. The Changing Illinois environment : critical trends : summary report of the Critical Trends Assessment Project. Man; Pollution; Environmental protection; Ecology; Environmental impact analysis. Smallmoulh Buttalo () Spottail Shiner (1 3% Channel Catfish (2 1%)_ Smallmouth Bass (2 9%l Largemouth Bass ( Bluegill ( Carp (). 1992 Source: Ecological Resources, Illinois Natural History Surve\', 19^4 As pollution has been reduced in the open water of ilhnois streams, atten- tion has shitted to bottom sediments, where metals and other lingering indus- trial toxics tend to accu- mulat
. The Changing Illinois environment : critical trends : summary report of the Critical Trends Assessment Project. Man; Pollution; Environmental protection; Ecology; Environmental impact analysis. Smallmoulh Buttalo () Spottail Shiner (1 3% Channel Catfish (2 1%)_ Smallmouth Bass (2 9%l Largemouth Bass ( Bluegill ( Carp (). 1992 Source: Ecological Resources, Illinois Natural History Surve\', 19^4 As pollution has been reduced in the open water of ilhnois streams, atten- tion has shitted to bottom sediments, where metals and other lingering indus- trial toxics tend to accu- mulate. The condition of sediments in the Illinois River appears to have improved over the past 30 years, but fish consump- tion advisories remain in effect for the Illinois River downstream as far as Peoria for bottom-feeding fish such as the freshwater drum and channel catfish. The physical abnormalities that still appear on fish are more common in species such as carp and catfish that feed among the bottom sediments. Physical Changes Physical changes remain a perturbing force in Illinois stream ecology. As long ago as the 1940s, researchers suggested that the poor qualit\ ot Illinois streams resulted as much from the manipulation of the landscape in their watersheds as from pollution. The remaining riparian forest that acts as an erosion buffer for streams continues to shrink. Along parts of the Little Vermilion, Hmbarras, and Kaskaskia rivers, forest cover shrank 40% to 80% from 1958 to 1988, as urban uses along Champaign County streams Figure 3-4 Percentage of Illinois Stream Miles Surveyed* Rated by the Biological Stream Characterization 1 17% ^^-"^ % 4% / \ 30% ^^^^^^^ / \ ^ Excellent (4%) ^ J Good (30%,) ^\^^ / â Fair (48%) \\^ / D Poor (17%) ^/ D Very Poor (1%) 48% ^^^^^^^^^^^ "Approximately 29% of itie total Source: Ecological Resources, Illinois Natural History Survey, 1994 While water quality in streams is improving in some respects, ecological quality remains
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