Before the closure of Fort Randall Dam in 1952, the Missouri flooded two times a year. The first flood occurred in late March and early April. Old timers called this flood the April fresh (for freshet), the April rise, or the spring rise. The melting of the plains and prairie snowpack caused the April rise. The size and duration of the April rise depended on the depth of the snowpack, the moisture content of the snow, and how quickly the snow melted and ran off into the Missouri and its tributaries. Predictably, the worst spring rises occurred at the end of long, snowy winters. The April rise always began with ice-out – the moment when the Missouri shattered its icy surface.
Once freed from winter’s embrace, the Missouri sent massive ice chunks downstream, where they bunched up at the head of islands or inside hairpin bends. Occasionally, the accumulated icebergs formed an ice jam. Some ice jams became so large and so tightly woven that they reduced the downstream flow of the river to a trickle. On the upstream side of the biggest ice jams, the Missouri backed up and overtopped its banks, inundating the nearby valley lowlands. Eventually, intense water pressure built-up against an ice jam and blew it out, sending a wall of water downstream, which caused further flooding. These first floods of the year remained localized and lasted only a short while. A far larger flood descended the river immediately on the heels of ice-out.
The first week of April brought longer daylight hours and warmer temperatures, melting the river’s ice flows. Just as the threat of ice jams came to an end, more snowmelt poured into the river. As the Missouri became engorged with runoff, fast-moving floodwaters swept across segments of the valley floor, lifting up logs, brush, animals, fence posts, and farm houses. The deepest, fastest section of the river, known by the German word “thalweg,” filled with flotsam. The thalweg was discernible by the streak of foam and debris snaking its way downstream. If anyone wanted to know the land and the people living on it, the thalweg revealed the secrets of both in the artifacts it carried in its thrashing waters.
Most April rises came and went in a matter of weeks. The river’s greatest spring rise took place in 1881. During the winter of 1880-1881, successive blizzards dumped up to four feet of snow on portions of Dakota Territory. Then, in March, warm Chinook winds streamed northward from the southern plains into Montana and northern Dakota Territory. The supercharged air quickly melted the deep snowpack. Within days, huge quantities of water poured off the plains and into the still-frozen Missouri. When the meltwater hit the ice-covered Missouri, it quickly pushed the river out from under its icy covering.
Let loose, the Mighty Mo rumbled downstream in a terrifying mass of icebergs, downed trees, and dead cattle. This slushy junk pile slammed into one valley town after another. Dakota Territory bore the brunt of the Missouri’s fury. The Missouri pounded Greenville, Yankton, Gayville, Meckling, Burbank, and Elk Point. The worst devastation struck the fledging frontier town of Vermillion, which was nearly wiped off the map. Vermillion’s business and residential districts lost 132 buildings to ice flows and high water. Later in 1881, Vermillion’s residents wisely chose to give the river room to roam; they moved the town and its few surviving buildings from the valley floor to the top of the bluffs.
Following the passage of the April fresh, the Missouri fell back behind its high banks. In the 19th and early 20th centuries, the river could drop quite low in May. Prince Maximilian of Wied, who went up the Missouri on the steamboat “Yellow Stone” in 1833, noticed the river at low stage during that month. Since the “Yellow Stone” got hung up so often on the river’s sandbars, the prince was able to spend countless hours on shore pursuing one of his hobbies – the observation and recording of flora and fauna.
In May 1869, Emma Dickinson travelled up the Missouri on the steamboat “Mollie Ebert.” As a female traveler, Dickinson did not have the social license to disembark from the steamer and explore the valley and its creatures whenever the steamer got stuck on a sandbar. As a result, she found herself confined to the boat whenever it skidded to a stop on a sandbar. On May 7, 1869, she wrote with obvious frustration, “We did not travel far before we struck a sand bar and was seven hours working to get off it.” That same evening she again expressed her exasperation with the low water level of the Missouri, “Six O’clock and stuck again.” Years earlier, Joseph Nicollet went up the Missouri on the steamboat “Antelope.” He too noted the river’s low stage in May. Near today’s Ponca, Nebraska, Nicollet’s boat remained firmly embedded in a sandbar for nine days.
In June, the river experienced its second annual flood. This flood was known as the June rise or summer rise; it lasted longer, carried more water, and covered a larger area than the smaller, shorter April rise. In June, the Missouri became something altogether different – something to behold. The summer rise resulted from the melting of the Rocky Mountain snowpack and the commencement of thunderstorms in the middle and lower Missouri Valley. When the snowmelt cascading off the mountains joined with the rain water flowing into the Missouri from the plains and prairies, the Missouri grew to a truly impressive size. While stationed in today’s North Dakota in the early 1860s, Henry Boller witnessed the start of the June rise, “The Missouri commenced to feel the melting of the snows in its mountain tributaries and its swollen and turbid waters rushed and foamed wildly.”
In the reach through today’s western Iowa, the river possessed an average width of between 5,000 and 10,000 feet. However, during the June rise, the Missouri expanded to five, ten, even fifteen miles in width. European-American settlers noted how the river in June sometimes stretched all the way from the Loess Hills of Iowa to the bluffs in Nebraska. During the June rise of 1851 (which actually began in May of that year), Charles Larpenteur observed that the entire fifty-five miles of valley bottomland between Sergeant’s Bluff (at today’s Sioux City) and his farm at the mouth of the Little Sioux River lay under the river’s high waters. Henry Brackenridge saw a similar scene during the June rise of 1811. He wrote, “It was with difficulty that we could obtain dry land this evening, the water, in most places, flows into the woods – in the night, the water has risen so much….”
In 1903, one of the biggest June rises in European-American history came barreling down the valley. In early May of that year, heavy rains fell upon Iowa, Nebraska, Missouri and Kansas. Between May 16th and May 31st, it rained every day in portions of north-central and northeast Kansas. The saturated land could not absorb the additional rainwater, so the water hurriedly poured into the Kaw and Missouri rivers. By May 31, the Kaw had risen far beyond its banks. At Lecompton it carried 320,000 cubic feet per second (cfs). When the flooding Kaw crashed into the already swollen Missouri, the two rivers drove one another even higher. At the peak of the flood on June 2, the Missouri hauled 548,000 cubic feet per second (cfs) past Kansas City. That crest equalled nearly ten times the river’s average discharge rate of 56,950 cfs at that location. The surging river pushed into the industrial and railroad districts of the two Kansas Cities. The neighborhoods of West and East Bottoms sank beneath as much as twelve feet of fetid water. Before the flood came to an end, the Missouri inflicted wide-scale destruction on buildings, rail lines, bridges, and residential areas. Large June rises came down the Missouri in subsequent years, but few of those later floods matched the size and destructive force of the 1903 deluge.
In some years, the June rise lasted into July or August; but by September the river fell back within its banks. In October and November, the Missouri experienced another rise – the result of fall rains across the plains and prairies. Then, with the onset of winter, the river dropped to its lowest levels of the year. The Missouri remained low until March, when the flood cycle began again.