Missouri River facts for kids
The Missouri River is a very important river in the United States. It flows through the middle and western parts of the country. It's the longest river in the nation!
The Missouri River starts high up in the Rocky Mountains in southwestern Montana. From there, it flows east and then south for about 2,341 miles (3,767 km). It finally joins the mighty Mississippi River north of St. Louis, Missouri.
This huge river system drains a massive area of land, over 500,000 square miles (1,300,000 km²). This area includes parts of ten U.S. states and two Canadian provinces. Even though it's a branch of the Mississippi, the Missouri River is actually a bit longer and carries a similar amount of water. When you combine the Missouri with the lower Mississippi River, they form the fourth-longest river system in the world!
For more than 12,000 years, people have relied on the Missouri River. It has provided food and a way to travel. More than ten large groups of Native Americans lived in this river basin. Most of them were nomadic, meaning they moved around. They depended on the huge herds of bison (buffalo) that roamed the Great Plains.
Europeans first saw the river in the late 1600s. The region was controlled by Spain and France before the United States bought it in the Louisiana Purchase.
The Missouri River was a main route for people moving west in the 1800s. The fur trade helped explorers map the area. Then, many pioneers started heading west in the 1830s. They traveled first by covered wagon and later by steamboats on the river. Sadly, conflicts between settlers and Native Americans in the area led to some very difficult wars.
In the 1900s, the Missouri River basin was developed a lot. People built dams for irrigation, to control floods, and to make electricity. There are fifteen dams on the main part of the river, and hundreds more on its smaller branches. Parts of the river were also straightened to make it easier for boats to travel. This made the river almost 200 miles (320 km) shorter than it used to be.
Today, the lower Missouri valley is a busy area with many farms and factories. But all this development has affected the wildlife, fish, and water quality.
Contents
Where the Missouri River Flows
The Missouri River officially begins in Missouri Headwaters State Park near Three Forks, Montana. Here, three streams come together to form its start:
- The longest stream starts near Brower's Spring in southwest Montana. It's about 9,100 feet (2,774 m) above sea level in the Rocky Mountains. This stream flows into the Red Rock, then the Beaverhead River, and finally joins the Big Hole to form the Jefferson River.
- The Firehole River starts in Yellowstone National Park in Wyoming. It joins the Gibbon River to form the Madison River.
- The Gallatin River also flows out of Yellowstone National Park. It joins the Missouri a little downstream from where the Jefferson and Madison meet.
After its official start, the Missouri River flows through Canyon Ferry Lake, a reservoir. Then it goes northeast to Great Falls. Here, the river drops over the Great Falls of the Missouri, which is a series of five big waterfalls.
Next, the river winds east through a beautiful area of canyons and badlands called the Missouri Breaks. It gets water from the Marias River and then widens into the Fort Peck Lake reservoir. After passing through the Fort Peck Dam, the Milk River joins it from the north.
As the Missouri flows east through the plains of eastern Montana, it enters North Dakota. Here, the Yellowstone River joins it from the southwest. The Yellowstone is actually the biggest branch of the Missouri by how much water it carries!
The Missouri then flows past Williston and into Lake Sakakawea, a reservoir made by Garrison Dam. Below the dam, it flows south to Bismarck, the capital of North Dakota. It then slows down into the Lake Oahe reservoir. As it continues south into South Dakota, the Grand, Moreau, and Cheyenne Rivers all join the Missouri from the west.
The Missouri then turns southeast and flows through the Great Plains. It forms the border between South Dakota and Nebraska. The James River joins from the north. At Sioux City, the Big Sioux River comes in from the north. After that, the Missouri forms the border between Iowa and Nebraska.
It flows south to Omaha, where it receives its longest branch, the Platte River, from the west. Further downstream, it forms the border between Nebraska and Missouri, and then between Missouri and Kansas. The Missouri turns east at Kansas City, where the Kansas River enters from the west.
East of Kansas City, the Grand River joins it. The river passes south of Columbia and receives the Osage and Gasconade Rivers from the south. Finally, the river flows around the north side of St. Louis to join the Mississippi River.
The Missouri River's Huge Basin
The Missouri River's drainage basin is like a giant funnel that collects water from a huge area. It covers almost one-sixth of the United States! This area is similar in size to the Canadian province of Quebec. It stretches from the Rocky Mountains in the west to the Mississippi River Valley in the east.
The Missouri River provides about 45% of the water that flows into the Mississippi River past St. Louis. During dry periods, it can provide as much as 70% of the water.
In 1990, about 12 million people lived in the Missouri River basin. This included all of Nebraska and parts of Colorado, Iowa, Kansas, Minnesota, Missouri, Montana, North Dakota, South Dakota, Wyoming, and even small parts of Canada. The biggest city in the basin is Denver, Colorado. Other major cities include Omaha, Nebraska, Kansas City, Missouri-Kansas City, Kansas, and the St. Louis area.
The Missouri River basin is also a huge farming area. About one-fourth of all the farmland in the United States is here! It produces more than a third of the country's wheat, flax, barley, and oats. A lot of the land is also used for raising livestock, especially cattle.
The elevation in the basin changes a lot. It's just over 400 feet (122 m) at the river's mouth and goes up to 14,293 feet (4,357 m) at the top of Mount Lincoln in Colorado. The land generally slopes gently from west to east.
The weather in the Missouri River basin can be very different. It has a continental climate, meaning warm, wet summers and cold, harsh winters. Most of the basin gets about 8 to 10 inches (200 to 250 mm) of rain each year. But the western mountains and southeastern Missouri can get as much as 40 inches (1,000 mm).
Major Rivers Joining the Missouri
Over 95 important rivers and hundreds of smaller streams flow into the Missouri River. Most of the larger ones join closer to the Missouri's mouth. Most rivers in the Missouri basin flow from west to east, following the slope of the Great Plains. However, some eastern rivers like the James and Big Sioux flow from north to south.
The biggest rivers joining the Missouri by how much water they carry are the Yellowstone (in Montana and Wyoming), the Platte (in Wyoming, Colorado, and Nebraska), and the Kansas and Osage (in Kansas and Missouri). The Yellowstone River actually has the highest flow, even though the Platte is longer.
| Longest tributaries of the Missouri River | ||||||
|---|---|---|---|---|---|---|
| Name | Length | Watershed | Discharge | |||
| mi | km | mi2 | km2 | ft3/s | m3/s | |
| Platte River | 1,061 | 1,708 | 84,910 | 219,900 | 7,037 | 199 |
| Kansas River | 749 | 1,205 | 59,500 | 154,000 | 7,367 | 209 |
| Milk River | 729 | 1,170 | 15,300 | 39,600 | 618 | 17.5 |
| James River | 710 | 1,140 | 21,500 | 55,700 | 646 | 18.3 |
| Yellowstone River | 702 | 1,130 | 70,000 | 180,000 | 13,800 | 391 |
| White River | 580 | 933 | 10,200 | 26,420 | 570 | 16.1 |
| Niobrara River | 568 | 914 | 13,900 | 36,000 | 1,720 | 48.7 |
| Little Missouri River | 560 | 900 | 9,550 | 24,700 | 533 | 15.1 |
| Osage River | 493 | 793 | 14,800 | 38,300 | 11,980 | 339 |
| Big Sioux River | 419 | 674 | 8,030 | 20,800 | 1,320 | 37.4 |
The table on the right shows the ten longest rivers that flow into the Missouri. The length is measured from the farthest source, even if the river has a different name at its start. For example, the Kansas River's main part is 148 miles (238 km) long. But if you include its longest starting branches, it's 749 miles (1,205 km) long!
If you measure the Missouri River from its very farthest source at Brower's Spring, it's about 2,639 miles (4,247 km) long. When combined with the lower Mississippi, this makes it part of the fourth-longest river system in the world, at 3,745 miles (6,027 km).
How Much Water Flows in the Missouri?
The Missouri River flows through a mostly dry region. Because of this, the amount of water it carries is lower and changes more than other long rivers in North America. Before dams were built, the river used to flood twice a year. Once in spring from melting snow on the plains, and again in June from snowmelt and summer storms in the Rocky Mountains. The June floods were much bigger and more destructive.
Today, there are over 17,000 reservoirs (man-made lakes) on the Missouri and its branches. These reservoirs help control floods by holding back water. They also make sure there's enough water flowing during dry times. However, a lot of water evaporates from these reservoirs, which reduces the river's overall flow.
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The average flow of the Missouri River at Hermann, Missouri, near its mouth, is about 87,520 cubic feet per second (2,478 m³/s). The most water ever recorded was over 750,000 cubic feet per second (21,000 m³/s) during a huge flood in 1993. The least water recorded was only 602 cubic feet per second (17 m³/s) in 1963, caused by ice blocking the river.
How the River Was Formed
The Rocky Mountains, where the Missouri River begins, were formed millions of years ago. This mountain-building event created the landscape for the huge river system we see today. Snow and ice melting from the Rockies provide most of the water for the Missouri and its branches.
The Missouri River and many of its branches flow across the Great Plains. They cut into layers of rock and sediment that were laid down over millions of years. These layers include the Ogallala Aquifer, a huge underground water source.
Before the last Ice age, the Missouri River was probably in three separate parts. One part flowed north into Hudson Bay, and the other parts flowed east. But as the Earth got colder and glaciers grew, the ice sheets pushed the Missouri River southeast. This made it connect into one single river system that flows to the Mississippi.
The Missouri River's nickname, the "Big Muddy," comes from the huge amount of sediment (mud and sand) it used to carry. Before dams were built, the river moved about 175 to 320 million tons of sediment each year! This mud came from the river's floodplain as it changed course and eroded its banks. However, building dams and straightening the river has greatly reduced how much sediment it carries today.
Early People Along the River
Scientists believe that people first lived in the Missouri River basin between 10,000 and 12,000 years ago. The Missouri River was an important path for these early groups of people. Many of them eventually settled in the Ohio Valley and lower Mississippi River Valley. But many, like the Mound builders, stayed along the Missouri. They became the ancestors of the later Native American tribes of the Great Plains.
Native American groups who lived along the Missouri River had plenty of food, water, and shelter. Many animals, like the buffalo, lived on the plains. These animals provided meat, clothing, and other daily items. The river's floodplain also had many plants for food.
Some of the major tribes along the Missouri River included the Otoe, Missouria, Omaha, Ponca, Lakota, Arikara, Hidatsa, and Mandan. The river was used for trade and travel, and it often formed borders between different tribes. Many tribes were semi-nomadic, moving between summer and winter camps.
A group of walled Mandan, Hidatsa, and Arikara villages in the Dakotas was a very important trading center. Thousands of people lived there. Later, early French and British explorers used it as a trading post. When horses were introduced to the Missouri River tribes, their way of life changed a lot. Horses allowed them to travel farther for hunting, communication, and trade.
Millions of American bison used to roam the plains of the Missouri River basin. Most Native American nations relied heavily on bison for food. Their hides and bones were used for many things. However, after Europeans arrived, both the bison and Native American populations quickly declined. Huge numbers of bison were hunted, and diseases like smallpox greatly reduced Native American populations. Without their main food source, many Native Americans were forced to move to reservations.
European Explorers Arrive
In 1673, two French-Canadian explorers, Louis Jolliet and Jacques Marquette, were the first Europeans to discover the Missouri River. They described it as a powerful, muddy river. They called it Pekitanoui, which was a local Native American name. They didn't explore the Missouri much beyond its mouth.
In 1682, France claimed the land on the western side of the Mississippi River, which included the lower Missouri. But the Missouri itself wasn't really explored until 1714. That's when Étienne de Veniard, Sieur de Bourgmont led an expedition. He likely traveled as far as the Mandan villages in North Dakota. Bourgmont later published the first known document to use the name "Missouri River." Many of the names he gave to the river's branches, often from Native American tribes, are still used today.
Bourgmont established Fort Orleans in 1723, which was the first European settlement on the Missouri River. He also led an expedition to get the Comanche tribe's help against the Spanish, who wanted to control the Missouri. In 1725, Bourgmont took chiefs from several Missouri River tribes to visit France.
The French and Indian War started in 1754. After France lost the war in 1763, they gave their Canadian lands to the British. They also secretly gave Louisiana, including the Missouri River, to Spain. Spain didn't explore the Missouri much at first, letting French traders continue their work.
But then, Spanish explorers heard that British traders were in the upper Missouri River area. So, in 1795, Spain created the "Missouri Company" and offered a reward to the first person to reach the Pacific Ocean via the Missouri. Explorers like James MacKay and John Evans made the first accurate map of the upper Missouri River.
In 1800, Spain secretly gave Louisiana back to Napoleon's France. Then, in 1803, President Thomas Jefferson wanted to buy the port of New Orleans from France. Instead, Napoleon offered to sell all of Louisiana, including the Missouri River, for $15 million. This deal, called the Louisiana Purchase, doubled the size of the United States!
In 1803, Jefferson asked Meriwether Lewis to explore the Missouri River and find a water route to the Pacific Ocean. People thought there might be a short connection between the Missouri and the Columbia River system, which flows to the Pacific.
Meriwether Lewis and William Clark started their famous expedition in 1804. They became the first Europeans to travel the entire length of the Missouri and reach the Pacific Ocean. They didn't find a direct water route, but their maps of the Pacific Northwest were very important for future explorers. They also met many Native American tribes and wrote detailed reports about the area's climate, plants, animals, and geology. Many names of places in the upper Missouri basin today came from their expedition.
The American Frontier and the Missouri
Fur Trade and Exploration
In the early 18th century, fur trappers came to the northern Missouri River basin looking for beaver and river otter. The sale of their furs was a big business. These trappers came from Canada and the United States.
In 1806, Lewis and Clark returned with exciting news. Their journals described lands full of buffalo, beaver, and river otter. In 1807, explorer Manuel Lisa organized an expedition that led to a huge growth in the fur trade. Lisa and his crew traveled up the Missouri and Yellowstone Rivers. They traded goods for furs with Native American tribes and built a fort.
This business grew quickly. In 1809, the St. Louis Missouri Fur Company was founded. Later, the American Fur Company built Fort Union in 1828. It became the main center for the fur trade in the upper Missouri basin.
Fur trapping happened all over the Rocky Mountains. Trappers from different companies worked in the Missouri watershed and other river systems. These trappers, also called mountain men, created trails through the wilderness. These trails were later used by pioneers and settlers heading west. The need to transport thousands of beaver pelts helped start river travel on the Missouri.
By the late 1830s, the fur industry began to decline. Silk became more popular than beaver fur. Also, the beaver population was greatly reduced by too much hunting. Native American attacks on trading posts also made it dangerous. The fur trade mostly ended in the Great Plains around 1850. But its legacy was important: it helped open up the American West for settlers.
Settlers and Pioneers Head West
The Missouri River was like a border for the American frontier in the 1800s. The main trails for moving west all started on the river. These included the California, Mormon, Oregon, and Santa Fe trails. The first part of the Pony Express involved a ferry across the Missouri at St. Joseph, Missouri.
Many emigrants arrived at the start of the First transcontinental railroad by taking a ferry across the Missouri between Council Bluffs, Iowa, and Omaha. The Hannibal Bridge was the first bridge to cross the Missouri River in 1869. Its location helped Kansas City become the biggest city on the river upstream from St. Louis.
From the 1830s to the 1860s, over 500,000 people started their journey west from Independence, Missouri. They had many reasons to go, like economic problems or the discovery of gold. Most of them traveled up the Missouri to Omaha, Nebraska. From there, they would travel along the Platte River. The Platte was too shallow for boats, but it provided water for the pioneers. Covered wagons were the main way to travel until steamboat service started in the 1850s.
In the 1860s, gold discoveries in Montana, Colorado, and Wyoming brought another wave of people. Most goods and passengers were transported by boat on the Missouri and Kansas Rivers. This journey upstream could take 150 days. The gold rushes led to many people settling in the Rocky Mountains.
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As settlers moved onto the Great Plains, they often had conflicts with Native American tribes over land. This led to many battles and wars. The U.S. government made treaties with the tribes, setting aside land for them. But these treaties were often broken, leading to more wars. Over 1,000 battles were fought before the tribes were forced onto reservations.
One example was Red Cloud's War, fought over the Bozeman Trail. The Lakota and Cheyenne tribes fought against the U.S. Army and won. In 1868, the Treaty of Fort Laramie was signed. It was supposed to protect lands like the Black Hills for Native Americans.
However, this peace didn't last. The Great Sioux War of 1876 started when American miners found gold in the Black Hills. Settlers moved onto these lands, and Native Americans attacked them. U.S. troops were sent in, leading to many bloody battles. The war ended with an American victory, and the Black Hills were opened for settlement. Native Americans in that region were moved to reservations.
The Era of Dam Building
In the late 1800s and early 1900s, many dams were built on the Missouri River. This changed 35% of the river into a series of reservoirs. Dams were built because people needed electricity in rural areas. Also, floods and droughts were causing problems for growing towns and farms along the lower Missouri.
Between 1890 and 1940, five dams were built near Great Falls to make electricity from the Great Falls of the Missouri. Black Eagle Dam, built in 1891, was the first dam on the Missouri. The largest of these five dams, Ryan Dam, was built in 1913.
Other private companies also started building dams on the Missouri River above Great Falls. For example, Hauser Dam was finished in 1907 but failed in 1908, causing huge floods downstream. It was rebuilt in 1910 and still stands today. Holter Dam was completed in 1918. Its reservoir flooded the beautiful Gates of the Mountains, a canyon described by Meriwether Lewis.
In 1949, the U.S. Bureau of Reclamation (USBR) began building the modern Canyon Ferry Dam. This dam helps control floods in the Great Falls area.
[ The Missouri's temperament was as ] "uncertain as the actions of a jury or the state of a woman's mind".
— Sioux City Register, March 28, 1868
The Missouri basin had several big floods around the early 1900s, especially in 1844, 1881, and 1926–1927. In 1940, as part of the Great Depression-era New Deal, the U.S. Army Corps of Engineers (USACE) completed Fort Peck Dam in Montana. This huge project created jobs and helped control floods in the lower Missouri River.
However, Fort Peck only controls water from 11% of the Missouri River basin. It didn't stop a severe flood in 1943 that damaged factories in Omaha and Kansas City during World War II.
Because of the flooding, the U.S. Congress passed the Flood Control Act of 1944. This allowed the USACE to develop the Missouri River on a massive scale. They created the Pick–Sloan Missouri Basin Program (Pick–Sloan Plan). This plan involved building large dams on the main part of the Missouri for flood control and electricity. It also included many smaller dams on its branches for irrigation.
In the 1950s, construction began on five more mainstem dams: Garrison, Oahe, Big Bend, Fort Randall, and Gavins Point. Along with Fort Peck, these dams now form the Missouri River Mainstem System.
Building these dams had a big impact on Native American groups. Their reservations often included fertile land in the floodplains, which was taken for the dams. For example, 150,000 acres (60,703 ha) of land were taken from the Fort Berthold Indian Reservation for the Garrison Dam. The tribes were forced to accept a settlement for their land.
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The six dams of the Mainstem System (Fort Peck, Garrison, Oahe, Big Bend, Fort Randall, and Gavins Point) are some of the largest dams in the world. Their reservoirs are also among the biggest in the United States. Together, they can store more than three years' worth of the river's flow! This makes it the largest reservoir system in the U.S. These dams also help control floods and provide water for irrigation to nearly 7,500 square miles (19,425 km²) of land. The power plants at these dams generate a lot of electricity each year.
| Dams on the Missouri River | |||||
|---|---|---|---|---|---|
| Dam | State(s) | Height | Reservoir | Capacity (Acre.ft) |
Capacity (MW) |
| Toston | MT | 56 ft (17 m) |
3,000 | 10 | |
| Canyon Ferry | MT | 225 ft (69 m) |
Canyon Ferry Lake | 1,973,000 | 50 |
| Hauser | MT | 80 ft (24 m) |
Hauser Lake | 98,000 | 19 |
| Holter | MT | 124 ft (38 m) |
Holter Lake | 243,000 | 48 |
| Black Eagle | MT | 13 ft (4.0 m) |
Long Pool | 2,000 | 21 |
| Rainbow | MT | 29 ft (8.8 m) |
1,000 | 36 | |
| Cochrane | MT | 59 ft (18 m) |
3,000 | 64 | |
| Ryan | MT | 61 ft (19 m) |
5,000 | 60 | |
| Morony | MT | 59 ft (18 m) |
3,000 | 48 | |
| Fort Peck | MT | 250 ft (76 m) |
Fort Peck Lake | 18,690,000 | 185 |
| Garrison | ND | 210 ft (64 m) |
Lake Sakakawea | 23,800,000 | 515 |
| Oahe | SD | 245 ft (75 m) |
Lake Oahe | 23,500,000 | 786 |
| Big Bend | SD | 95 ft (29 m) |
Lake Sharpe | 1,910,000 | 493 |
| Fort Randall | SD | 165 ft (50 m) |
Lake Francis Case | 5,700,000 | 320 |
| Gavins Point | NE SD |
74 ft (23 m) |
Lewis and Clark Lake | 492,000 | 132 |
| Total | 76,436,000 | 2,787 | |||
The table on the left lists all fifteen dams on the Missouri River. The dams marked in yellow are smaller dams that generate electricity. All the dams are on the upper half of the river, above Sioux City. The lower part of the river has no dams because it has been used for shipping for a long time.
Traveling on the Missouri River
[ Missouri River shipping ] "never achieved its expectations. Even under the very best of circumstances, it was never a huge industry".
— Richard Opper, former executive director
Missouri River Basin Association
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People have traveled on the Missouri River for thousands of years. Native Americans used canoes and bull boats. The first steamboat on the Missouri was the Independence in 1819. By the 1830s, large boats were regularly carrying mail and goods between Kansas City and St. Louis. Some even went much farther upstream.
During the fur trade, steamboats and keelboats traveled almost the entire length of the Missouri. They carried furs to and from the trappers' areas. This led to the development of special boats called Missouri River mackinaws for carrying furs. These boats could only travel downstream, so they were taken apart and sold for wood when they reached St. Louis.
Boat travel increased in the 1850s, carrying pioneers, emigrants, and miners. Steamboat navigation was at its peak in 1858, with over 130 boats working full-time. Side-wheeler steamboats were preferred because they were easier to steer than the larger sternwheelers used on the Mississippi.
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However, traveling on the Missouri was dangerous. Before the river was controlled, its changing water levels and huge amounts of sediment caused about 300 boats to be wrecked. The average lifespan of a ship on the Missouri was only about four years.
The development of railroads marked the end of steamboat travel on the Missouri. Trains were faster and more efficient. By the 1890s, there were almost no steamboats left. However, transporting farm products and mining materials by barge saw a comeback in the early 1900s.
Since the early 1900s, the Missouri River has been changed a lot for water transport. About 32% of the river now flows through straightened channels. In 1912, the USACE was allowed to keep the Missouri at a depth of 6 feet (1.8 m) from Kansas City to its mouth. They did this by building levees and wing dams to make the river flow in a straight, narrow channel. These changes have made the river shorter, from about 2,540 miles (4,088 km) in the late 1800s to 2,341 miles (3,767 km) today.
The dams built on the Missouri under the Pick-Sloan Plan helped with navigation. The large reservoirs provide a steady flow of water to keep the navigation channel open all year. They can also stop most of the river's annual floods.
In 1945, the USACE began a project to make the river's navigation channel 300 feet (91 m) wide and 9 feet (2.7 m) deep. They built rock dikes to direct the river's flow and remove sediment. They also cut off bends in the river and dredged the riverbed. However, the Missouri has often been difficult to control. In 2006, commercial barges got stuck because the channel was too shallow.
In 1929, people thought that 15 million tons of goods would be shipped on the river each year. But shipping traffic has been much lower than expected. From 1994 to 2006, only about 683,000 tons were shipped each year.
Most of the barge traffic on the Missouri River today carries sand and gravel from the lower 500 miles (805 km) of the river. The rest of the shipping channel is not used much by commercial boats.
For navigation, the Missouri River is divided into two parts. The Upper Missouri River is north of Gavins Point Dam. The Lower Missouri River is the 840 miles (1,352 km) below Gavins Point until it meets the Mississippi. The Lower Missouri River has no dams or locks. But it has many wing dams that help barges travel by directing the river's flow into a channel.
Why River Traffic Has Declined
The amount of goods shipped by barges on the Missouri River has dropped a lot since the 1960s. The USACE thought it would increase, but the opposite happened. One big reason is competition from other ways to transport goods, mainly railroads. Also, the USACE has not always been able to keep the navigation channel at the right depth.
Efforts are being made to bring back shipping on the Missouri River. River transport is efficient and cheap for moving farm products. Solutions like making the navigation channel wider and releasing more water from reservoirs during the shipping season are being considered.
In 2010, shipments increased a bit, but then the huge floods in 2011 closed parts of the river to boat traffic. This washed away hopes for a big comeback.
Wildlife and Nature
Natural History of the River
In the past, the Missouri River's floodplain had many different kinds of plants and animals. The variety of life generally increased as you went downstream, from the cold mountain headwaters to the warmer, wetter climate of Missouri. Today, the river's riparian zone (the area along its banks) mostly has cottonwoods, willows, and sycamores.
Because it carries so much sediment, the Missouri doesn't have many aquatic invertebrates (small animals without backbones). However, the basin is home to about 300 species of birds and 150 species of fish. Some of these, like the pallid sturgeon, are endangered. The river's habitats also support mammals like minks, river otters, beavers, muskrats, and raccoons.
The World Wide Fund For Nature divides the Missouri River watershed into three main natural regions: the Upper Missouri, Lower Missouri, and Central Prairie.
- The Upper Missouri region, in Montana, Wyoming, and the Dakotas, is mostly dry grasslands. It doesn't have a lot of different kinds of plants and animals because of the Ice Age glaciers.
- The Middle Missouri region, through Colorado, Nebraska, and parts of other states, gets more rain. It has temperate forests and grasslands, with more diverse plant and animal life.
- The Central Prairie region is on the lower part of the Missouri, in Missouri, Kansas, and other states. This region has the most different kinds of plants and animals, even though temperatures change a lot between seasons.
How People Have Changed the River's Ecology
Since river trade and industry began in the 1800s, human activity has greatly polluted the Missouri River and hurt its water quality. Most of the river's natural floodplain is gone. It has been replaced by irrigated farmland. Building on the floodplain has put more people and buildings at risk of floods.
Levees have been built along more than a third of the river. These keep floodwater in the channel, but they also make the water flow faster. This can increase floods in areas downstream. Fertilizer runoff from farms is a big problem, especially in Iowa and Missouri. This pollution also affects the Mississippi River. Low oxygen levels in rivers and the huge Gulf of Mexico dead zone are both caused by high nutrient levels from the Missouri and other rivers.
Straightening the lower Missouri River has made it narrower and deeper. This makes it harder for plants and animals that live along the river to survive. Many dams and bank projects have been built to turn 300,000 acres (1,214 km²) of the Missouri River floodplain into farmland. Controlling the river has reduced the amount of sediment it carries downstream. This has destroyed important habitats for fish, birds, and amphibians.
By the early 2000s, the populations of native species were declining. So, the U.S. Fish and Wildlife Service suggested restoring the river's habitats for endangered bird and fish species.
The USACE began working on projects to restore the ecosystem along the lower Missouri River. Since the shipping channel isn't used much, it's now possible to remove some of the levees, dikes, and wing dams. This would allow the river to naturally restore its banks. By 2001, about 87,000 acres (352 km²) of riverside floodplain were being restored.
Protected Areas Along the River
Several parts of the Missouri River have been added to the National Wild and Scenic Rivers System. This protects them for their natural beauty and recreational value. A total of 247 miles (398 km) of the river are protected.
Fun Things to Do on the Missouri
The six large reservoirs of the Missouri River Mainstem System offer many recreational activities. They have over 1,500 square miles (3,885 km²) of open water. More and more people are visiting these areas, from 10 million visitor-hours in the 1960s to over 60 million in 1990. The government has built boat ramps, campgrounds, and other facilities to encourage visitors. Recreation on these reservoirs brings in $85–100 million to the local economy each year.
The Lewis and Clark National Historic Trail is about 3,700 miles (5,955 km) long. It follows almost the entire Missouri River, from its mouth to its source. This trail traces the route of the Lewis and Clark Expedition. It passes through 11 U.S. states and about 100 historic sites.
Parts of the river itself are set aside for recreation and preservation. The Missouri National Recreational River includes parts of the Missouri downstream from Fort Randall and Gavins Point Dams. These sections are 98 miles (158 km) long and still have islands, sandbars, and other features that used to be common on the lower river. About forty-five steamboat wrecks are scattered along these parts of the river.
Downstream from Great Falls, Montana, about 149 miles (240 km) of the river flow through rugged canyons and badlands called the Missouri Breaks. This part of the river is a U.S. National Wild and Scenic River. It's part of the Upper Missouri Breaks National Monument, a 375,000-acre (1,518 km²) preserve. This area has steep cliffs, deep gorges, dry plains, and whitewater rapids. You can go boating, rafting, hiking, and watch wildlife there.
In north-central Montana, about 1,100,000 acres (4,452 km²) along the Missouri River, around Fort Peck Lake, make up the Charles M. Russell National Wildlife Refuge. This refuge has a natural northern Great Plains ecosystem that hasn't been changed much by people. You can hike and camp throughout the preserve.
Many U.S. national parks are partly in the Missouri River watershed. These include Glacier National Park, Rocky Mountain National Park, Yellowstone National Park, and Badlands National Park. Other rivers in the basin are also protected, like the Niobrara National Scenic River. The Missouri also flows through or past many National Historic Landmarks, such as Three Forks of the Missouri and Fort Benton, Montana.
See also
In Spanish: Río Misuri para niños
