Agricultural Drainage and Levee Construction

Two of the most significant impacts to the Illinois River valley, including adverse effects to water quality, fish, macroinvertebrates, lakes, flooding, and wetlands are the drainage of the floodplain and the construction of levees for flood control. The construction of levee districts begins shortly after 1900. In 1904, while conducting a survey, the U.S. Army Corps of Engineers reports the existence of less than half-dozen drainage districts. Between 1908 and 1915, Alvord and Burdick (1915) report that 40% of the river valley is reclaimed.

The Illinois River follows the foot of the hills forming the west bank, with the low bottoms lying to the east of the stream. As a result, there are more levees districts formed on the eastern side of the river.

The most common practice to construct levees is the use of dipper dredges (Figure 31), a floating dredge that rides in a wet borrow pit or moat from which the excavated soil is placed on the bank forming a rough levee. The typical borrow pit is 60 feet in width with a 10-foot berm placed between the borrow pit and the toe of the levee. The top of a levee is some 6 to 8 feet wide, with a slope of 4.5-5.0 to 1. The borrow pit is usually placed on the river side of the levees, with 200 feet between the borrow pit and low riverbank. The trees and brush in this space are left in place to serve as a “wave break” for the protection of the levee. The majority of the levees are drained by pumps that operate at the time of the year when the water is higher than desired (Alvord and Burdick 1915).

Figure 31: Dipper Dredge (Washington State DOT)

As a result of the construction of the levees and draining of the floodplain, by 1915, the lower one-quarter of the floodplain is reduced by 80%. At this time, “nearly all of the bottom land below Beardstown has been reclaimed” (Alvord and Burdick 1915). Table 15 provides an overview of the amount of land drained in select drainage districts adjacent to the Illinois River.

Table 15: Principal Data of Sample Agricultural Levee Districts in the Illinois River Valley (Alvord and Burdick 1915)