The Big Sioux: A Brief Environmental History

A view of the Big Sioux River north of Sioux City, Iowa, circa 1900. The excursion boat “Minnehaha” in the foreground. Photograph courtesy of the Sioux City Public Museum.

On Saturday, May 13, 1843, the steamboat Omega glided along the eastern edge of the Missouri River near today’s Sioux City, Iowa. As the sun set behind the bluffs to the west, the boat’s passengers and crew gazed apprehensively from the ship’s decks at an approaching thunderstorm.

On the wide Missouri a thunderstorm accompanied by high winds could pummel a steamboat, tossing it against snags, slamming it up against a cut bank, or pushing it atop a sandbar. Fearing for his vessel and its passengers, the Omega’s pilot guided the steamer into the mouth of the Big Sioux River. Once there, the boat’s roustabouts hurriedly roped the ship to the shore. Not long afterwards, the thunderstorm broke over the Omega, but thanks to the actions of the pilot and crew members, and the sanctuary offered by the Big Sioux, the storm did not damage the ship.

A famous passenger on board the Omega provided posterity with one of the few early descriptions of the Big Sioux River. Ornithologist John James Audubon wrote, “…[we] have entered the mouth of the Big Sioux River, where we are fastened for the night. This is a clear stream and abounds in fish….”[1] Audubon then listed a few of the animals found in the vicinity of the river, including geese, deer, and elk.

Although Audubon’s description of the Big Sioux is brief, its words are surprising. Specifically, Audubon referred to the river as “a clear stream.” For those familiar with the modern Big Sioux, it is hard, if not impossible, to imagine the river as a “clear stream.” The reason is that today’s Big Sioux at its confluence with the Missouri is a dark brown – its waters brimming with mud, e coli, and fecal coliform.

The lower reaches of the river are so filthy that scientists have warned people not to swim in the stream or even dip a hand into its waters, especially if that hand has any kind of open wound. Those same scientists caution that a day spent canoeing or kayaking on the river could be hazardous to your health.[2]

In 2012, following an extensive examination of data from the Environmental Protection Agency, the environmental watchdog Environment America listed the Big Sioux as one of the top twenty most polluted rivers in the United States – and the U.S. possesses about 250,000 rivers and streams.[3]

The contemporary Big Sioux isn’t just polluted, it is also hydrologically unstable. The river now floods regularly, sometimes two, three, or four times a year. Climate change, along with the intensification of agriculture across the river’s drainage basin, are the biggest drivers behind the river’s present volatility. Both have led to increased runoff, which in addition to fostering floods, has altered the stream’s morphology. Along certain river reaches, the meandering, wood-lined channel of old is giving way to a treeless, braided channel area.

Like the river’s water quality, its flow regime, and its channel morphology, the make up of the river’s fish population is dramatically different today than when Audubon encountered the Big Sioux. Aided by flood flows and changes in turbidity, invasive species, such as the German carp and the Asian carp, have in recent years muscled out native fish. The Asian carp entered the Big Sioux about fifteen years ago. It is so aggressive, reproduces so successfully, and grows at such a rapid rate that scientists fear it may, in the next few years, inhabit the entire length of the river; if it does, it may push the last remnant populations of native fish to the brink of extinction.[4]

What follows is a brief overview of how the Big Sioux went from a clear, biologically-diverse, prairie river to one of the most hydrologically-erratic, polluted, and ecologically-compromised rivers in the United States.

River and Basin

The Big Sioux River heads in the Coteau des Prairies region of northeast South Dakota near the town of Summit. From there it meanders 419 miles to the south, joining the Missouri at Sioux City, Iowa.

The river’s drainage basin encompasses 8,430 square miles, which is nearly the same size as the state of New Jersey. From the basin’s northernmost tip to its southern endpoint, the Big Sioux falls about 1,000 feet, or a little over two feet per mile. This slight drop in elevation explains why the stream has such a sluggish current, measured in its middle reaches at a mere two miles per hour.

In the nineteenth century, and throughout most of the twentieth century, high flows usually descended the river in April and again in June. This hydraulic regime mimicked that of the Missouri.

The April pulse followed the break-up of the river’s ice and the melting of the prairie snowpack. The height and duration of this pulse depended on the depth of the snowpack, how fast it melted, and whether it was accompanied by rainfall or snowfall. Not surprisingly, the greatest spring pulses occurred at the tail end of cold, snowy winters, when temperatures suddenly spiked, causing the prairie snowpack to melt in a hurry. Such a pulse occurred in April 1881.

On April 17, 1881, the river’s ice broke up. Three days later, the river overtopped its banks along much of its length. The fledging community of Sioux Falls took a battering from the Big Sioux. Thick chunks of ice and fast-moving water smashed or carried away thirty-three of the town’s buildings, including Weber’s Restaurant, Olson’s Blacksmith Shop, and Cochran’s Stable.[5] Ida Avery, an early settler along the river near Medary, Dakota Territory, remembered that in spring 1881, “There was water everywhere.”[6]

The most damaging spring pulse in modern times occurred in 1969; it followed the long-established pattern, arriving on the heels of a harsh winter. The 1969 deluge sank North Sioux City, South Dakota, and most of Riverside (a neighborhood in the Sioux City metroplex).

On average, the spring pulse passed downstream in a week or two.

The June pulse resulted from spring and summer rains. Unlike the April pulse, it took time to build. Successive rains gradually raised the river over the course of several weeks. However, sometimes, a single, massive rain event rapidly raised the river. The Army Corps of Engineers, which conducted a study of the Big Sioux in the late 1920s, acknowledged that in the decades after agricultural settlement, “…high flows are apt to occur at almost any time, due to the erratic incidence of heavy rainstorms. High water flows are flashy….”[7]

The drainage basin’s narrow profile also contributed to “flashy” high flows by quickly concentrating runoff in the river’s main stem. On June 20-21, 1954, a brief surge of water tore down the Big Sioux after several days of intense rainfall across the basin. Some areas within the watershed reported eleven inches of rain in the four days immediately prior to the inundation. This sharp, short freshet caused an estimated $1.2 million in damages (the equivalent of $11.6 million today).[8]

A unique hydrological event occasionally struck the lowest reach of the Big Sioux. It occurred when the Missouri rose so high that the Big Sioux backed up and inundated the lowlands near its mouth. This happened in April 1952 when the engorged Missouri forced the Big Sioux to reverse course and pour its waters into Riverside and North Sioux City.

The Prairie River

The pre-settlement Big Sioux ran clear from its head to its mouth. The reason for the river’s clarity had a lot to do with the vegetation growing across its drainage basin, especially the prairie grass known as big bluestem.

Big bluestem blanketed the entire Big Sioux watershed. It grew atop the uplands, down in the lowlands, and in every nook and cranny in between. The grass, along with its interconnected root system, acted as a vast, natural filter. Runoff, whether from snowmelt or a drenching thunderstorm, had to pass through a gauntlet of grass before reaching the Big Sioux. Consequently, when runoff finally arrived at the river’s edge, it was often clear, having left behind any gravel, sand, or mud that it may have picked up while traveling downslope.

In 1865, W.W. Brookings came upon the Big Sioux between Egan and Flandreau, Dakota Territory. He commented on the river’s untainted, sparkling water and hinted at the likely reason for it. “The Big Sioux River at this point is a clear running stream with rocky bottom. The bottomlands consist of rich alluvium, bearing a very heavy grass….”[9] Brookings’ “heavy grass” was likely big bluestem.

Seasonal and perennial wetlands also contributed to the pre-settlement river’s water quality. Like big bluestem, wetlands either slowed, or completely stopped, the movement of sediment toward the river.

But wetlands and grass did not just enhance water quality; both lessened the likelihood of floods. Wetlands acted as natural reservoirs, storing runoff that would otherwise have entered the river. The basin’s heavy mat of grass did the same; it absorbed runoff and prevented it from flowing into the river, where it could have caused a rapid rise in water levels.

Since runoff usually dribbled into the stream, excessively-high, destructive pulses of water rarely moved through the river’s main channel in the years prior to agricultural settlement. In consequence, the Big Sioux experienced very little bank erosion, which meant that along its entire length, the river’s banks gradually angled down toward the waterline.[10] Residents of Sioux City in the early twentieth century remembered that near its mouth the Big Sioux had gently-sloping, sandy beaches – perfect for sunbathing and swimming.[11]

Those who encountered the Big Sioux, either before or soon after the agricultural settlement of its basin, remembered not only the river’s clarity, its gravelly bed, and its gently-sloping banks, but also its depth. In 1844, U.S. Army Captain James Allen wrote of the Lower Big Sioux through Plymouth County, Iowa. “[The Big Sioux] here is a large stream, larger than the Des Moines below the Raccoon, not quite so broad, but is deeper, and runs more water.”[12] In the early twentieth century, the Army Corps of Engineers measured the river’s depth at its mouth at fifteen feet. And upstream at the confluence of the Rock and Big Sioux rivers, the latter stream still ran ten feet deep.[13]

The clear, pre-settlement waters of the Big Sioux held a variety of fish, including channel catfish, northern pike, smallmouth bass, largemouth bass, rock bass, perch, mooneye, goldeneye, freshwater drum, sauger, spoonbill, shovelnose sturgeon, and buffalo fish. These fish swam in the river’s main channel, its small oxbow lakes, and some of its tributaries. Many of these species are sight feeders – further proof of the Big Sioux’s former clarity.[14]

Changes in Land Use

Within fifteen years after the end of the Civil War, most of the land within the Big Sioux basin had been taken up by European-American colonists. Those colonists worked diligently over the next several decades to transform the tallgrass prairie into cropland.

Consider Sioux County, Iowa, which abuts the eastern side of the lower Big Sioux. In 1870, the county’s 492,160 acres (or 769 square miles) were almost entirely covered in big bluestem, wetlands, and small tracts of timber. By 1910, 159,817 acres (250 square miles) within the county had been planted in corn. Another 91,336 acres (143 square miles) had been planted in oats. Only 30,432 acres (47.5 square miles), or about six percent of the county’s entire land area, remained uncultivated. That uncultivated land likely consisted of a combination of seasonal and perennial wetlands, river bottomland, timber tracts, and native prairie.[15]

The radical environmental transformation of Sioux County between 1870 and 1910 was not unique. The same thing happened in every other county within the Big Sioux basin – the prairie fell to the plow.

The loss of the tallgrass prairie contributed to two interrelated problems along the Big Sioux River: siltation of the streambed and floods.

Excessive siltation of the Big Sioux’s streambed began soon after settlement and intensified in subsequent decades as farmers put more land into crops. The reason the Big Sioux’s streambed filled with silt is easy to explain. In the wake of a heavy rain, or following the melting of the winter snowpack, newly-cultivated land within the Big Sioux basin lacked the ground cover to halt, or even slow, the downslope movement of eroded soil. In consequence, topsoil from the uplands began pouring down into the river channel. Once there, the river’s slow current could not haul all the sediment away. As a result, mud piled up in the river channel, burying the stream’s former gravel bars, increasing the river’s turbidity, and raising the streambed. The new, elevated streambed reduced the river’s conveyance capacity, meaning its ability to carry high flows downstream without overtopping its banks.

Long-time residents of the Big Sioux Valley recognized that siltation of the streambed in the decades after European-American settlement had made the river more flood-prone.

Harry Colvin was born in 1882 in Sioux City, Iowa. In 1954, a reporter with the Sioux City Journal asked Colvin how the Big Sioux River had changed since he had been a boy. Colvin stated unequivocably that the river had become more flood-prone because of siltation of the streambed. He remarked, “Flooding wasn’t at all common in the old days…because the river could carry more water.”[16]

Alanson Baker was born in 1880. He spent his entire life on a farm near the Big Sioux at Akron, Iowa. In 1962, he told a reporter with the Sioux City Journal that since his childhood a huge amount of topsoil had drained down from the farmed uplands into the Big Sioux Valley. Baker estimated that millions of tons of eroded soil had been deposited in the valley and atop the river’s streambed. All of that eroded topsoil had worsened flooding along the stream.

An article on the Big Sioux published in the Sioux City Journal in 1954 summed up the thinking of those who had witnessed firsthand the changes in the Big Sioux since agricultural settlement. The article stated, “[Valley residents] assert that the Big Sioux isn’t as deep now as it once was in the 1870s and 1880s, also that floods were not as bad in the early years.”[17]

The observations of early valley residents were confirmed by a 1910 report completed by the Department of Agriculture. The report stated, “It is quite probable that the stream’s capacity for carrying floods is being diminished rather than increased.” The report went on to note that the river’s channel area was being reduced by the deposition of topsoil “…from newly cultivated territory.”[18]

The Floods Cometh

The siltation of the Big Sioux’s channel area, and the corresponding decrease in the stream’s conveyance capacity, produced predictable results. The river flooded more often and at greater heights.

In addition to the previously-mentioned flood of 1881, major floods inundated the valley in 1897, 1904, 1905, 1906, 1907, 1908, 1909, 1919, and 1920. Localized floods struck some portion of the valley in 1903, 1910, 1911, 1912, 1913, 1914, 1916, and 1917.[19]

A further contributing factor to the above floods was what was referred to in the early twentieth century as the “drainage craze.”

The craze involved the drainage of wetlands, the tiling of cropland, and the straightening of the Big Sioux’s tributaries to rapidly move rainwater and snowmelt off cropland. In 1910, the Department of Agriculture commented on how these additional changes in land use affected the Big Sioux’s flow regime. “Considerable areas in the Dakotas have been drained in the past six or eight years, and more work of this nature is contemplated. This drainage has the effect of more quickly concentrating the run-off in the main stream….”[20]  In other words, the drainage craze made the Big Sioux, already prone to flash floods because of the shape and topography of its basin, and already experiencing problems with siltation, even more flood-prone.

The floods after 1914 may have been made even worse by the war in Europe, which drove up commodity prices and encouraged Midwestern farmers to put still more land into crops. For instance, between 1910 and 1920, farmers in Lyon County, Iowa, (another Iowa county that abuts the Big Sioux’s eastern shore), increased the amount of land in wheat from 1,606 acres to 4,282 acres. In Sioux County, wheat acres jumped from 13,546 to 19,681 in the same period. While the amount of wheat acreage increased in the 1910s, the amount of forage crops decreased a corresponding amount. Forage crops, like native prairie grass, provided better runoff retention than row crops such as wheat.[21]

Farmers in the Big Sioux Valley did not remain silent while the river flooded year after year. They demanded that the Army Corps of Engineers, the federal agency with authority over the river, stop the floods or at least lessen the damages resulting from the river’s high waters. Farmers throughout the valley wanted the Corps to consider two flood control measures: levees and cut-offs. Levees would protect agricultural land from high flows, while cut-offs would straighten the river channel and hasten the movement of floodwaters downstream.

Following a survey of the river in 1909, the Corps ruled against any federal flood control projects along the Big Sioux. The cost of constructing levees and cut-offs exceeded the value of the agricultural land subject to flooding.[22]

Although stymied by the Corps, valley farmers did not give up on their dream of an “improved” Big Sioux River. In 1915, the U.S. congressional representative from Sioux City, George C. Scott, (no relation to the actor), asked the Corps to consider a series of cut-offs along the river north of that city. The Corps again rejected the idea, arguing that stream straightening would dump eroded topsoil along certain river reaches, worsening flooding on adjacent lands. Cut-offs would also increase the river’s current velocity, which would lead to severe bank erosion in some locales. Most worrisome to the Corps, channel straightening below Westfield, Iowa, would likely concentrate floodwaters at Sioux City.[23]

In 1919, after another lobbying effort by valley residents, the Corps again nixed the idea that the federal government should get involved in flood control along the Big Sioux. The Corps informed valley residents that it was not opposed to private development along the river so long as the private projects did not straighten the river south of Westfield.[24] Again, the Corps’ primary concern was the possibility that cut-offs would increase flood heights at Sioux City.

The Floods Worsen

By the 1920s, the likelihood of federal involvement in flood control along the Big Sioux appeared all but dead. And even though flooding had become a serious problem by that decade, farmers did nothing to reduce the flood threat. Instead, they intensified the development of their lands.[25]

By this point in time, the Corps had a solid understanding as to why the Big Sioux had become so flood-prone. In 1924, the Corps’ Washington headquarters admitted, “The problem of regulating the Big Sioux River below the northern boundary of Iowa is fundamentally one of conserving and reclaiming agricultural lands and of adjusting the respective rights of land owners….”[26] In other words, flood abatement along the Big Sioux could only be achieved by placing some limits on private land use and instituting conservation measures to reduce runoff and soil erosion.

In 1927 a historic flood hit the Mississippi Valley south of Cairo, Illinois. The flood persuaded Congress to fund the most extensive series of river surveys in American history. The surveys became known collectively as the “308 reports.” In the most thorough analysis of the Big Sioux River to date, the Corps concluded that the Big Sioux should not be developed by the federal government for any purpose whatsoever. The Corps rejected the federal construction of dams, reservoirs, levees, and cut-offs anywhere along the river. The report stated that flood control is “not economically justifiable…hydroelectric development is impracticable…navigation is out of the question…and irrigation is not required.[27]

Since neither the federal government nor private landowners were willing to do anything about the flood situation along the Big Sioux, the river continued to flood. The river overtopped its banks in 1922, 1926, and again in 1928. In early March 1932, a string of ice jams in the river north of Sioux City forced cold water to flow out over the valley lowlands. In Union County, South Dakota, the Big Sioux spread so far afield that it resembled a gigantic lake.[28]

During the remainder of the drought-stricken Dirty Thirties, the Big Sioux did not experience any major floods. But in the 1940s and 1950s, the floods returned, spurred on by the advent of a wet precipitation cycle and the intensification of agricultural production across the basin during World War II. High water descended the valley in 1942, 1943, 1948, 1951, 1952, 1953, 1954, and 1957.[29]

In 1960, the Big Sioux flooded yet again. This flood broke records. Mrs. Conrad Falde, who lived on a farm west of Hawarden, Iowa, could hardly believe how high the water rose that year. She said, “We have lived here for thirty-five years…and we have never had a flood to compare with this one.”[30] A Corps official described the 1960 deluge as “the greatest in history.” He noted that the river rose so high that year because of the speed with which runoff entered the stream.[31] Of course, the rate that runoff entered the river had a lot to do with the fact that there was so little on the land to slow its movement.

Two years later, another major flood struck segments of the lower valley. By that time, a consensus had emerged among residents of the Big Sioux Valley that agriculture was the primary culprit in the repeated inundations.

Vic Clark, who served as the head of the Lower Big Sioux Watershed Association, a group that sought the straightening of the lower river, had no doubt that siltation of the channel and the raising of the river’s bed were the primary reasons for the frequent floods.[32] Another Big Sioux Valley resident who lived near Akron, Iowa, considered siltation the main cause of flooding along the river. He had determined that since the 1880s, portions of the valley near his home had been buried under four feet of eroded topsoil.[33] O.D. Hansen of Elk Point, South Dakota, was convinced that the river channel through southeast South Dakota and northwest Iowa had become clogged with silt because of erosion from the uplands.[34] Some valley residents had also witnessed firsthand where riverside vegetation had trapped the river’s silt, filled the river’s edges with mud, narrowed the channel, and further reduced the stream’s conveyance capacity.[35]

Even the Sioux City Journal, a local daily that had long catered to agricultural interests, acknowledged that farming across the basin had radically altered the river’s morphology and flow regime. In one article, the paper stated, “Old-timers, who have grown up in Sioux City and along the river, can tell you of the days when the river was clear and when the channel capacity was large enough to handle runoff from the watershed.”[36] Nils Aspaas, a farmer near Baltic, South Dakota, placed responsibility for the floods squarely on the shoulders of his fellow farmers. He stated, “Landowners in the lower valley…aren’t to blame for the floods. It is the landowners in the upper watersheds, emptying into the Big Sioux, who can help the most in preventing these floods through the use of soil conservation practices.”[37]

But there was no mention at the time in the basin’s newspapers, or amongst the region’s farm organizations, of implementing a program of better land stewardship to address the Big Sioux’s worsening floods. Instead, farm interests lobbied the Corps to address the flood problem. The various farm groups that lobbied the Corps had no interest in any flood control program that might in any way impinge on the individual farmer’s management of his private property. This explains why farmers pushed the Corps to do something about the flooding – the Corps’ projects would not require farmers to make even the tiniest of changes in land use. Instead, the Corps would focus its flood control efforts along the river’s main stem, while farmers continued to develop their land as they saw fit.

Following the 1960 flood, the Corps responded to the requests of the valley’s farmers for some sort of development scheme. In a dramatic reversal of the conclusions of its earlier 308 Report, the Corps proposed to develop the final fifty-five miles of the river from Akron, Iowa, to Sioux City. The plan called for channel cut-offs, channel widening, channel deepening, and channel clearing (of logs and other debris) at a cost of seven million dollars. If the project went ahead, the river below Akron would be transformed into a straight, wide ditch of uniform depth.[38]

The Corps proposal immediately ran into stiff opposition from national, regional, and local conservation groups, including the National Wildlife Federation, the Iowa Conservation Commission, the South Dakota Fish, Game, and Parks Department, the Izaak Walton League, and the Orange City Catfish Club. The members of these groups believed the project would destroy one of the last, large segments of fish and wildlife habitat in western Iowa and southeast South Dakota. The Iowa Conservation Commission’s Earl T. Rose said that if the Corps’ project went ahead, the lower Big Sioux would resemble the straightened lower Little Sioux, and that river “…is just a canal…There is no fishing, no hunting, no recreation on that stretch of river.” He noted that straightening had “virtually ruined” portions of the Skunk, Upper Iowa, and Nishnabotna rivers for hunting and fishing. He then remarked that, “They’ve made biological deserts out of our streams here in Iowa and we feel we should make an all-out effort against this stream straightening.”[39]

The Sioux City Chamber of Commerce favored the project but with reservations. Its leaders worried that the straightening of the Big Sioux would bring floodwaters down on their city at a faster rate and at higher levels.[40]

Despite intense opposition, the Corps proposal gained renewed traction in 1962, when South Dakota Senator George McGovern voiced his support for the Corps’ plan. McGovern argued that the wishes of the farming community should take precedence over the concerns of the conservationists. For McGovern, production and profit trumped ecology, public recreation, and aesthetics.[41]

Yet, even with McGovern’s backing, the project never gained enough public support to become a reality. There were just too many organizations and influential individuals who opposed it. Plus, the farming community was not united in its support. Some valley farmers did not want to forfeit any land to the project. Others did not want to pay the higher taxes required for the long-term upkeep of some of the engineering works. And a few farmers actually valued the unchannelized river’s natural beauty. Farmer Clare Lilly said, “…straightening the river would ruin everything.”[42] But what ultimately doomed the proposal was the opposition of two Iowa governors – Norman Erbe (R) and Harold Hughes (D). The Corps could not proceed with the project without the backing of Iowa’s top elected officials.

The defeat of the channel straightening project did not stop the Corps. It continued to seek the develop of the stream. One reason the Corps wanted to develop the Big Sioux in the 1960s, even though it had rejected development in the 1930s, had to do with institutional self-preservation. By the mid-1960s, the Corps had nearly completed all of its Missouri River dams, as well as the navigation channel south of Sioux City. Facing the likelihood of severe budget cuts as work along the Missouri came to an end, a Big Sioux development plan offered the Corps’ Omaha District a lifeline, ensuring years of additional work for its military and civilian engineers.

In 1969, the Big Sioux experienced its greatest flood to date. The Corps responded to the flood, and the public’s fear of future floods, by proposing the construction of five huge dams within the basin, including a gigantic structure across the main-stem at Flandreau, South Dakota, that would have measured 8,300 feet long and seventy-nine feet high. But with environmentalism on the ascendancy across the United States, and the farming community again divided on the merits of the proposal, there just wasn’t enough public support for such a massive remaking of the Big Sioux watershed. So, the Corps’ plans went nowhere.[43]

The Past, Present, and Future

The 1969 flood, like all the major floods to strike the Big Sioux since the dawn of agricultural settlement, came after a period of intense agricultural development within the basin. In the two and a half decades after World War II, Midwestern farmers increasingly relied on machines and chemicals to boost crop production.[44]

Although basin residents knew the reasons for the river’s repeated floods, the intensification of agriculture continued unabated in the decades after 1969. In the 1990s and early 2000s, hog and cattle operations increased significantly across the basin. By the 2010s, the three Iowa counties immediately east of the river became three of Iowa’s largest producers of hogs and cattle. At the end of 2017, Lyon, Sioux, and Plymouth counties held a total of 3,256,312 hogs and almost 725,000 cattle. Sioux County became one of the top five counties in the United States for the value of cattle and hog sales. The high value of sales resulted from the astronomical number of hogs and cattle in the county. Hogs outnumbered people by at least 36 to 1, while cattle outnumbered county residents by 12 to 1.[45]

Sioux County also had the highest percentage of land of any county in Iowa devoted to some form of agricultural production. Of the county’s 492,160 acres, 483,501 acres were in farms. And on those farms, 94% of the land grew crops, 2% of the land consisted of pasture, and 4% had been developed as feedlots, hog confinement facilities, sewage lagoons, homesteads, parking lots, and drainage ditches. Not surprisingly, the U.S. Department of Agriculture ranked Sioux County as one of the least likely counties in the United States to possess natural amenities, or the physical characteristics that contributed to quality of life. Of the 3,111 counties within the United States, Sioux County ranked 3,037 for natural amenities. Sioux County’s neighbor to the north ranked even lower. Only fifteen other counties in the U.S. had fewer natural amenities than Lyon County.[46] A land once covered in big bluestem and dotted with wetlands had been thoroughly subsumed by hogs, cattle, confinement buildings, muddy feedlots, manure ponds, and corn and soybean fields.

The millions of cattle and hogs across the Big Sioux basin produced a lot of beef, pork, and manure. In 2019, a University of Iowa researcher estimated that Iowa’s 110 million chickens, hogs, turkeys, and cattle, along with its 3.2 million people, excreted the same amount of fecal waste as 168 million people. Predictably, the northwest Iowa counties of Lyon, Sioux, and Plymouth were three of the largest producers of fecal waste within the state. Following a heavy rain, the region’s cattle feedlots resembled cess pools, which drained bacteria-rich muck into the Big Sioux or one of its tributaries. The millions of hogs being fattened in confinement buildings produced a mind-boggling quantity of manure. Confinement operators stored that manure in holding ponds. Once those holding ponds reached capacity, hog confinement operators removed the manure, then sprayed it or flung it over their fields, often in the winter months after the ground had frozen as hard as concrete. When the winter snows melted away, and the spring rains commenced, a sizable portion of that manure slid into the Big Sioux. By the 2010s, the Big Sioux had become so polluted by hog and cattle manure that scientists worried about the effect of the pollution on human health. In a river teeming with pathogens, there was the real possibility of serious disease outbreaks.[47]

And the river continued to flood – spectacularly. The volume of water descending the Big Sioux during the flood of 1993 topped the volume of the 1969 flood; and the 2014 flood topped the flood of 1993. The recent record floods have been exacerbated by climate change and the rain events that accompany it. In addition, the near total elimination of the land’s natural water storage capacity, especially its water absorbing prairie grasses and wetlands, means the heavy rains resulting from climate change rapidly drain into the Big Sioux.

Iowa once possessed twenty-five million acres of grassland. By the 1990s, the state had only “about 30,000 acres of prairie.”[48] Before European-American colonization, Iowa held approximately four million acres of wetlands; by the 1990s, the state contained one-tenth of that amount, or about 422,000 acres.[49]

At present, there is no indication that even a fraction of the Big Sioux basin’s former prairie lands or wetland acres will be re-established. Thus, major floods are sure to descend the Big Sioux in the years ahead.

Pollution, increased turbidity, and repeated floods devastated the Big Sioux’s native fish species, such as northern pike and smallmouth bass, while benefiting invasive species like the German carp and Asian carp. Aided by flood flows, the Asian carp is presently expanding its range within the Big Sioux basin; all the while diminishing the food and habitat available to native species. Consequently, the prognosis for the Big Sioux’s native fish is grim.[50]

The modern Big Sioux is biologically depleted, hydrologically unstable, and dangerously polluted. The river did not become one of America’s most ecologically and hydrologically compromised rivers from human neglect, ignorance, or coincidence. And its current condition is not the result of some “Tragedy of the Commons.” Rather, the Big Sioux is in such a sorry state because of individual human choice and action. European-American agriculturalists have knowingly chosen to squeeze every available resource from the river and its basin. First, they converted the prairie to cropland. Then they drained the wetlands, laid tiles under their land, and straightened the river’s tributaries. Later, they took even more from the river and its basin by building thousands of hog confinements and feedlots, and placing millions of hogs and cattle within those inhumane spaces. And finally, they injected the land with herbicides, pesticides, chemical fertilizers, and manure, which not only increased crop yields but also worsened stream pollution.

By any objective measure, the emphasis on maximum production of everything from hogs to cattle to corn has left the Big Sioux in a dismal condition. And yet, there is no indication that the ethos of maximum production will be abandoned or even modified to allow the river and basin to recover some semblance of biological diversity, water quality, or hydrological stability. Instead, it appears as though farmers within the basin will continue to follow the path first established by their forebearers in the nineteenth century.

In the aftermath of the 1960 flood, a meeting was held in Sioux City to discuss possible flood control measures along the Big Sioux. Lester Berner of the South Dakota Game, Fish, and Parks Department attended the gathering, as did several valley farmers. During the course of the meeting, Berner challenged the farmers in the audience to consider how their land use practices, especially their emphasis on maximizing the production of corn, contributed to flooding along the river. At one point, a frustrated Berner asked the farmers a rhetorical question, “…[do] we need more corn?” Keith Knapp, a Big Sioux Valley farmer, decided that Berner’s question actually required a response, he unashamedly asserted, “…we always need more corn.”[51]


[1] Maria Audubon, Audubon and His Journals, Volume I, (New York: Dover Publication, Inc., 1960). 489.

[2] John Hult, “Precision Testing Shows Danger in Big Sioux,” Sioux Falls Argus Leader,  February 20, 2016; Bart Pfankuch, “Studies Reveal Health Hazards in Big Sioux River, Rapid Creek,” Sioux Falls Argus Leader, August 29, 2018.

[3] “South Dakota’s Big Sioux Among Dirtiest River in Nation,” Rapid City Journal, May 7, 2012.

[4] “Myhre: Asian Carp May Ruin Our Fisheries,” Sioux City Journal, April 29, 2015; “Asian Carps Invade the Rivers of Eastern South Dakota, Concerning GFP Officials,” Nick Lowrey, Sioux Falls Argus Leader, March 8, 2014; “DNR Biologist Addresses Asian Carp Concerns,” Renee Wielenga, Sioux Center News, July 20, 2016; “Outside: Big or Small, Asian Carp Mean Trouble for South Dakota Waters,” Kevin Woster, Rapid City Journal, July 18, 2013.

[5] Fred Masek, “Big Sioux’s Mighty Flood,” South Dakota Magazine, March/April 1990,

[6] Donald Dean Parker, Pioneering in the Upper Big Sioux Valley, Medary, Sioux Falls, Dell Rapids, Flandreau, Brookings, Watertown, (Self-Published, 1967), 13.

[7] Department of the Army, U.S. Army Corps of Engineers, Big and Little Sioux Rivers Iowa and South Dakota, 72d Congress, 1st Session, House Document 189, (Washington, GPO, 1932), 4-5. Henceforth referenced as 308 Report.

[8] 308 Report, Appendix III.

[9] Pioneering in the Upper Big Sioux Valley, 232.

[10] U.S. Army Corps of Engineers, Missouri River Division, Hydrological and Hydraulic Data Files, Big Sioux River, Box 108, Ref. No. 07773J0832, Folder: Lower Big Sioux (Mouth to Rock River) Design Investigations, National Archives at Kansas City, Kansas City, Missouri, 2.

[11] Sioux City Clip Files, “Rivers, Big Sioux River, Book 1,” Sioux City Public Library; “Remember When the Big Sioux was Clear and Peaceful,” Sioux City Journal, July 26, 1954.

[12] State Department of History, South Dakota Historical Collections, Volume IX, (Pierre: Hipple Printing Company, 1918), 366.

[13] Lower Big Sioux (Mouth to Rock River) Design Investigations, 1.

[14] Gary E. Moulton, ed., The Journals of the Lewis and Clark Expedition, Volume 2, August 30, 1803 – August 24, 1804, (Lincoln: University of Nebraska Press, 1986), 483-484; Gary E. Moulton, ed., The Journal of Patrick Gass, Volume 10, May 14, 1804 – September 23, 1806, (Lincoln: University of Nebraska Press, 1996), 29, 31.

[15] 308 Report, Table 1-6.

[16] “Remember When the Big Sioux was Clear and Peaceful,” Sioux City Journal, July 26, 1954.

[17] “Akron Farmer Presents,” Sioux City Journal, April 7, 1962; “Remember When the Big Sioux was Clear and Peaceful,” Sioux City Journal, July 26, 1954.

[18] Department of Agriculture, Office of Experiment Stations Drainage Investigation, Report Upon the Reclamation of the Overflowed Lands in the Valley of the Big Sioux River, Plymouth County, Iowa, and Union County, South Dakota, by Fred F. Shafer, Drainage Engineer, October 1910, p. 8.

[19] 308 Report, 7.

[20] Report Upon the Reclamation of the Overflowed Lands in the Valley of the Big Sioux River, 8.

[21] 308 Report, Table 3, Table 7.

[22] Department of the Army, U.S. Army Corps of Engineers, Big Sioux River, S. Dak. And Iowa, Survey, 61st Congress, 2d Session, House Document 408, May 31, 1909.

[23] Record Group 77, Office of the Chief of Engineers, War Department, Omaha District, General Correspondence, 1900-1942, NAID: 76018478, Letter, Secretary of War to George C. Scott, April 2, 1915.

[24] Record Group 77, Office of the Chief of Engineers, War Department, Kansas City District, Big Sioux River, Miscellaneous Folder, 40/69, Letter, Willard Young to Miller Miller Co., March 28, 1919.

[25] 308 Report, Table 2.

[26] Record Group 77, Office of the Chief of Engineers, War Department, Omaha District, General Correspondence, 1900-1942, NAID: 76018478, Office of the Chief of Engineers, April 24, 1924.

[27] Ibid., 19, i, ii.

[28] “Tribune Photographers Take Airplane Photos of Big Sioux Flood,” Sioux City Journal, March 3, 1932.

[29] “Sioux Out of Banks, Floods Riverside Area,” Sioux City Journal-Tribune, June 6, 1942; “Big Sioux Slashes Shoreline at Riverside Park,” Sioux City Journal, March 31, 1943.

[30] “Highest Crest in Ten Years on Big Sioux,” Sioux City Journal, March 31, 1960.

[31] “Big Sioux Controversy Just ‘Misunderstanding,’” Sioux City Journal, March 15, 1962.

[32] “Big Sioux Farmers Ask Flood Control Project,” Sioux City Journal, August 13, 1956.

[33] “Akron Farmer Presents,” Sioux City Journal, April 7, 1962.

[34] “Public Given First Look at Iowa Unit’s Study of Proposal,” Sioux City Journal, June 26, 1962.

[35] “Tours Flood Plains of Big Sioux River,” Sioux City Journal, April 21, 1963.

[36] “Remember When the Big Sioux was Clear and Peaceful,” Sioux City Journal, July 26, 1954.

[37] “The Big Sioux Story,” Sioux City Journal, July 19, 1954.

[38] “Expect Engineers Control Program to Reduce Flooding Substantially,” Sioux City Journal, June 1, 1961; “Conservationists, Farmers in Clash at Big Sioux Meet,” Sioux City Journal, November 10, 1961.

[39] “A $7 Million Big Sioux Job is Proposed,” Des Moines Register, December 3, 1961.

[40] “Conservations, Farmers in Clash at Big Sioux Meet,” Sioux City Journal, November 10, 1961; “A $7 Million Big Sioux Job is Proposed,” Des Moines Register,  December 3, 1961.

[41] “Tours Flood Plains of Big Sioux River,” Sioux City Journal, April 21, 1963; “Optimistic on Control of Big Sioux,” Sioux City Journal, March 19, 1964.

[42] “Will the Big Sioux Become a Wasteland,” Des Moines Register, November 10, 1968.

[43] “Hearing May 28 on $109 Million Big Sioux Plan,” Sioux City Journal, May 14, 1969.

[44] “Big Sioux Problems Discussed,” Sioux City Journal, March 27, 1964.

[45] U.S. Department of Agriculture, 2017 Census of Agriculture, County Profile, Sioux County, Iowa,; U.S. Department of Agriculture, 2017 Census of Agriculture, County Profile, Lyon County, Iowa,; U.S. Department of Agriculture, 2017 Census of Agriculture, County Profile, Plymouth County, Iowa,

[46] U.S. Department of Agriculture, 2017 Census of Agriculture, County Profile, Sioux County, Iowa,; Christopher Ingraham, “Every County in America Ranked by Scenery and Climate,” Washington Post, August 17, 2015.

[47] Donnell Eller, “50 Shades of Brown: Iowa Ranks No.1 in, Ahem, No.2, UI Researcher Calculates,” Des Moines Register, June 10, 2019; Bart Pfankuch, “Studies Reveal Health Hazards in Big Sioux River, Rapid Creek,” Sioux Falls Argus Leader, August 29, 2018.

[48] James J. Dinsmore, A Country So Full of Game: The Story of Wildlife in Iowa, (Iowa City: University of Iowa Press, 1994), 181.

[49] Ibid., 179, 182.

[50] “Myhre: Asian Carp May Ruin Our Fisheries,” Sioux City Journal, April 29, 2015; “Asian Carps Invade the Rivers of Eastern South Dakota, Concerning GFP Officials,” Nick Lowrey, Sioux Falls Argus Leader, March 8, 2014; “DNR Biologist Addresses Asian Carp Concerns,” Renee Wielenga, Sioux Center News, July 20, 2016; “Outside: Big or Small, Asian Carp Mean Trouble for South Dakota Waters,” Kevin Woster, Rapid City Journal, July 18, 2013.

[51] “Conservationists, Farmers Clash at Big Sioux Meet,” Sioux City Journal, November 10, 1961.

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