Listen to a podcast
of this information
How much do you know about Illinois ' rivers and streams?
Rivers and streams are deep-water habitats contained within a channel. If water flows through the channel throughout the year, the river or stream is called a perennial stream. An intermittent stream has water flowing only part of the year. The smaller streams that feed into larger rivers and streams are called tributaries.
Illinois is bordered by 880 miles of rivers and has 87,110 miles of rivers and streams within its borders. The Mississippi River, Ohio River and Wabash River are the bordering rivers of the state. The Mississippi River forms the western border of Illinois in a 581 mile stretch of its course and as such is the longest river in the state. The Illinois River flows entirely within our state and is the second longest river at 332 miles. The Kaskaskia at 292 miles, Little Wabash at 237 miles and Wabash at 230 miles round out the top five longest rivers within or along Illinois' boundaries.
Every river and stream has a watershed or drainage basin, that is, the total land area that provides water to the river or stream. The Mississippi River is the largest river in the United States, and from its huge watershed it carries about 40 percent of the rainfall runoff in the United States to the Gulf of Mexico.
Along with the surface water runoff, rivers and streams receive sedimentation and other materials from the watershed. Many rivers flood regularly, increasing productivity and enriching flood plains with rich sediment and nutrients. Changes to the Mississippi and Illinois rivers, such as levees and locks and dams, have diminished the natural flooding cycles and reduced productivity of these systems. So while flooding may be a problem for humans, it is an important and natural process for rivers.
The vegetation growing adjacent to flowing water provides shade to the water body, slows the rate of erosion and decreases the amount of silt flowing into the water. Characteristic plants growing in riparian zones in Illinois include willows, cottonwood, sycamore, box elder, sedges, bulrushes, cattails, buttonbush and touch-me-not.
With the constant flow of water, temperatures in rivers and streams vary. Stream velocity, the amount of water directly exposed to sunlight, and volume of water can alter water temperature.
As water flows over structures in the channel, aeration occurs. The amount of oxygen in water is called dissolved oxygen. The addition of oxygen to the water is important in providing the oxygen needed for many aquatic organisms. Waters with high dissolved oxygen levels support a large variety of aquatic creatures.
Life in a Stream
Aquatic organisms are often categorized by where they live in the water column. Crayfish, mussels, and stonefly and mayfly larvae are examples of benthic, or bottom-dwelling, organisms. Pelagic organisms live in the water column and may float or swim. Fishes, frogs, turtles, water lilies and a variety of insects are pelagic. Surface-dwelling organisms include water striders, duckweeds and adult dragonflies and damselflies.
The place organisms live within a stream or river is primarily determined by how well they can handle water currents. Some organisms that live in swift water have adaptations that allow them to anchor to the substrate. Others seek out more protected areas in the water, like behind large rocks or in pools.
The Ice Age had major impacts on Illinois and its rivers. Glaciers blocked and buried some rivers and created new ones. Some ancient rivers, such as the Teays, Cumberland, Paw Paw and Ticona, no longer exist. The Missouri River once flowed in much of what is now the Mississippi River bed but was blocked and filled during the Kansas glacier and diverted to a new channel. The Teays River was diverted south of the glacier and became the Ohio River.
French fur traders were the first known Europeans to set foot from Illinois ' water to her soil. Like Native Americans and other European explorers of their time, these frontiersmen traveled by canoe in Illinois for three reasons. First, it was the best and most efficient way to find, establish and operate trade routes. Second, water provided them with immediate access to their primary means of income--beaver pelts. Last, rivers helped protect them from the uncertainties of the wilderness.
Illinois' recorded history began on June 20, 1673, with French explorers Louis Jolliet and Father Jacques Marquette. On that date they paddled their supply-laden canoes past the rugged hills of present-day Galena in search of a trade route to the Orient. Meanwhile, fur traders, frontiersmen and other French explorers went about the business of settling what was to become the “ Prairie State .” Forts, such as Creve Coeur, St. Louis, Kaskaskia and de Chartres, were built by the French to protect their hard-won discoveries.
The Ohio River was important to the settlement of Illinois. In 1818 when Illinois became a state, nearly all the population was in southern Illinois, and much of it had traveled on the Ohio River. Shawneetown was the first permanent community and chief river port in eastern Illinois, being settled once in 1806 and again in 1809. Due to the salt springs 12 miles inland, in 1809 Shawneetown had more business activity than any other city in the United States west of Pittsburgh.
Rivers were important to our culture, too. The Spoon River was made famous by a collection of poems written in 1914-1915 by Edgar Lee Masters. Although born in Kansas, Masters was raised in Lewistown, Illinois, near the Spoon River . His Spoon River Anthology contains his impressions of the area and its residents.
Hundreds of native species depend on rivers and streams and their associated floodplain for their life's requirements. These areas are also extremely important as feeding and resting areas for migratory birds. Many of the river backwaters historically found in Illinois have been drained or seriously disturbed. More than half of the 87,110 miles of streams in our state have been degraded in some manner by dredging, damming, pollution, siltation or the presence of exotic plants, fishes or mussels.
Water is the cornerstone of much of our recreation - from boating, canoeing and fishing to skiing, scuba diving and swimming. Fishing, hunting and trapping of aquatic life provide recreational opportunities and supplement the table with food and may provide fur for clothing. Many rivers and streams attract tourists and support area businesses. River corridors are used for shipping produce, manufactured goods and other items.
Management of streams and rivers requires protecting habitat essential to aquatic organisms. Activities within the watershed greatly affect the quality of water. Controlling erosion includes minimizing the amount of soil that is exposed to air and water. Conservation farm practices may include covering the soil, leaving crop residue or revegetating the area. Protection of aquatic resources may require zoning to prevent construction along river banks. Minimizing water pollution from all sources can improve water quality.
Aquatic resources may be managed by enhancing the resource. In streams, wing dams may be built from the bank. Water flowing across the wing dam cuts a deep pool for fish on the downstream side of the dam. Other structures are placed in the bank to provide overhanging structures for shade and spawning structures (catfish and smallmouth bass).
Illinois' agricultural landscape impacts aquatic habitats. The chemicals used to increase crop production and decrease crop pests run off into lakes and streams. Contaminants that enter the water column eventually enter fish flesh. Often these contaminants make fishes unfit to eat. Bottom feeders and large predatory gamefish often concentrate large quantities of contaminants in their flesh due to their food habits and longevity. Invasive exotic species, such as the zebra mussel and silver carp, cause serious threats to native aquatic life.
Soils can be eroded and moved downstream by wind, rain or glaciers. Though erosion is a natural process, many human practices accelerate the erosion process. More than 13.8 million tons of sediment are delivered to the Illinois River annually. Soil particles in water can kill bottom-dwelling organisms, clog the gills of fishes and mussels and destroy spawning habitat. Herbicides, pesticides and other chemicals attached to soil particles can kill or severely injure populations of aquatic organisms. Removal of sediment is costly. Navigational channels must be periodically dredged to maintain an area for barges to travel. Destruction of vegetation in a watershed may result in erosion and the filling of a lake or reservoir. As a result, the water body may have diminished appeal for recreation and a decreased capacity for water storage, providing less water for human, agricultural and industrial use and for flood storage.