Rain - and lots of it - was forecast for Arnold, Missouri, a town of 21,000 at the confluence of the Meramec and Mississippi rivers, 20 miles south of St. Louis.

The remnants of Tropical Storm Gordon were on their way, and the National Weather Service had issued flood warnings. By September 12, the Weather Service said, the Meramec could crest at 28.1 ft, more than 4 ft above flood stage.

“We get hit from two directions,” said Mayor Ron Counts several days before the storm was due to arrive, threatening the annual Arnold Days celebration on the river. “We’re surrounded by water,” said the 71-year-old mayor, who grew up in Arnold and owned a business there.

Mississippi River flood at Cape Girardeau, Missouri, in 1993.This year marks the 25th anniversary of a prolonged flood that hit the region from April to October 1993, and caused an estimated $15 billion in damage. More than 1,000 levees either failed or were overtopped across a swath of the Mississippi River basin. That flood was considered by many the equal of a 1927 flood that prompted President Calvin Coolidge and Congress to direct the U.S. Army Corps of Engineers to build levees and other flood control structures to tame the Mississippi.

But Mayor Counts says that a 2015 flood may have been worse still. Water covered Interstate 55, which connects St. Louis with cities and towns along the lower Mississippi.

“I’ve lived here all my life, and in my opinion the flooding has gotten worse.”

His opinion is shared by others. A December 2016 research paper published in Hydrological Processes concluded that flooding is becoming more common, and economic losses are rising, including states along the main stem of the Mississippi River.

What’s more, the Mississippi River Cities and Towns Initiative (MRCTI) says that since 2005, the Mississippi River valley has endured successive 100-, 200- and 500-year floods, a 50-year drought and hurricanes Katrina and Isaac. Disasters along the Mississippi River have become “persistent and systemic,” MRCTI says. In the last decade, 30 states have issued 10 or more disaster declarations; six states have issued 20 or more.

Arnold, Missouri, Mayor Ron Counts.Cities and towns are rethinking their relationship with their river, and in some cases, their reliance on levees and other gray infrastructure to protect them. Interest is growing in restoring wetlands and other natural resources to help mitigate flood risk and boost resiliency.

A River Flows Through It

The Mississippi River rises in northern Minnesota and flows 2,320 miles south to Louisiana, where its multi-fingered delta empties into the Gulf of Mexico. Including tributaries such as the Ohio, Missouri and Arkansas rivers, the Mississippi River basin drains around 40% of the continental U.S. That makes it one of the five largest river basins in the world.

The 1993 flood persisted through much of the summer. Source: NOAAThe river has been an economic engine for centuries, at least back to the days of French trappers and explorers intent upon exploiting the region's natural riches. According to the Mississippi River Commission, founded in 1879, more than 100 electric power plants now lie along or near the river, along with 12 major oil refineries, and commercial and agricultural enterprises that generate on the order of $500 billion a year. Major cities and towns include Minneapolis, St. Louis, Memphis and New Orleans, as well as fictional character Huck Finn’s hometown of Hannibal, Missouri.

The 2016 journal article by hydrologist Robert Criss of Washington University in St. Louis and Mingming Luo of the China University of Geosciences argued that levees and other control elements along the river’s length play a role in increased flooding. They say that as far back as the mid-1850s warnings were voiced that levee construction would aggravate flooding in the Mississippi River valley.

Rainfall in December 2015 covered the entire Meramec River drainage. Source: Washington University/National Weather ServiceStudies published between 1975 and 2008 seem to confirm that early suspicion, Criss and Luo said. Urban sprawl and development in floodplains have increased the amount of property and infrastructure at risk of floods. And evidence suggests to some that heavier and more frequent storms are dumping more water onto the watershed.

Rain Events

Scientists think that one impact of a warmer climate may be more frequent and intense rain events in the Upper Midwest, including parts of the Mississippi River basin. For example, more than 31 in of rain fell on Ames, Iowa, between May and August 2018, nearly equal to the total precipitation for all of 2017. In Des Moines, Iowa, officials are spending $110 million over 10 years to raise three vehicle bridges, install pump stations, raise levees and better protect the city’s wastewater treatment facility from floods.

Tonya Graham, Geos Institute“The ’93 flood reminded people of how big floods can be,” said Tonya Graham, executive director of the Oregon-based Geos Institute, whose aim is to help communities build resiliency in the face of a changing climate. Flooding along the Mississippi in particular is “much more chronic” in recent years, she said, noting that the river rises faster and offers less time to prepare than in the past.

Graham and colleagues are working with towns like Arnold through St. Louis-based MRCTI. The organization was founded in 2012 and includes 86 cities and towns from the 11 states through which the river’s main stem passes.

In March, MRCTI released a nearly $8 billion proposal to restore the river’s floodplains and ecosystems and modernize its lock-system.

“We want to naturally create slack rather than wall the river and send the risk downstream” to other communities, says Colin Wellenkamp, its executive director. The idea, he says, is to “give the river room to move around.”

Colin Wellenkamp, MRCTIGray infrastructure such as walls and levees constrain the river and accelerate its velocity as floodwaters flow south. That accelerated rate of flow can batter bridges and helped lead to the decision to raise a bridge over the Meramec River in Arnold.

“In addition to hard engineering, people are looking at what else can be done,” Graham says, including “asking where a river might access its natural floodplain.”

Stepping Back

That approach is leading some cities to move structures back from the river’s edge and to look to green spaces to offer play space for residents as well as a buffer from floodwaters. Wellenkamp says that after the 1993 flood, officials in Grafton, Illinois, around 60 miles upriver from Arnold, decided to pull the town back by removing at-risk structures. They also restored wetlands on Grafton’s upstream side to absorb flood waters before they could reach the town.

By contrast, the town of St. Genevieve, Missouri, around 45 miles downriver from Arnold, elected to spend more than $50 million to strengthen a levee. That investment offers the town additional security, Wellenkamp says, but the infrastructure also shifts flood risk downstream.

Officials in Des Moines, Iowa, spent $3 million to raise this bridge 54 inches. One of those downstream towns is Cape Girardeau, 60 miles farther south. During the 1993 flood, more than 150 homes in the floodplain were damaged. Plans to buy out homeowners were shelved due to cost concerns. But the river flooded again in 1995 and reached 46.7 ft, just short of the 1993 crest of 48.5 ft. This time 100 homes flooded, including some that had only just been repaired from the earlier flood.

The flood prompted the city to buy 114 properties in flood-prone areas at an average cost of $23,600 per home. The expense was shared among federal, state and local sources, as well as non-profit organizations. The land then was deed-restricted for open space.

The 1927 flood prompted widespread construction of levees to control the Mississippi. Source: NOAA photo libraryA floodwall dating from 1964 also was updated. And four years ago, the city spent $72 million to relocate its wastewater treatment plant. A year later, it moved its trash transfer station away from the river at a cost of $3.9 million.

Officials didn’t have to wait long to see their investments tested. In 2015 the same floods that closed I-55 in Arnold also hit Cape Girardeau. With improvements in place, the Federal Emergency Management Agency says the city withstood the flood with minimal damage.

Paying for Disaster Preparation

MRCTI claimed victory earlier this year when Congress voted to increase funding for disaster preparation from $22 million to $246 million. Wellenkamp says that money will help cities and town prepare for the impact of floods, droughts, excessive heat and fires, a relatively new and growing risk. The federal money, however, is a fraction of the billions of dollars Wellenkamp says are needed to better address risk along the Mississippi River. He calculates that every $1 in mitigation investment saves $6 in disaster response.

MRCTI seems like an unlikely coalition that embraces big cities and small hamlets alike, not to mention political divisions that prove poisonous in other parts of the country. But Wellenkamp says that officials up and down the Mississippi realize that a more unified approach to disaster mitigation and resiliency reflects the river’s complex interconnected nature. And it isn’t just engineering and gray infrastructure that needs to be addressed: social costs and economic development figure into discussions about life along the Mississippi River.

As part of its work, MRCTI hopes to identify where communities’ most vulnerable people are and how flood mitigation investments may impact them.

“We are finding that communities that are economically challenged are already struggling with climate events,” Graham said. “How can we best invest in infrastructure to help communities that are vulnerable and struggling?”

Meanwhile, as the rag-tag remnants of Tropical Storm Gordon neared, Arnold’s Mayor Ron Coats was watching the weather forecast. If rain once again sent the Meramec River above flood stage, the town park could be forced to close. And that, the mayor worried, just might wash out this year’s Arnold Days celebration altogether.