Watersheds of Illinois is a list of basins or catchment area

Drainage basin

A drainage basin is an extent or an area of land where surface water from rain and melting snow or ice converges to a single point, usually the exit of the basin, where the waters join another waterbody, such as a river, lake, reservoir, estuary, wetland, sea, or ocean...

s into which the State of Illinois

Illinois

Illinois is the fifth-most populous state of the United States of America, and is often noted for being a microcosm of the entire country. With Chicago in the northeast, small industrial cities and great agricultural productivity in central and northern Illinois, and natural resources like coal,...

 can be divided based on the place to which water flows.

At the simplest level, in pre-settlement times, Illinois had two watersheds: the Mississippi River and Lake Michigan, with almost the entire State draining to the Mississippi, except for a small area within a few miles of the Lake. This has been complicated by modifications around Lake Michigan, making the Lake itself to some extent a part of the Mississippi watershed.

Although it would now be correct to describe Illinois as part of the Mississippi watershed, such classification would not be particularly useful for locating bodies of water within the State. The following lists are based on the method of subdividing the State that is followed by the Illinois State Water Survey. Any body of water in Illinois can be located within this system.

The Mississippi and Ohio Rivers contain many small, direct tributaries, such as Marys River, which are not considered separate "watersheds" under this system. These small, direct tributaries to the main rivers are considered to be part of the "Mississippi watershed" or "Ohio watershed". A list of the small, direct tributaries that have articles in Wikipedia is also shown.

This list can be used in conjunction with the alphabetical List of rivers of Illinois. Each of the articles about rivers in Illinois should locate that river within the list of watersheds.

Mississippi River watershed

Mississippi River

Mississippi River

The Mississippi River is the largest river system in North America. Flowing entirely in the United States, this river rises in western Minnesota and meanders slowly southwards for to the Mississippi River Delta at the Gulf of Mexico. With its many tributaries, the Mississippi's watershed drains...

• Ohio River
  Ohio River
  The Ohio River is the largest tributary, by volume, of the Mississippi River. At the confluence, the Ohio is even bigger than the Mississippi and, thus, is hydrologically the main stream of the whole river system, including the Allegheny River further upstream...
  
  
  • Cache River
    Cache River (Illinois)
    The Cache River is a waterway in southernmost Illinois, in a region sometimes called Little Egypt. The basin spans and six counties: Alexander, Johnson, Massac, Pope, Pulaski and Union. Located at the convergence of four major physiographic regions, the river is part of the largest complex of...
    
    
  • Saline River
    Saline River (Illinois)
    The Saline River is a tributary of the Ohio River, approximately long, in the Southern Illinois region of the U.S. state of Illinois. The river drains a large section of southeast Illinois, with a drainage basin of . The major tributaries include the South Fork, Middle Fork and North Fork, all...
    
    
  • Wabash River
    Wabash River
    The Wabash River is a river in the Midwestern United States that flows southwest from northwest Ohio near Fort Recovery across northern Indiana to southern Illinois, where it forms the Illinois-Indiana border before draining into the Ohio River, of which it is the largest northern tributary...
    
    
    • Little Wabash River
      Little Wabash River
      The Little Wabash River is a tributary of the Wabash River in east-central and southeastern Illinois in the United States. Via the Wabash and Ohio rivers, it is part of the watershed of the Mississippi River.-Course:...
      
      
    • Embarras River
      Embarras River
      The Embarras River is a tributary of the Wabash River in southeastern Illinois in the United States. The waters of the Embarras reach the Gulf of Mexico via the Wabash, Ohio, and Mississippi rivers. The river drains a watershed of approximately in an agricultural region...
      
      
    • Vermilion River (Wabash River tributary)
      Vermilion River (Wabash River tributary)
      The Vermilion River is a tributary of the Wabash River in the states of Illinois and Indiana, United States.There are two "Vermilion Rivers" in Illinois. The Wabash tributary flows south, while the other Vermilion River flows north to the Illinois River...
      
      
• Big Muddy River
  Big Muddy River
  The Big Muddy River is a river in southern Illinois. It joins the Mississippi River south of Murphysboro. The Big Muddy has been dammed near Benton, forming Rend Lake.The Big Muddy has a mud bottom for most of its length.-Hydrography:...
  
  
• Kaskaskia River
  Kaskaskia River
  The Kaskaskia River is a tributary of the Mississippi River, approximately long, in central and southern Illinois in the United States. The second largest river system within Illinois, it drains a rural area of farms, as well as rolling hills along river bottoms of hardwood forests in its lower...
  
  
• Illinois River
  Illinois River
  The Illinois River is a principal tributary of the Mississippi River, approximately long, in the State of Illinois. The river drains a large section of central Illinois, with a drainage basin of . This river was important among Native Americans and early French traders as the principal water route...
  
  
  • Macoupin Creek
    Macoupin Creek
    Macoupin Creek is a tributary of the Illinois River, which it joins near the village of Hardin, Illinois.The word macoupin refers to the yellow pond lily , a native plant of the regional wetlands, and a favorite food source of local Indians. It has a large rootstock that was baked in a fire pit...
    
    
  • La Moine River
    La Moine River
    La Moine River is a tributary of the Illinois River in western Illinois in the United States. Its watershed covers approximately , and it is the sixth-largest tributary to the Illinois River...
    
    
  • Sangamon River
    Sangamon River
    The Sangamon River is a principal tributary of the Illinois River, approximately long, in central Illinois in the United States. It drains a mostly rural agricultural area between Peoria and Springfield...
    
    
  • Spoon River
    Spoon River
    The Spoon River is a tributary of the Illinois River in west-central Illinois in the United States. The river drains largely agricultural prairie country between Peoria and Galesburg...
    
    
  • Mackinaw River
    Mackinaw River
    The Mackinaw River, also called Mackinac River, is a river in the U.S. state of Illinois. It flows through what was once the Grande Prairie region of central Illinois...
    
    
  • Vermilion River (Illinois River tributary)
    Vermilion River (Illinois River tributary)
    The Vermilion River is a tributary of the Illinois River in the state of Illinois, United States. The river flows north, in contrast to a second Vermilion River in Illinois, which flows south to the Wabash River...
    
    
  • Fox River (Illinois River tributary)
    Fox River (Illinois River tributary)
    The Fox River is a tributary of the Illinois River in the states of Wisconsin and Illinois in the United States. There are two other "Fox Rivers" in southern Illinois: the Fox River and a smaller "Fox River" that joins the Wabash River near New Harmony, Indiana.-Wisconsin:The Fox River rises near...
    
    
  • Des Plaines River
    Des Plaines River
    The Des Plaines River is a river that flows southward for through southern Wisconsin and northern Illinois in the U.S. Midwest, eventually meeting the Kankakee River west of Channahon to form the Illinois River, a tributary of the Mississippi River....
    
    
  • Kankakee River
    Kankakee River
    The Kankakee River is a tributary of the Illinois River, approximately long, in northwestern Indiana and northeastern Illinois in the United States. At one time the river drained one of the largest wetlands in North America and furnished a significant portage between the Great Lakes and the...
    
    
    • Iroquois River
      Iroquois River
      The Iroquois River is a tributary of the Kankakee River in northwestern Indiana and northeastern Illinois in the United States. Via the Kankakee and Illinois rivers, it is part of the watershed of the Mississippi River.-Course:...
      
      
• Rock River (Mississippi River)
  • Green River (Illinois)
    Green River (Illinois)
    The Green River is an tributary of the Rock River in northwestern Illinois in the United States. Via the Rock, it is part of the Mississippi River watershed. Much of the Green's course has been straightened and channelized.-Course:...
    
    
  • Kishwaukee River
    Kishwaukee River
    The Kishwaukee River, sometimes locally known as simply "The Kish", is a river in the U.S. state of Illinois. "The Kish" is famous for its high number of bridges that cross within its 100-year floodplain.-Location:...
    
    
  • Pecatonica River
    Pecatonica River
    The Pecatonica River is a tributary of the Rock River, long, in southern Wisconsin and northern Illinois in the United States.The word Pecatonica is an anglicization of two Algonquian language words: Bekaa , which means "slow", and niba, which means "water", forming the conjunction Bekaaniba or...
    
    

The minor direct tributaries of the Mississippi include the following, which are parts of the "Mississippi watershed":

• Marys River
  Marys River (Illinois)
  Marys River is a tributary of the Mississippi River in Illinois. It drains a small watershed between the Big Muddy River and the Kaskaskia River. It joins the Mississippi just southeast of Chester, near Kaskaskia...
  
  
• Wood River
  Wood River (Illinois)
  Wood River is a tributary of the Mississippi River, which it joins near East Alton, Illinois, to the northeast of St. Louis, Missouri.The Wood River is formed by the confluence of its West and East forks. These come together near where they drop down from the Mississippi bluffs. The natural...
  
  
• Edwards River
  Edwards River (Illinois)
  The Edwards River is a tributary of the Mississippi River in northwestern Illinois in the United States. It rises west of Kewanee in southeastern Henry County and flows generally westwardly into Mercer County, where it joins the Mississippi southeast of New Boston...
  
  
• Henderson Creek
  Henderson Creek (Illinois)
  Henderson Creek is a tributary of the Mississippi River, which it joins in Henderson County, Illinois, near the villages of Gladstone and Oquawka....
  
  
• Hennepin Canal
• Plum River
  Plum River
  The Plum River is a tributary of the Mississippi River, about long, in northwestern Illinois in the United States. It rises in Jo Daviess County and flows generally south-southwestwardly into Carroll County, where it joins the Mississippi at Savanna...
  
  
• Apple River
  Apple River (Illinois)
  The Apple River is a tributary of the Mississippi River, about long, in southwestern Wisconsin and northwestern Illinois in the United States. It rises in Lafayette County, Wisconsin, and flows for most of its length in Illinois, through Jo Daviess and Carroll Counties. Along its course it...
  
  
• Galena River
  Galena River (Illinois)
  The Galena River, also known as the Fevre or Fever River, is a river which flows through the Midwestern United States.- Geography :...
  
  
• Sinsinawa River
  Sinsinawa River
  The Sinsinawa River is a tributary of the Mississippi River. It rises in Grant County, Wisconsin, with headwaters just outside of Cuba City, flowing southwards into Jo Daviess County, Illinois, joining the Mississippi a few miles west of Galena....
  
  
• Little Menominee River
  Little Menominee River
  The Little Menominee River is a tributary of the Upper Mississippi River, which it joins in Jo Daviess County, Illinois.The Little Menominee rises in Grant County, Wisconsin. It flows south, to the east of the Menominee River, into Illinois. It crosses the northwestern corner of Illinois for about...
  
  
• Menominee River
  Menominee River (Illinois)
  The Menominee River is an tributary of the Mississippi River, which it joins in Jo Daviess County, Illinois. There is also a Menominee River in northeastern Wisconsin and Michigan, and a Menomonee River that flows through metro Milwaukee....
  
  

Lake Michigan watershed

• Lake Michigan
  Lake Michigan
  Lake Michigan is one of the five Great Lakes of North America and the only one located entirely within the United States. It is the second largest of the Great Lakes by volume and the third largest by surface area, after Lake Superior and Lake Huron...
  
  
• Calumet River
  Calumet River
  The Calumet River refers to a system of heavily industrialized rivers and canals in the region between the neighborhood of South Chicago in Chicago, Illinois, and the city of Gary, Indiana.-Background:...
  
  
• Chicago River
  Chicago River
  The Chicago River is a system of rivers and canals with a combined length of that runs through the city of the same name, including its center . Though not especially long, the river is notable for being the reason why Chicago became an important location, as the link between the Great Lakes and...
  
  *

Note: the Chicago River flowed into Lake Michigan until its reversal in 1900. It now is a minor outlet of the Great Lakes Basin

Great Lakes Basin

The Great Lakes Basin consists of the Great Lakes and the surrounding lands of the states of Illinois, Indiana, Michigan, Minnesota, New York, Ohio, Pennsylvania, and Wisconsin in the United States, and the province of Ontario in Canada, whose direct surface runoff and watersheds form a large...

 and its flow is regulated by the U.S.-Canadian Great Lakes Commission

Great Lakes Commission

The Great Lakes Commission is a United States interstate agency established in 1955 through the Great Lakes Compact, in order to "promote the orderly, integrated and comprehensive development, use and conservation of the water resources of the Great Lakes Basin," which includes the Saint Lawrence...

.

External links

• Major Watersheds of Illinois, Illinois State Water Survey, PDF format
• Prairie Rivers Network