The Crawfish River is a tributary

Tributary

A tributary or affluent is a stream or river that flows into a main stem river or a lake. A tributary does not flow directly into a sea or ocean...

 of the Rock River

Rock River (Illinois)

The Rock River is a tributary of the Mississippi River, approximately long, in the U.S. states of Wisconsin and Illinois. It rises in southeast Wisconsin, in the Theresa Marsh near Theresa, Wisconsin in northeast Dodge County, Wisconsin approximately south of Fond du Lac, Wisconsin...

, 80 miles (128.7 km) long, in south-central Wisconsin

Wisconsin

Wisconsin is a U.S. state located in the north-central United States and is part of the Midwest. It is bordered by Minnesota to the west, Iowa to the southwest, Illinois to the south, Lake Michigan to the east, Michigan to the northeast, and Lake Superior to the north. Wisconsin's capital is...

 in the United States

United States

The United States of America is a federal constitutional republic comprising fifty states and a federal district...

. Via the Rock River, it is part of the watershed

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...

 of the 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...

.

The United States Board on Geographic Names

United States Board on Geographic Names

The United States Board on Geographic Names is a United States federal body whose purpose is to establish and maintain uniform usage of geographic names throughout the U.S. government.-Overview:...

 settled on "Crawfish River" as the stream's name in 1987.
The Crawfish River rises in Columbia County

Columbia County, Wisconsin

-Unincorporated communities:*Anacker*Belle Fountain*Durwards Glen*East Friesland*Harmony Grove*Ingle*Keyeser*Lake Wisconsin*Leeds*Lowville*Marcellon*North Leeds*Okee*Otsego-External links:***...

 and initially flows generally eastwardly in a broadly meander

Meander

A meander in general is a bend in a sinuous watercourse. A meander is formed when the moving water in a stream erodes the outer banks and widens its valley. A stream of any volume may assume a meandering course, alternately eroding sediments from the outside of a bend and depositing them on the...

ing course, collecting the North Fork Crawfish River (which also rises in Columbia County and passes through the village of Fall River

Fall River, Wisconsin

Fall River is a village in Columbia County, Wisconsin, United States, along the North Fork of the Crawfish River. The population was 1,097 at the 2000 census...

) and passing the city of Columbus

Columbus, Wisconsin

Columbus is a city in Columbia and Dodge Counties in the south-central part of the U.S. state of Wisconsin. The population was 4,991 at the 2010 census. Columbus is located about northeast of Madison on the Crawfish River. It is part of the Madison Metropolitan Statistical Area...

.