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Top 4 Worst Flooding Rivers in the U.S.

June 1, 2021

River flooding may be a natural environmental phenomenon, but for the millions of people whose homes are at risk of water damage, flooding rivers are a major concern. The number of home floods has doubled in recent years, putting homeowners at risk of financial loss or displacement. 

By analyzing several risks including flood duration, flood damage, and areas of impact, we've determined what are the top four worst flooding rivers in the U.S. Find out which waterways have caused the most problems. 

1. Mississippi River

The Mississippi River is one of the biggest rivers in the country. But for building and foundation experts, its most defining characteristic is how often it floods and the extreme duration of the flooding. 

According to the National Oceanic and Atmospheric Administration (NOAA), the Mississippi River at Baton Rouge has reached major flood stage 19 times in the last 50 years. That's nearly every other year that residents are dealing with a major flood. 

Flood durations are also significant. One of the worst flood events occurred just a few years ago. The National Weather Service reports that in northern Louisiana, the Mississippi River was above flood stage for a total of 226 days in a row, entering flood stage in 2018 and ending in 2019. During that time, the most severe flooding happened after the spring thaw of 2019, which coincided with heavy rainstorms. The event was named one of NOAA's billion-dollar weather disasters, and flood damages totaled $6.4 billion.

The sheer volume of water combined with the shape of the terrain creates a high flood risk. According to the USGS, the average water discharge at the river mouth is 593,000 cubic feet per second. That's more than 383 billion gallons of water each day. This constant onslaught of large volumes of water can overtake cities, communities, and homes. For comparison, the Colorado River is one of the principal waterways in the western part of the country, but it has just four percent of the water flowing through it as the Mississippi.

2. Missouri River

The Missouri River is second on our list because of the amount of damage the river causes when it floods. 

The 2019 Missouri Flood is a recent example of the type of extreme damage that can occur with damages topping $11 billion. That's about the same financial impact as when Hurricane Matthew made landfall on the coastal states in 2016. Between Omaha and Kansas City, every levee on the Missouri River was breached or overtopped. In St. Joseph, MO, north of Kansas City, the river crested at about 32 feet. That's 15 feet above flood stage. 

NASA satellite imagery for the St. Louis area where the Missouri River meets the Mississippi shows just how much impact river flooding had. 

worst river flooding in St. Louis, Missouri

The 2019 flood was not an isolated incident. The Missouri River has also had major floods in 1993 and 2017 in addition to ongoing flooding. 

3. Roanoke River

Although the damage caused by the Roanoke River may not be as widespread as other waterways, several factors add to its flood risk. Southwest Virginia has a mountainous terrain, and the elevation changes give the river added force. The bowl shape of the Roanoke Valley means that flash flooding can happen quickly. During the 1985 flood, residents had just minutes before their homes were completely surrounded by water. There has also been significant land development over the years, affecting the watershed and drainage.

According to measurements taken in Roanoke, the river has reached major flood stage six times in the past 50 years. Even while flood management practices are implemented, the problem persists. In the past 15 months, the river has been above flood stage five times. 

The 1985 flood caused about $440 million in damages to the Roanoke-Salem area, and after the May 2020 flood when the river crested at six feet above flood stage, there were reports of basements with three to four inches of floodwater.

4. Ohio River

Some of the worst river flooding in the country has been along the Ohio River. With about 182 billion gallons of water flowing through the river mouth each day, there is a significant amount of water flow, creating a high risk for flooding. 

The flooding along the Ohio River has caused some of the most memorable disasters. During the devastating flood in 1937, the Ohio River crested in Cincinnati at 80 feet. That's 15 feet above flood stage, and about one-fifth of the city was covered in water. Flood damage affected areas along the river from Pennsylvania to Illinois, and about one million people were stranded without livable homes.

In total, the Ohio River at Cincinnati has surpassed 60 feet 23 times since the National Weather Service began keeping records, and the most recent event occurred in 2018. However, the most severe flooding happened in earlier decades. Billions of dollars have been invested along the length of the Ohio River to mitigate flood damage. This has included floodwalls, levees, dams, flood control lakes, and sluice gates.

Even though the Ohio River still creates a flood risk, investing in better water management has already helped to minimize the severity of flood damage. In Cincinnati alone, the Army Corps of Engineers estimates that water management has helped property owners avoid $540 million in flood damage. 

How Can You Protect Your Home From Flood Damage?

A recent Groundworks survey found that only 13 percent of homeowners feel very prepared for a flood or major disaster. However, preparing for a flood may be easier than you realize. 

In our checklist for how to prevent flood damage, we break down key steps for how you can avoid flooding in the first place and reduce the amount of damage if flooding does occur. 

Protecting your home starts with effective water management. Drainage systems can keep water flowing away from your home, and automatic sump pumps can help you quickly remove water from your basement or crawl space. 

Even homeowners living outside of flood zones could be at risk because FEMA flood maps are frequently out of date. Scientific American reports, "More than one-third of the claims payments last year were for properties located outside areas that FEMA considers at the highest risk of flooding." 

Sign up for a free inspection from your local waterproofing and foundation repair experts to find out the best way to waterproof your home and help protect against flood damage.