mississippi Mississippi flows 3770 km from its source at Lake to its mouth in the Gulf of Mexico ranks as the second longest river in the United States after the Missouri River , it carries a greater volume of water than any other American river. This map, illustrating the three major rivers of the central United States, shows that the Missouri converges with the Mississippi near St. Louis, and the Ohio converges with the Mississippi in southern Illinois. The river is divided into the upper Mississippi, from its source south to the Ohio River , and the lower Mississippi, from the Ohio to its mouth near New Orleans, Louisiana. The Mississippi River runs through 10 states and was used to define portions of these states' borders. The middle of the riverbed at the time the borders were established was the line to define the borders between states. The river has since shifted, but the state borders of Wisconsin, Iowa, Illinois, Missouri, Kentucky, Arkansas, Tennessee, and Mississippi have not changed; they still follow the former bed of the Mississippi River as of their establishment. The name What Is A Watershed? What Is A Watershed?

A watershed describes an area of land that contains a common set of streams and rivers that all drain into a single larger body of water, such as a larger river, a lake or an ocean. For example, the Mississippi River watershed is an enormous watershed. All the tributaries to the Mississippi that collect rainwater eventually drain into the Mississippi, which eventually drains into the Gulf of Mexico. Rainwater that falls on more than half of the United States subsequently drains into the Mississippi. A watershed can cover a small or large land area. In the St. Louis vicinity, for instance, the Meramec River is a small river draining a relatively small amount of land. Small watersheds are usually part of larger watersheds. The Meramec River watershed, which is supplied by even smaller watersheds from dozens of streams, drains into the Mississippi River. All the streams flowing into small rivers, larger rivers, and eventually into the ocean, form an interconnecting network of waterways. Not only does water run into the streams and rivers from the surface of a watershed, but water also filters through the soil, and some of this water eventually drains into the same streams and rivers. These two processes, surface runoff and infiltration are important for a number of reasons.

A Stream in Washington State For one, they affect water quality. Think about it... The water that runs off the surface of the Earth picks up water pollution and deposits the pollution in streams and rivers as it drains the watershed. Along with many different types of pollution that are carried by surface runoff, soil also becomes a water pollutant as it is eroded from farm lands. Water that filters through the soil can also become contaminated with pollution that is left over from agricultural, industrial, commercial, and other types of human activity. The network of streams and rivers that drain our watershed and carry water pollution ultimately empty into larger bodies of water, such as lakes and oceans. As the larger rivers carrying water pollution from the land flow into lakes and oceans, all of the pollution that was in the rivers now is concentrated into these other bodies of water. The oceans of the world become the final resting place for tons of pollution. Through our watersheds, pollution is distributed far away from its original source. And oviously, polluted water affects water quality. About the Red River Watershed Basin rrwmi@lsus.edu About the Red River Watershed Basin The Red River Watershed Management Institute conducts research, education, and outreach in the Red River and its watershed.

What is a Watershed? A watershed is an area of land where all water flows or drains to the same place. This includes surface water and ground water. The Red River Watershed includes the Red River and all water that flows to it. Where does the Red River begin? The headwaters are the source of a stream/river. The Red River begins its total length of 1,360 miles in the Texas panhandle. The origins of the Red River are two forks (branches) in the Texas panhandle. The southern fork, Prairie Dog Town Fork, is formed in Randall County near Canyon, Texas. Prairie Dog Town Fork is formed from the confluence of Palo Duro Creek and Tierra Blanca Creek. The northern branch, North Fork, flows east entering Oklahoma. It then joins the southern branch at the Texas-Oklahoma border, northeast of Vernon, Texas. The Red River flows east, its south bank forming the border between Texas and Oklahoma and a portion of the border between Texas and Arkansas at the northeastern corner of Texas. The Red River flows into Arkansas and turns south at Fulton, Arkansas entering Louisiana near Ida.

In Louisiana the Red River forms the boundary between Caddo and Bossier parishes and flows southeast, through Red River, Natchitoches, Rapides, and Avoyelles parishes to join a partial outflow from the Mississippi River into the Atchafalaya River. Where does the Red River end? The Red River ends in Louisiana where it empties into the Mississippi River and the Atchafalaya. More specifically, the Red River ends as water from an outflow channel from the Mississippi River joins the Red River and flows into the Atchafalaya River near Simmesport, Louisiana. Water flowing from the Mississippi River into this outflow is regulated by the U.S. Army Corps of Engineers at the Old River Control Structure. The water from the Atchafalaya River flows into the Gulf of Mexico. Sediment deposited forms the Atchafalaya Delta. What are Floodplains? A floodplain is the land near a stream that is inundated during floods. A floodplain is made by stream erosion and deposition. Floodplains occur when the water flowing in a stream/river is too great to be contained in its banks.

The flood water exceeds the carrying capacity of the river and the water flows over the banks into the floodplain, the low lying area adjacent to the stream/river. What are Oxbow Lakes? An oxbow lake is a crescent shaped lake that is formed when a meander of a river is cutoff to form a lake. An oxbow lake is created over time by erosion and deposition of soil as a river changes course. As the river meanders the water flows at different speeds across its width. The water traveling against the inside loop of a bend in the river travels slow, causing deposition of sediments. The water in outside edge of the loop travels faster causing erosion of the river sediment. Over time the loop of the meander will be cut off from the main path of the river as the river takes the easiest route and continues in a straight path and silt fills in the old extensions of the meander forming the U-shaped oxbow lake. Sometimes more than one meander is involved and the shape of the oxbow lake is more serpentine or even "E" shaped, like the oxbow lake at the Red River Education and Research Park (Old River Lake).

Â River Basins | New Georgia Encyclopedia Blackwater River Basins Georgia's natural resources include fourteen river basins, which support a rich diversity of native fish and mussel species. A river basin consists of the entire geographic area (hillside, valley, plain) from which water flows into the primary river, which is made up of an intricate network of smaller rivers and streams. Rain falling within a river basin, or watershed, runs downhill until it reaches a stream. Small streams join other streams and flow into a river, and eventually that river flows into the sea. The fourteen river basins of Georgia are the Altamaha, Chattahoochee, Coosa, Flint, Ochlockonee, Ocmulgee, Oconee, Ogeechee, Satilla, Savannah, Suwanee, St. Marys, Tallapoosa, and Tennessee. The Savannah River , which begins at the confluence of the Seneca and Tugaloo rivers in the northeast part of the state, forms the border between Georgia and South Carolina. Georgia River Basins It empties into the Atlantic Ocean near Savannah .

The Tennessee River, part of the northwestern Coosa and Tallapoosa river basins, flows northward and enters the Mississippi River via the Ohio River. Both the Coosa River, which begins in the Blue Ridge Mountains , and the Tallapoosa River, which begins in the Piedmont , flow into the Mobile River basin in Alabama. Farther south, the Chattahoochee and Flint river basins include the highly urbanized Atlanta metropolitan area; these rivers eventually merge and Ogeechee River empty into the Gulf of Mexico. In central Georgia, the Oconee and Ocmulgee rivers merge to form the Altamaha River , which flows to the Atlantic Ocean. Three of the five blackwater rivers in Georgia's coastal plain , the Ogeechee, Satilla, and St. Marys rivers, drain to the Atlantic Ocean, while the remaining two, the Suwanee and Ochlockonee, are Gulf Coast drainages. Rivers provide not only habitat for fish, aquatic invertebrates, amphibians , and terrestrial fauna but also recreational opportunities, water supplies for communities, irrigation for agriculture , and a means of transportation.

The river basins in Georgia are nonrenewable public resources critical to the integrity of natural environments and public health. To that end several organizations are committed to the protection and conservation of Georgia's rivers, including American Rivers, Georgia Adopt-A-Stream, Georgia Canoeing Association, Georgia River Network, Georgia Wildlife Federation , National Wildlife Federation, Nature Conservancy, and Trout Unlimited. Georgia has a vast diversity of surface and groundwater resources. The Environmental Protection Agency estimates that Georgia has 44,056 miles of perennial streams, 23,906 miles of intermittent streams, Ogeechee River Watershed and 603 miles of ditches and canals . Georgia has 4.8 million acres of wetlands, 425,382 acres of public lakes and reservoirs , 854 square miles of estuaries , and 100 miles of coastline. In the forty-eight contiguous states, there are only forty-two free-flowing rivers greater than 200 kilometers in length, and Georgia contains five such rivers: the Flint , Ogeechee, Satilla, St. Marys, and Suwannee.

Populations in the northern part of Georgia rely heavily on surface water supplies, and populations south of the fall line rely mainly on groundwater supplies. Both surface and groundwater sources are highly susceptible to contamination from runoff (known as nonpoint source pollution) from leaking landfills and underground storage tanks, as well as from industrial processes. Some of the critical issues for the state's long-term supply of groundwater and surface water supplies include saltwater intrusion in the upper Floridan aquifer of coastal Georgia, the equitable allocation of water with Alabama and Florida, and the growing demand on limited water resources in metropolitan Atlanta. Two additional issues facing southwest Georgia are the depletion of the Clayton aquifer and the reductions in flow through the Flint River basin resulting from surface and groundwater withdrawals for irrigation. Savannah River Basin Savannah River Savannah River basin includes portions of North Carolina, South Carolina, and Georgia and flows through the Blue Ridge Mountains, Piedmont, and Coastal Plain of Georgia. The Savannah River forms the boundary between South Carolina and Georgia and begins at Lake Hartwell, in Hart County , at the confluence of the Seneca and Tugaloo rivers. From this point it flows southeast to Savannah, where it empties into the Atlantic Ocean.

Above the junction of the Seneca and Tugaloo rivers, the major headwater streams of the Seneca River are the Keowee River and Twelve Mile Creek. The Tugaloo River is formed by the union of the Tallulah and Chattooga rivers. These headwater streams originate on the southern slopes of the Blue Ridge Mountains in North Carolina and Georgia. Flow, Savannah River Watershed sediment load, and the flood plain of the Savannah River have been modified by eleven large dams above the fall line, which impound more than 180,000 acres of water. Below the fall line, dredging and channelization have altered the historical legacy of the Savannah. As a result the Savannah lacks the vast vegetated flood plains in the freshwater tidal zone that are characteristic of such other Georgia estuaries as the Altamaha River. However, the Savannah does have extensive developments of more saline intertidal vegetational zones near the sea. The Savannah National Wildlife Refuge seeks to protect, preserve, and educate the public about the diversity and fragility of this river system. In the late 1990s the federal Environmental Protection Agency (EPA) outlined significant man-made and natural threats to the Savannah River system.

For example, the construction of dams to provide hydroelectric power and to reserve surface water to sustain municipal water requirements leads to releases of cold water with low dissolved oxygen, which can result in massive fish Tugaloo Dam mortalities below the dam. Development in the watershed can lead to increased urban/storm water runoff, nonpoint source releases into the watershed, and the loss of critical wetland habitats. Discharges and releases from the Savannah River Site, a nuclear materials processing center in South Carolina that was listed as an EPA Superfund site in 1989, also threaten the health of the Savannah. As the drought in Georgia continues, the water tables continue to drop farther beneath the surface. As the water tables drop, concerns increase over saltwater intrusion into groundwater supplies and the potential for an interaction with surface water supplies. Coosa, Tallapoosa, and Tennessee River Basins The Tallapoosa River Coosa and Tallapoosa River basins originate in north Georgia and continue across the border into Alabama. The Tennessee River basin includes portions of Alabama, Georgia, Kentucky, Mississippi, North Carolina, Tennessee, and Virginia. The Tallapoosa River originates west of Atlanta, in Paulding County .

The Tallapoosa River basin occupies 4,680 square miles, of which 720 square miles (15 percent) lie in Georgia and 3,960 square miles (85 percent) lie in Alabama. The Tallapoosa supports cold- and warm-water fisheries as well as a rich diversity of species unique to this river. Species important to anglers include largemouth, spotted, and redeye bass; rainbow trout; black crappie; and channel catfish. The Tallapoosa is a free-flowing river in Georgia with no major impoundments until it reaches the Harris Reservoir in Alabama. The Coosa River Coosa River, formed by the convergence of the Etowah and Oostanaula rivers in downtown Rome , is the major eastern tributary of the Mobile River basin and empties into the Gulf of Mexico in southwest Alabama. The Coosa River is a significant striper fishery with one of the few naturally reproducing populations of striped bass in the state and is home to more than 147 species of fish. The river also has the largest diversity worldwide of freshwater snails and mussels, despite the documented disappearance of numerous molluscan species .

For example, it is estimated that 35 of the 50 freshwater mussel species that once probably inhabited the Coosa River basin have been extirpated; several of these species are now considered extinct. According to estimates by the Nature Conservancy, the Etowah River, which flows into the Coosa, has more imperiled species than any other river system of its size in the southeastern United States. The Upper Tennessee River Basin Tennessee River originates in the Appalachian Mountains and eventually joins the Ohio River. The largest tributary of the Ohio, the Tennessee is most notable for its abundance and diversity of freshwater fishes. Recognized as one of the most diverse rivers in North America, the Tennessee River supports about 240 fish species. The Coosa, Tallapoosa, and Tennessee rivers are home to many threatened and endangered aquatic species. Two of the endangered species in these river basins are the Conasauga logperch, Percina jenkinsi, and the amber darter, Percina antesella. These species were once found throughout the Coosa, Tallapoosa, and Tennessee river basins and have been federally listed as Conasauga Logperch endangered since 1985.

The Conasauga logperch grows to approximately six inches in length and is characterized by many tigerlike vertical stripes over a yellow background and a piglike conical snout. Like other logperches, the Conasauga logperch feeds by flipping stones over with its snout and consuming the aquatic invertebrates living beneath. The amber darter is a short, slender-bodied fish that is generally fewer than two-and-a-half inches in length. The fish's upper body is golden brown with dark saddle-like markings, and its belly is a yellow-to-cream color. The throats of breeding males are blue in color. The amber darter feeds primarily on snails and insects. Chattahoochee and Flint River Basins The Flint River Chattahoochee and Flint rivers are part of a larger Apalachicola-Chattahoochee-Flint (ACF) river basin, which flows through the states of Georgia, Alabama, and Florida. The Chattahoochee River drains an area of 8,770 square miles and is the most heavily used water resource in Georgia.

Its headwaters begin at the southern edge of the Blue Ridge Mountains in Union County , at an altitude above 3,000 feet, and flow 430 miles to the Chattahoochee's confluence with the Flint River in southwest Georgia at Lake Seminole, in Seminole County . The Flint River is approximately 350 miles long and drains an area of 8,460 square miles. Most of the larger tributaries in the ACF river basin are located in the lower reaches of the Flint River basin. The headwaters of the Chattahoochee and Flint rivers occur north of the fall line in the Blue Ridge and Piedmont respectively. Water supplies in the headwater region derive primarily from surface waters. South of the fall line are the Providence aquifers and upper Cretaceous strata. The Providence aquifer system is the deepest of the principal aquifers in southern Georgia and consists of sand and gravel separated by clay and silt confining beds. The lower reaches of both rivers are part of the Floridan aquifer system, a karst limestone aquifer that is susceptible to contamination. This aquifer is one of the most productive worldwide.

The hydrology connecting the Floridan aquifer and the Flint River results in groundwater discharge contributing to baseflow more in the Flint River than in the Chattahoochee River. Groundwater flow into the Chattahoochee River is one-fifth of that discharging into the Flint River. Environmental Concerns Chattahoochee River of the most endangered rivers in the nation, the Chattahoochee River provides valuable wildlife habitat for migratory birds , mammals (including deer, beaver, and otter), and reptiles and amphibians . There are four federally endangered and two federally threatened mussel species found in the Chattahoochee and Flint river basins. The four endangered mussels—the fat threeridge (Amblema neislerii), shinyrayed pocketbook (Lampsilis subangulata), Gulf moccasinshell (Medionidus penicillatus), and oval pigtoe (Pleurobema pyriforme)— have been federally listed as endangered since 1997. The two threatened mussels are the chipola slabshell (Elliptio chipolaensis) and purple bankclimber (Elliptoideus sloatianus).

All six mussel species prefer main-channel or large-stream sandy habitats with slow to moderate currents. Six Amber Darter percent of the surface waters sampled in the upper Flint River and 19 percent of those sampled in the lower Flint River are categorized as impaired by the Environmental Protection Agency. Nonpoint sources and urban/storm water runoff are the primary contributors to pollution in the Flint. The highest impairment of surface waters in the Chattahoochee River occurs in the upper and middle reaches of the river, which flow through Atlanta. The upper Chattahoochee is ranked in the top 10 percent of the most polluted watersheds in the state of Georgia and in the top 20 percent in the nation. Significant contributions to this pollution include urban/storm water runoff, nonpoint and municipal point sources, and combined sewer outflows. Impoundments West Point Lake U.S. Army Corps of Engineers has constructed sixteen mainstem dams, which create large impoundments for flood control, water supply, power, and commercial navigation, in the ACF river basin. Thirteen of these dams are on the Chattahoochee River. Along most of the river's length, hydroelectric plants release water to produce hydropower and to control the river's flow.

In the early 1800s dam construction in the basin began on the Chattahoochee River above the fall line at Columbus to take advantage of natural elevation gradients for power production. During low flow periods, stored water is used to supplement the discharge of the river. There have been marked decreases in the frequency of high and low flows since the start of operation of Buford Dam in 1956, and river flows fluctuate daily below the reservoirs along the Chattahoochee River. Lake Lanier provides 65 percent of the water storage to regulate flows, yet it drains only 5 percent of the ACF river basin. Four large reservoirs along the Chattahoochee River include Lake Lanier (38,000 acres in area and 540 miles of shoreline), West Point Lake (25,900 acres in area and 525 miles of shoreline), Lake Walter F. George (45,180 acres in area and 640 miles of shoreline), and Seminole (37,500 acres in area and 500 miles of shoreline).

Two hydropower dams located on the Flint River impound run-of-the-river reservoirs (which means that the amount of water flowing through the dam is the same amount flowing into the reservoir from the river upstream) and do not appreciably influence the monthly flow of the Flint River. The dams do alter the daily flow regime, however. The Flint River lacks impoundments for more than 200 river miles. Ocmulgee, Oconee, and Altamaha River Basins The Oconee River headwaters of the Oconee and Ocmulgee rivers originate in the foothills of the Appalachians and meet to form the Altamaha River in the Upper Coastal Plain . Atlanta and Macon are major metropolitan areas along the Ocmulgee River. Along the Oconee River, Athens is located in the headwater region, and Milledgeville and Dublin are located in the middle and southern reaches of the river. Farther downstream of the confluence between the Ocmulgee and Oconee rivers, the Ohoopee River, a blackwater tributary, joins the Altamaha.

A major continental divide occurring between the Ocmulgee and Flint rivers causes the Altamaha River basin to drain into the Atlantic Ocean. The Altamaha River basin is the largest watershed in the state of Georgia and the third largest in the United States draining into the Atlantic Ocean. Three distinct groundwater aquifers influence the Altamaha River basin. In the northern headwaters of the Ocmulgee and Oconee rivers, crystalline-rock aquifers dominate. In the lower reaches of these rivers, cretaceous aquifer systems lie beneath the surface. The Altamaha River is part of the large Floridan aquifer system. Groundwater aquifers that occur near the fall line are exposed Altamaha River Watershed or close to the surface. South of the fall line, which includes the Altamaha River, the majority of domestic water supplies comes from groundwater sources. A total of 137 river miles marks the distance between the convergence of the Oconee and Ocmulgee rivers and the entry of the Altamaha into the Atlantic Ocean near Darien . The tidal estuary at the mouth of the Altamaha functions as a linkage between the freshwater habitats of the river basin with the saltwater system of the Atlantic Ocean.

During the 1800s the Altamaha River was a major route for shipping to the Georgia coast. Agriculture dominates the landscape of the Ocmulgee, Oconee, and Altamaha basins and has a direct impact on the health of the watershed. The Ocmulgee River officially begins southeast of Atlanta, where the Yellow, Alcovy, and South rivers converge at Lake Jackson. Downstream the Ocmulgee's watershed is dominated by agriculture and forested areas. The Oconee River headwaters arise in a highly forested region, but the presence of agriculture increases as the Oconee flows southeastward toward the Altamaha River. The ninety-mile coastal flood plain of the Altamaha River is covered with dense timber and underbrush. The upper reaches of both the Oconee and Ocmulgee watersheds have been particularly affected by a combination of pollutants from urban runoff, storm sewers, municipal point sources, and combined sewer outflows. In the Altamaha River watershed, nonpoint source pollution contributes Altamaha River to organic enrichment, metals contamination, and fish consumption advisories in the Altamaha and its tidal estuarine system.

The National Dam Inventory documents 276 dams in the upper Oconee River watershed, while a detailed scale analysis found more than 5,400 impoundments in the watershed. These figures demonstrate that the majority of the reservoirs in this watershed are unaccounted for and that their environmental impacts can be underestimated. Two large dams (greater than twenty-five-feet high) were built along the mainstem of the Oconee River, creating Lake Sinclair and Lake Oconee. Neither the Ocmulgee River nor the Altamaha River has large dams built along its mainstem. More than 100 rare and endangered aquatic species are found in the Altamaha. The watershed provides habitats for nesting and breeding migratory birds as well as for common game species. In 1991 the Nature Conservancy initiated an ecological survey to assess the biological resources and potential threats to the integrity of freshwater species diversity in the Altamaha River. This fragile watershed sustains several imperiled pearly mussel species, some of which are found nowhere else in the world. Blackwater River Basins St.

Marys River Watershed rivers in Georgia's Coastal Plain form a collective river basin: the Ochlockonee, Ogeechee, Satilla, St. Marys, and Suwannee. The Ogeechee, which begins in Greene County ; the Satilla, which begins in Ben Hill County ; and the St. Marys, which begins in Charlton County , are Atlantic Coast drainages. The Suwannee, which begins in Dooly County , and the Ochlockonee, which begins in Worth County , drain to the Gulf of Mexico. The St. Marys and Suwannee rivers also drain portions of the Okefenokee Swamp , and the St. Marys River forms the boundary between Georgia and Florida. Each of these rivers drains sandy soils that lack the ability to retain dissolved organic matter leached from terrestrial vegetation. For that reason their water is tea-colored, and they are referred to as blackwater rivers. Even though there are high concentrations of dissolved organic matter in the blackwater river basin, the suspended sediment levels are low. Extremely low concentrations of dissolved oxygen occur in blackwater rivers during the warmer months of the year.

Ogeechee River Tributary These rivers have very little change in elevation per unit river length and extensive floodplains. The pH of the Ogeechee River is near 7.0 since there is a large input of carbonate-rich water from Magnolia Springs. The Satilla River has a much lower pH (around 5.0) and lies entirely within the Coastal Plain. Development and industrial or residential pollution is very low, and there is relatively little agricultural runoff into the river basin. Cypress and black gum forests fill the floodplain swamps that border the length of the Satilla River. Historically, large amounts of woody debris and snags created an intricate patchwork of blackwater rivers and riparian zones. These stream bottoms consist primarily of constantly shifting sand, and woody debris and snags provide a stable habitat for insects and thus are vital to the secondary production of aquatic insects. Snagging operations at the turn of the twentieth century changed Satilla River Watershed the rivers. For example, wood-removal operations were more intense in the Satilla River than in the Ogeechee River; hence less woody debris remains in the main channel of the Satilla.

Flooding plays an important role in the exchange between the surrounding watershed and the main channel of each blackwater river. The highest concentrations of total organic carbon occur during these flooding periods, and the lowest concentrations are measured during low flow periods. This exchange between the mainstem and the floodplain occurs because of the lack of impoundments and the low gradient of these rivers. You Might Also Like river - National Geographic Society river The Jinsha is nicknamed "the River of Golden Sands." Photograph by Xi Luo, MyShot Germ-Killing Ganges Hindus have always believed that the water of the Ganges River has purifying powers. Although millions of people bathe in the river regularly, it does not usually spread cholera, typhoid, or other water-borne diseases. Scientists have found that unique bacteriophagesviruses that destroy bacteriakill germs in the water of the Ganges. In addition, the Ganges holds up to 25 times more dissolved oxygen than any other river in the world. The oxygen helps prevent putrefaction (rotting) of organic matter in the river. Scientists do not know why the river retains so much oxygen. Mythical Rivers The ancient Greeks believed that five rivers encircled Hades, the underworld.

These rivers are Styx (hate), Phlegethon (fire), Acheron (sorrow), Cocytus (lamentation or sadness), and Lethe (forgetting). The Greeks believed that dead souls had to cross the River Acheron, a branch of the Styx, to reach the underworld. They crossed on a ferry piloted by Charon, the ferryman of Hades. Flip-Flopping Flow The Amazon River used to flow in the opposite direction. Today, the river flows from the mountains of Peru in the west to the Atlantic Ocean in the east. But millions of years ago, it actually flowed from east to west, emptying into the Pacific Ocean. The flow flipped when the Andes mountains started growing at the end of the Cretaceous period (around 65 million years ago). A river is a large, natural stream of flowing water. Rivers are found on every continent and on nearly every kind of land. Some flow all year round. Others flow seasonally or during wet years. A river may be only kilometers long, or it may span much of a continent. The longest rivers in the world are the Nile in Africa and the Amazon in South America. Both rivers flow through many countries.

For centuries, scientists have debated which river is longer. Measuring a river is difficult because it is hard to pinpoint its exact beginning and end. Also, the length of rivers can change as they meander , are dam med, or their deltas grow and recede . The Amazon is estimated to be between 6,259 kilometers (3,903 miles) and 6,800 kilometers (4,225 miles) long. The Nile is estimated to be between 5,499 kilometers (3,437 miles) and 6,690 kilometers (4,180 miles) long. There is no debate, however, that the Amazon carries more water than any other river on Earth. Approximately one-fifth of all the freshwater entering the oceans comes from the Amazon. Rivers are important for many reasons. One of the most important things they do is carry large quantities of water from the land to the ocean. There, seawater constantly evaporate s. The resulting water vapor forms clouds. Cloud s carry moisture over land and release it as precipitation. This freshwater feeds rivers and smaller streams. The movement of water between land, ocean, and air is called the water cycle .

The water cycle constantly replenish es Earth’s supply of freshwater, which is essential for almost all living things. Anatomy of a River No two rivers are exactly alike. Yet all rivers have certain features in common and go through similar stages as they age. The beginning of a river is called its source or headwater s. The source may be a melting glacier , such as the Gangotri Glacier, the source of the Ganges River in Asia. The source could be melting snow, such as the snows of the Andes, which feed the Amazon River. A river’s source could be a lake with an outflowing stream, such as Lake Itasca in the U.S. state of Minnesota, the source of the Mississippi River. A spring bubbling out of the ground can also be the headwaters of a river. The source of the Danube River is a spring in the Black Forest of Germany. From its source, a river flows downhill as a small stream. Precipitation and groundwater add to the river’s flow. It is also fed by other streams, called tributaries. For instance, the Amazon River receives water from more than 1,000 tributaries.

Together, a river and its tributaries make up a river system . A river system is also called a drainage basin or watershed. A river’s watershed includes the river, all its tributaries, and any groundwater resources in the area. The end of a river is its mouth . Here, the river empties into another body of water—a larger river, a lake, or the ocean. Many of the largest rivers empty into the ocean. The flowing water of a river has great power to carve and shape the landscape. Many landforms, like the Grand Canyon in the U.S. state of Arizona, were sculpted by rivers over time. This process is called weathering or erosion . The energy of flowing river water comes from the force of gravity, which pulls the water downward. The steeper the slope of a river, the faster the river moves and the more energy it has. The movement of water in a river is called a current . The current is usually strongest near the river’s source. Storms can also increase the current. A swift current can move even large boulder s. These break apart, and the pieces that are carried in the moving water scrape and dig into the river bottom, or bed.

Little by little, a river tears away rocks and soil along its bed, and carries them downstream. The river carves a narrow, V-shaped valley. Rapids and waterfall s are common to rivers, particularly near their sources. Eventually, the river flows to lower land. As the slope of its course flattens, the river cuts less deeply into its bed. Instead, it begins to wind from side to side in looping bends called meanders. This action widens the river valley. At the same time, the river begins to leave behind some of the rocks, sand, and other solid material it collected upstream . This material is called sediment . Once the sediment is deposited, it is called alluvium . Alluvium may contain a great deal of eroded topsoil from upstream and from the banks of its meanders. Because of this, a river deposits very fertile soil on its flood plain . A flood plain is the area next to the river that is subject to flooding. The deepest part of a river bed is called a channel . The channel is usually located in the middle of a river. Here, the current is often strong. In large rivers, ships travel in channels.

Engineers may dredge , or dig, deeper channels so more water can flow through the river or the river can transport larger ships. Near the end of its journey, the river slows and may appear to move sluggishly . It has less energy to cut into the land, and it can no longer carry a heavy load of sediment. Where the river meets the ocean or a lake, it may deposit so much sediment that new land, a delta , is formed. Not all rivers have deltas. The Amazon does not have a true delta, for instance. The strength of the tide s and currents of the Atlantic Ocean prevent the build-up of sediment. Deltas almost always have fertile soil. The Nile Delta and the Ganges Delta are the chief agricultural areas for Egypt and Bangladesh, for instance. Rivers Through History Rivers have always been important to people. In prehistoric times, people settled along the banks of rivers, where they found fish to eat and water for drinking, cooking, and bathing. Later, people learned that the fertile soil along rivers is good for growing crop s.

The world’s first great civilization s arose in the fertile flood plains of the Nile in Egypt, the Indus in southern Asia, the Tigris and the Euphrates in the Middle East, and the Huang (Yellow) in China. Centuries later, rivers provided routes for trade , exploration , and settlement. The Volga River in Eastern Europe allowed Scandinavia n and Russian cultures, near the source of the river, to trade goods and ideas with Persia n cultures, near the mouth of the Volga in southern Europe. The Hudson River in the U.S. state of New York is named after English explorer Henry Hudson , who used the river to explore what was then the New World . When towns and industries developed, the rushing water of rivers supplied power to operate machinery . Hundreds of factories operated mill s powered by the Thames in England, the Mississippi in the United States, and the Ruhr in Germany. Rivers remain important today. If you look at a world map, you will see that many well-known cities are on rivers. Great river cities include New York City, New York; Buenos Aires, Argentina; London, England; Cairo, Egypt; Kolkata, India; and Shanghai, China.

In fact, rivers are usually the oldest parts of cities. Paris, France, for instance, was named after the Iron Age people known as the Parisii , who lived on the islands and banks of the Seine River, which flows through the city. Rivers continue to provide transportation route s, water for drinking and for irrigating farmland, and power for homes and industries. Rivers of Europe The longest river in Europe is the Volga. It flows approximately 3,685 kilometers (2,290 miles) across Russia and empties into the Caspian Sea. The Volga has been used for centuries to transport timber from northern forests, grain from farms along its valley, and manufactured goods. The river is also known for its sturgeon , a type of large fish whose eggs are used to make a famous delicacy —Russian caviar. The Thames, in England, is one of Europe’s most historic rivers. Along its banks stands the city of London, a bustling urban area for more than a thousand years. By 100 CE, London had already become an important Roman settlement and trading post . Because of its location on the river and near the seacoast, London became England’s principal city and trade center.

Europe’s busiest river is the Rhine, which runs from the Alps in Switzerland, through Germany and the Netherlands, and empties into the North Sea. It flows through many industrial and farming regions and carries barge s laden with farm products, coal , iron ore , and a variety of manufactured goods. Rivers of Asia Asia’s longest and most important river is the Yangtze, in China. It flows from the Dangla Mountains, between Tibet and China’s Qinghai province. It empties in the East China Sea 6,300 kilometers (3,915 miles) later. The Yangtze is a highway for trade through the world’s most populous country. The Yangtze is also an agricultural river. Its valley is a major rice-growing region, and its water is used to irrigate fields. Many Chinese live on the river in houseboat s or sailboat s called junk s. The Yangtze River is the home of the world’s most powerful hydroelectric power plant, the Three Gorges Dam . Eventually, the plant will be able to constantly produce 22,500 megawatts of power. China’s rural population will have access to affordable electricity for homes, businesses, schools, and hospitals.

Creating the Three Gorges Dam was one of the largest engineering feat s in history. Engineers dammed the Yangtze, creating a 39.3-cubic-kilometer (31.9 million acre-foot) reservoir , or artificial lake. The Ganges is the greatest river on Asia's Indian subcontinent . It is sacred to the millions of followers of the Hindu religion. For thousands of years, Hindus have worshipped the river as a goddess, Ganga Ma (Mother Ganges). Hindus believe the river’s water purifies the soul and heals the body. Millions of people use the Ganges every day for bathing, drinking, and industry. The historic Tigris and Euphrates river system flows from Turkey through Syria and Iraq and into the Persian Gulf. The rivers lie in an area called the Fertile Crescent . The region between the two rivers, known as Mesopotamia , is the so-called “cradle of civilization.” The earliest evidence of civilization and agriculture —farming and domestication of animals—appears in the Fertile Crescent. Rivers of North America In North America, rivers served as highways for native tribes and, later, for European explorers.

French explorers began traveling the St. Lawrence and other rivers of Canada in the 1500s. They found an abundance of fish and other wildlife, and they encountered Native American tribes who hunted beaver. The explorers took beaver pelt s back to Europe, where they were used to make fashionable hats. Soon, hunters explored and traveled networks of rivers in North America in search of beaver pelts. The establishment of trading posts along the rivers later opened the way for permanent European settlers. The St. Lawrence River is still a major waterway . The river, which empties into the Atlantic, is linked to the Great Lakes by the St. Lawrence Seaway —a series of canal s, lock s, dams, and lakes. The St. Lawrence Seaway allows oceangoing ships to enter the interior of the continent. The Mississippi is the chief river of North America. It flows approximately 3,766 kilometers (2,340 miles) through the heart of the United States, from its source in Minnesota to its delta in Louisiana and the Gulf of Mexico. Spanish and French explorers first traveled the Mississippi in the 1500s and 1600s.

In 1803, the United States bought almost the entire Mississippi River Valley from France as part of the Louisiana Purchase . After that, the Mississippi was widely traveled by traders and settlers on rafts, boats, and barges. With the introduction of the steamboat , a new, industrial, era began on the Mississippi. Paddle wheeler s carried trade goods up and down the river. Soon, workboats were joined by cruise ship s and other luxurious passenger vessels. Writer Mark Twain , who was once a steamboat pilot on the river, described this era in his book Life on the Mississippi. Over time, the Mississippi increased in importance as a trade route. Today, it carries cargo ships and barges in lines that may extend for more than a kilometer. Large quantities of petroleum , coal, and other bulky goods are conveyed on the river by massive barges pushed by powerful towboat s. North America’s Colorado River is famous for forming the Grand Canyon in Arizona. For millions of years, the river has cut its way through layers of rock to carve the canyon. Long ago, the river flowed through a flat plain. Then the Earth’s crust began to rise, lifting the land. The river began cutting into the land.

The Grand Canyon is now about one and a half kilometers (one mile) deep at its deepest point, and 29 kilometers (18 miles) wide at its widest. Rivers of South America The strength of the Amazon River in South America dwarf s all other rivers on the planet. The amount of water flowing through the Amazon is greater than the amount carried by the Mississippi, the Yangtze, and the Nile combined. The Amazon begins as an icy stream high in the Andes mountains of Peru. It flows through Brazil and empties into the Atlantic Ocean. The Amazon and its tributaries drain a basin that covers an area equal to three-fourths of the contiguous United States. The first Europeans to see the Amazon were Spanish explorers, who traveled it in the 1500s. They encountered a group of natives who all appeared to be women, or so the story goes. The explorers called the people Amazon s, after female warriors described in Greek myth ology. The name Amazon was later given to the river. For much of its course, the Amazon flows through the world’s largest tropical rain forest .

The region has abundant and unusual wildlife, including flesh-eating fish called piranha s; huge fish called pirarucu , which can weigh more than 125 kilograms (275 pounds); and giant snakes called anaconda s. Some Amazon tribes remain independent of Western culture. The Tagaeri people, for instance, continue to live a nomad ic life based around the Amazon and its tributaries in the rain forest of Ecuador. Because of the demand for timber from the rain forest, the land of the indigenous people of the Amazon is shrinking. Today, there are fewer than 100 Tagaeri living in the rain forest. Rivers provide energy to many South American communities. The Itaipú Dam crosses the Paraná River on the Brazil-Paraguay border. Construction of the dam required the labor of thousands of workers and cost more than $12 billion. The dam’s power plant can regularly produce some 12,600 megawatts of electricity. The huge reservoir formed by the dam supplies water for drinking and for irrigation. Rivers of Africa Africa’s two largest rivers are the Nile and the Congo.

One tributary of the Nile, the White Nile , flows from tiny streams in the mountains of Burundi through Lake Victoria, Africa’s largest lake. The other tributary, the Blue Nile , begins in Lake Tana, Ethiopia. The two join at Khartoum, Sudan. The Nile then flows through the Sahara Desert in Sudan and Egypt, and empties into the Mediterranean Sea. Because the area where the tributaries meet is close to the two sources of the Nile, the area is called the Upper Nile , even though it is farther south geographically. The Lower Nile runs through Egypt. One of the earliest civilizations in the world developed along the Lower Nile. Ancient Egyptian civilization arose about 5,000 years ago. It was directly related to the Nile and its annual flooding. Each year, the river overflowed, spreading rich sediment across its broad flood plain. This made the land extremely fertile. Egyptian farmers were able to grow plentiful crops. In fact, ancient Egyptians called their land Kemet, which means “Black Land,” because of the rich, black soil deposited by the river. Egyptians also used the Nile as a major transportation route to both the Mediterranean and the African interior.

The Pschent , or double crown worn by Egyptian monarch s, combined symbolism from both the Upper Nile and Lower Nile. A tall, white crown shaped like a bowling pin represented the lands of the Upper Nile. This crown was combined with a pointy red crown that had a curly wire protruding from the front. The red color symbolized the red soils of Lower Egypt, while the curly wire represented a honeybee . When putting on the Pschent, an Egyptian ruler assumed leadership for the entire Nile. The Nile provided enterprising Egyptians with material to form a powerful civilization. From papyrus , a tall reed that grew in the river, Egyptians made a sort of paper, as well as rope, cloth, and baskets. Egyptians also built great cities, temples, and monuments along the river, including tombs for their monarchs, or pharaoh s. Many of these ancient monuments are still standing. The Congo River flows across the middle of Africa, through a huge equatorial rain forest, before emptying in the Atlantic Ocean. The Congo is second only to the Amazon in terms of water flow. It is the deepest river in the world, with measured depths of more than 230 meters (750 feet).

Huge urban areas, including the capital cities of Brazzaville, Republic of Congo, and Kinshasa, Democratic Republic of Congo, sit on the banks of the river. In the Democratic Republic of Congo, the river is the principal highway for transporting goods such as cotton, coffee, and sugar. Boats traveling the river range from dugout canoe s to large freighter s. The river also supplies an abundance of fish to central Africa. Fishermen use baskets and nets hung from high poles across rushing falls and rapids to catch fish. They also use more traditional nets operated from either onshore or on boats. Rivers of Australia Much of Australia is arid , but rivers still run through it. Australia’s principal rivers are the Murray and the Darling, both in the southeastern part of the continent. The Murray flows some 2,590 kilometers (1,610 miles) from the Snowy Mountains to a lagoon on the Indian Ocean. Near the town of Wentworth, the Murray is joined by the Darling, a 2,739-kilometer (1,702-mile) river that flows from the highlands of the eastern coast. Indigenous Australians placed great importance on the Murray River.

The Murray valley had the greatest population density on the continent before the arrival of Europeans in the 1600s. By the mid-1800s, European farmers had settled along both rivers and some of their tributaries. Most Australian farmers raised sheep and cattle. Riverboats began plying the waters, and towns grew up along the banks. Much of Australia’s farmland still lies within the Murray-Darling basin, where river water irrigates some 1.2 million hectares (3 million acres). The region is the chief supplier of the country’s agricultural export s—wool, beef, wheat, and oranges. Polluted Rivers For centuries, people have depended on rivers for many things. Rivers have provided waterways for shipping, convenient construction sites for cities, and fertile land for farming. Such extensive use of rivers has contributed to their pollution . River pollution has come from directly dumping garbage and sewage , disposal of toxic waste s from factories, and agricultural runoff containing fertilizer s and pesticide s. By the 1960s, many of the world’s rivers were so polluted that fish and other wildlife could no longer survive in them. Their waters became unsafe for drinking, swimming, and other uses.

One of the most famous examples of a polluted river was the Cuyahoga. The Cuyahoga is a busy river in the U.S. state of Ohio that empties into Lake Erie. It is a major highway for goods and services from the Midwest to the Great Lakes. In 1969, the oily pollution in the Cuyahoga was so great that the river actually caught fire—something it had done more than a dozen times in the 19th and 20th centuries. Since the 1969 fire, stricter laws have helped clean up polluted rivers. The laws have restrict ed the substances factories can dump into rivers, limited the amount of agricultural runoff, banned toxic pesticides such as DDT , and required treatment of sewage. Although the situation in some parts of the world has improved, serious problems remain. The Citarum River in Indonesia, for instance, is often cited as the most polluted river in the world. Textile factories near the Citarum dump toxic wastes into the river. The garbage floating on top of the river is so thick that water is invisible. Even after communities have limited river pollution, toxic chemicals may remain. Many pollutants take years to dissolve.

The pollutants also build up in the river’s wildlife. Toxic chemicals may cling to algae , which are eaten by insects or fish, which are then eaten by larger fish or people. At each stage of the river’s food web , the amount of the toxic chemical increases. In parts of North America and Europe, there is also the severe problem of acid rain . Acid rain develops when emission s from factories and vehicles mix with moisture in the air. The acid that forms can be toxic for many living things. Acid rain falls as rain and snow. It builds up in glaciers, streams, and lakes, polluting water and killing wildlife. Environmentalists, governments, and communities are trying to understand and solve these pollution problems. To provide safe drinking water and habitats where fish and other wildlife can thrive, rivers must be kept clean. Dams A dam is a barrier that stops or diverts the flow of water along a river. Humans have built dams for thousands of years. Dams are built for many purposes. Some dams prevent flooding or allow people to develop or “reclaim” land previously submerge d by a river. Other dams are used to change a river’s course for the benefit of development or agriculture.

Still others provide water supplies for nearby rural or urban areas. Many dams are used to provide electricity to local communities. In 1882, the world’s first hydroelectric power plant was built on the Fox River in the U.S. city of Appleton, Wisconsin. Since then, thousands of hydroelectric plants have been built on rivers all over the world. These plants harness the energy of flowing water to produce electricity. About 7 percent of all power in the United States, and 19 percent of power in the world, comes from hydroelectric plants. China is the world’s largest producer of hydroelectric power. Hydroelectric power is renewable because water is constantly replenished through precipitation. Because hydroelectric plants do not burn fossil fuel s, they do not emit pollution or greenhouse gas es. However, hydroelectric power does have some negative effects on the environment. Dams and hydroelectric plants change the flow and temperature of rivers. These changes to the ecosystem can harm fish and other wildlife that live in or near the river. And although hydroelectric plants do not release greenhouse gases, rotting vegetation trapped in the dams’ reservoirs can produce them. Decay ing plant material emits carbon dioxide, a major greenhouse gas, into the atmosphere.

Dams also have an effect on people living near the rivers. For example, more than 1.3 million people had to move from their homes to make way for China’s Three Gorges Dam and its reservoir. Human rights organizations claim that many of these people did not receive the compensation they were promised in return for being displaced. In addition, dams can affect fish populations and the fertility of flood plains. Fish may not be able to migrate and spawn. Farmers that depended on the fertile flooding may be cut off from the river by a dam. This can harm the livelihood of fishermen and farmers who live along the river, as well as consumers who must pay higher prices for food. Dams with very large reservoirs may also trigger earthquake s. Earthquakes happen when two or more of the tectonic plate s that make up Earth’s crust slide against each other. The weight of the water in the reservoirs can cause existing cracks, or fault s, in these plates to slip and create an earthquake. River Management River management is the process of balancing the needs of many stakeholder s, or communities that depend on rivers. Rivers provide natural habitats for fish, birds, and other wildlife.

They also provide recreation areas and sporting opportunities such as fishing and kayaking. Industries also depend on rivers. Rivers transport goods and people across continents. They provide affordable power for millions of homes and businesses. Farmers and agribusiness es often rely on rivers for transportation. Rivers also supply water for irrigation. River managers must consider the needs of all the current and future stakeholders. Term acid rain Noun precipitation with high levels of nitric and sulfuric acids. Acid rain can be manmade or occur naturally. agribusiness the strategy of applying profit-making practices to the operation of farms and ranches. agriculture Noun (singular: alga) diverse group of aquatic organisms, the largest of which are seaweeds. alluvium gravel, sand, and smaller materials deposited by flowing water. Amazon in ancient Greek mythology, a woman belonging to a tribe of all-female warriors. anaconda very large snake native to South America. annual (singular: bacterium) single-celled organisms found in every ecosystem on Earth. bacteriophage large, flat-bottomed boat used to transport cargo.

Blue Nile Noun tributary of the Nile River flowing from Lake Tana in Ethiopia and meeting the White Nile at Khartoum, Sudan, to form the Nile River. boulder chemical element with the symbol C, which forms the basis of all known life. cargo goods carried by a ship, plane, or other vehicle. caviar delicacy made from the eggs of sturgeon or other fish. channel deepest part of a shallow body of water, often a passageway for ships. Charon Noun in ancient Greek mythology, the ferryman who transported the souls of the dead across the river Styx and to the underworld, Hades. cholera infectious, sometimes fatal disease that harms the intestines. civilization dark, solid fossil fuel mined from the earth. compensation fee or money paid for goods, services, debt, loss, injury, or suffering. consumer Noun organism on the food chain that depends on autotrophs (producers) or other consumers for food, nutrition, and energy. contiguous land, space, or features that are in direct contact. continent headgear worn by a monarch or other ruler. cruise ship vessel transporting tourists on a trip. current to block a flow of water.

DDT Noun (dichloro-diphenyl-trichloroethane) toxic chemical used as an insecticide but illegal for most uses in the U.S. since 1972. decay food or dish notable for its rarity or cost. delta Noun the flat, low-lying plain that sometimes forms at the mouth of a river from deposits of sediments. construction or preparation of land for housing, industry, or agriculture. dissolved oxygen measure of the amount of oxygen in a substance, usually water. domestication drainage basin Noun an entire river system or an area drained by a river and its tributaries. Also called a watershed. dredge to remove sand, silt, or other material from the bottom of a body of water. dugout canoe small boat made by hollowing out a log or tree trunk. dwarf to make something appear small by having it appear next to something much larger. earthquake Noun the sudden shaking of Earth's crust caused by the release of energy along fault lines or from volcanic activity. ecosystem set of physical phenomena associated with the presence and flow of electric charge. emission the art and science of building, maintaining, moving, and demolishing structures.

equatorial having to do with the equator or the area around the equator. erosion to change from a liquid to a gas or vapor. exploration study and investigation of unknown places, concepts, or issues. export good or service traded to another area. extensive one or more buildings used for the manufacture of a product. farm land cultivated for crops, livestock, or both. fault a crack in the Earth's crust where there has been movement. feat boat or ship that transports people, cargo, and goods across a waterway. fertile able to produce crops or sustain agriculture. Fertile Crescent region extending from the eastern Mediterranean coast through Southwest Asia to the Persian Gulf. fertilizer nutrient-rich chemical substance (natural or manmade) applied to soil to encourage plant growth. flood plain fossil fuel Noun coal, oil, or natural gas. Fossil fuels formed from the remains of ancient plants and animals. freighter large ship used for carrying heavy cargo, or freight. freshwater water that is not salty. garbage physical force by which objects attract, or pull toward, each other. Great Lakes Noun largest freshwater bodies in the world, located in the United States and Canada.

Lake Huron, Lake Ontario, Lake Michigan, Lake Erie, and Lake Superior make up the Great Lakes. greenhouse gas Noun gas in the atmosphere, such as carbon dioxide, methane, water vapor, and ozone, that absorbs solar heat reflected by the surface of the Earth, warming the atmosphere. groundwater unit of measure equal to 2.47 acres, or 10,000 square meters. Henry Hudson (died 1611) English explorer and navigator. Hindu Noun religion of the Indian subcontinent with many different sub-types, most based around the idea of "daily morality." honeybee insect that, in a hive with other honeybees, produces honey. houseboat large, flat-bottomed boat used for residence but not suitable for open water. human rights Noun basic freedoms belonging to every individual, including the rights to social and political expression, spirituality, and opportunity. hydroelectric power usable energy generated by moving water converted to electricity. indigenous characteristic to or of a specific place. iron chemical element with the symbol Fe. Iron Age Noun last of the prehistoric "three ages," following the Stone Age and the Bronze Age, marked by the use of iron for industry.

irrigate sailboat with square sails and, usually, a flat bottom, used mostly in and around China. labor lagoon Noun shallow body of water that may have an opening to a larger body of water, but is also protected from it by a sandbar or coral reef. lock Noun structure on a waterway where gates at each end allow the water level to raise and lower as they are opened and closed. Louisiana Purchase Noun (1803) land bought by the United States from France, extending from the Mississippi River to the Rocky Mountains, and Canada to the Gulf of Mexico. Lower Nile northern section of the Nile River. luxurious mechanical appliances or tools used in manufacturing. Mark Twain (1835-1910, born Samuel Langhorne Clemens) American writer. meander large curve in a lake or stream. meander area between the Tigris and Euphrates River in Iraq. Midwest Noun area of the United States consisting of the following states: Illinois, Indiana, Iowa, Kansas, Michigan, Minnesota, Missouri, Nebraska, North Dakota, Ohio, South Dakota, and Wisconsin. migrate to move from one place or activity to another.

mill machine used for grinding or crushing various materials. monarch mouth Noun place where a river empties its water. Usually rivers enter another body of water at their mouths. the Western Hemisphere, made up of the Americas and their islands. nomad person who moves from place to place, without a fixed home. ore paddle wheeler Noun steamboat used mostly on rivers propelled by one or more large wheels outfitted with paddles or scoops. papyrus aquatic plant native to the Mediterranean Sea. Parisii Iron Age people and culture native to the banks of the Seine River. pelt Persia Noun empire that dominated Mesopotamia from about 550 to 330 BCE. Most of the ancient Persian empire is in modern-day Iran. pesticide Noun natural or manufactured substance used to kill organisms that threaten agriculture or are undesirable. Pesticides can be fungicides (which kill harmful fungi), insecticides (which kill harmful insects), herbicides (which kill harmful plants), or rodenticides (which kill harmful rodents.) petroleum fossil fuel formed from the remains of ancient organisms. Also called crude oil. pharaoh carnivorous, freshwater fish native to South America. Also called caribe.

pirarucu large freshwater fish native to the Amazon. Also called arapaima. plentiful period of time that occurred before the invention of written records. protruding double crown worn by Egyptian pharaohs, symbolizing Upper and Lower Egypt. purify process of rotting or decaying. rain forest to go backward or withdraw. recreational having to do with activities done for enjoyment. replenish material at the bottom of a river. river management the art and science of controlling the flow, path, and power of rivers. river system tributaries, mouth, source, delta, and flood plain of a river. rot aquatic vessel that uses wind to maneuver and move. Scandinavia region and name for some countries in Northern Europe: Iceland, Norway, Sweden, Finland, and Denmark. seawater salty water from an ocean or sea. sediment liquid and solid waste material from homes and businesses. sluggishly top layer of the Earth's surface where plants can grow. source small flow of water flowing naturally from an underground water source. stakeholder person or organization that has an interest or investment in a place, situation or company. steamboat boat powered by steam, used mostly on rivers. Also called a steamer. St.

Lawrence Seaway Noun series of canals, locks, and channels, including the St. Lawrence River, that allows ships to travel from the Atlantic Ocean to the Great Lakes. stream type of marine or freshwater large, long, bony fish. subcontinent large section of a continent. submerge people and culture native to the Amazon River basin in Ecuador. tectonic plate Noun massive slab of solid rock made up of Earth's lithosphere (crust and upper mantle). Also called lithospheric plate. temperature cloth or other woven fabric. Three Gorges Dam electrical power plant along the Yangtze River in China. tide Noun rise and fall of the ocean's waters, caused by the gravitational pull of the moon and sun. wood in an unfinished form, either trees or logs. topsoil the most valuable, upper layer of soil, where most nutrients are found. towboat powerful boat used mostly on rivers to tow a line of barges roped behind it. toxic waste chemical compound dangerous to humans and their environment. trade buying, selling, or exchanging of goods and services. trading post place established in a remote or unsettled region, where goods may be bought and sold.

tribe community made of one or several family groups sharing a common culture. tributary tropical Adjective existing in the tropics, the latitudes between the Tropic of Cancer in the north and the Tropic of Capricorn in the south. typhoid infectious, sometimes fatal disease that harms the intestines. Also called typhoid fever. Upper Nile southern section of the Nile River. upstream Adjective toward an elevated part of a flow of fluid, or place where the fluid passed earlier. urban area depression in the Earth between hills. vapor visible liquid suspended in the air, such as fog. vegetation all the plant life of a specific place. virus tiny organism that lives and multiplies in a living cell. water-borne transported or carried by water. water cycle

Question: What body of water does the Mississippi River empty into?
Answer: Gulf of Mexico