt said. That's expected around May 10 for sites along Wisconsin. Then it could be at least another week until it returns to its banks.

As the floodwaters recede, people should be careful about being close to the riverbank because of the debris that will be left behind, Wendt said.

Meanwhile, barge transportation along the upper river is still paused because of the closure of locks and dams. Patrick Moes, deputy public affairs chief for the U.S. Army Corps of Engineers' St. Paul District, said all the locks and dams in the district may open again by Thursday. But that will depend on how fast the waters recede and, in some places where water levels overtopped lock structures, whether any repair of the structures are needed. Army Corps staff will do inspections as soon as they're able, Moes said. As of Monday, nine locks and dams were closed further down the river in the Corps' Rock Island District.

Spring shipping season is a key time for fertilizer to be shipped upriver, destined for Midwest farm fields, said Dennis Todey, director of the U.S. Department of Agriculture's Midwest Climate Hub in Ames, Iowa. If barges can't move upriver to deliver that fertilizer, it could cause problems for the growing season.

More: Five things to know why this spring's Mississippi River flooding is particularly bad

The flooding shouldn't cause much direct damage to agriculture, Todey said, because not many farming acres directly abut the river, and some of those that do are protected by levees.

There's no indication in the upcoming forecast that river flooding could get worse, Wendt said. Cooler-than-normal air over the region this week should keep the chances of precipitation low. Next week, however, warmer air could create thunderstorms and prolong the floodwater recession slightly.

The flooding is a reminder that climate change will mean the region could see more extreme and unpredictable weather in the years ahead. Wisconsin's climate is expected to grow warmer and wetter over the century, according to the Wisconsin Initiative on Climate Change Impacts. That contributes to rainfall intensity, with more rain falling in a shorter period of time in more concentrated areas.

Wendt pointed to the last several months as an example.

"We had a significant drought last fall, and then just six months later, we completely reversed that and experienced a top-three flood on record for some locations," he said.

Madeline Heim is a Report for America corps reporter who writes about environmental issues in the Mississippi River watershed and across Wisconsin. Contact her at 920-996-7266 or mheim@gannett.com.

This article originally appeared on Milwaukee Journal Sentinel: Mississippi River floods have peaked along Wisconsin, Minnesota border