The historic flooding of the Missouri River in 2019
Meetings are being held by the US Army Corps of Engineers from the Kansas City and Omaha Districts across the area to help analyze and recommend flood improvements for flood risk management and other water resource-related issues along the Lower Missouri River. These series of meetings were prompted by the historic and devastating flooding of 2019, an event that resulted in record runoff and billions of dollars in damage across the region. More specifically, billions of dollars in damage was done to communities in Iowa, Nebraska, Kansas, and Missouri. Repair costs to the levee infrastructure in the lower river were approximately $1.2 billion.
The reason behind this flooding was due to the extremely wet and snowy September and October of 2018. This left the soil saturated as the ground froze along the river. Then, in March, a bomb cyclone, which is a rapidly intensifying low-pressure system, dumped 3 feet of snow on the ground in several areas before temperatures then climbed into the 60s over the following days. By only a week or two after that event, on March 11th, 2019, almost all the snow had melted, and the runoff had nowhere else to go.
The rapid melt, combined with several more inches of rain across the Midwest, sent water rushing over frozen ground that couldn't absorb any of the water. All of this water then poured into local streams and rivers, and eventually, the Spencer Dam in Nebraska couldn't handle it. The dam broke, sending a significant wall of water downstream into the mouth of the Missouri River. Not only was this an issue, but some of the rivers this water moved through were still frozen. This led to massive ice jams that further elevated the water as it moved downstream. This caused widespread devastation, and the influx of water continued into Missouri. This broke levees and caused floods all the way into St. Louis. Even after this event, continuous rainfall during this active year resulted in little relief from elevated water levels, as record rainfall was observed in the Missouri River Basin during the spring and summer seasons. Some of the dams along the Missouri River during this time were releasing water at over double the typical rate for that time of the year, which is another reason why it took so long to actually observe relief.
As for the outlook this year, the US Army Corps of Engineers reported that the runoff in the Missouri River Basin above Sioux City was 1.0 million acre-feet, which is around 130% above average. This is because of the above-average temperatures that have been persistent across much of the country, leading to early snow melt. Due to the now below-average plains and mountain snow pack, the forecast for 2026 is set to be a below-average runoff year for the Basin, and more specifically, the upper Basin. This means that there will be reduced flow from reservoirs, and that it is much less likely that the type of flooding observed in 2019 will occur this year.
