Liverpool, Thompson, Dogfish, and Peoria Lakes

Richardson notes evidence of sedimentation in his examination of three lakes between Liverpool and Havana. He first notes the mud, “spongy with gas” and bad odors at Liverpool Lake. Conditions are not as bad at Thompson and Dogfish Lakes. He does note, however,

“a light covering of lighter colored silt over gassy black mud, the topmost layer having its origin less than six months before in the dredging operations for an agricultural drainage district immediately north” (Richardson 1920).

Richardson also notes the dramatic decline in aquatic vegetation in all sections examined. At Peoria Lake, the luxuriant growths of coarse aquatic plants, such as Potamogeton, Ceratophyllum, Scirpus, and Vallisneria virtually disappear between 1915 and 1920. The elimination of the aquatic vegetation is largely responsible for the severe declines in the bottom fauna.

This is true for other lakes as well. Richardson estimates that in 1913 and 1914, 40% of the area of Thompson Lake, 30% of Liverpool, and 50% of Dogfish and Quiver lakes, were “well-filled” with aquatic vegetation. By 1920, he notes that the area covered by vegetation is less than 2%. In fact, at Thompson Lake in 1920, less than two acres of vegetation can be found. The loss of this lush aquatic vegetation is responsible for the decline and elimination of bottom fauna. Richardson makes comments of the impacts these losses have for the fishes of the Illinois River,

“...it is hard to understand how the surviving food and game fishes that find their principal food in the small vertebrate fauna can continue to subsist without evident general emaciation”.