. Critical trends assessment Program 2002 report. Critical Trends Assessment Project; Ecosystem management; Environmental monitoring; Natural resources surveys. 60 65 70 75 80 85 90 95 100 105 110 115 120 125 130 Drainage Disturbance Score Figure 1. Distribution of disturbance scores for the 317 watersheds monitored by RiverWdtch Each watershed receives a score of 1 to 20 for each measure, resuhing in a total possible score of 7 to 140. Actual scores range from 60 to a perfect score of 140, with an average of 110 (Fig. 1). Between 1996 and 2001, RiverWatch volunteers sampled streams in 317 of
. Critical trends assessment Program 2002 report. Critical Trends Assessment Project; Ecosystem management; Environmental monitoring; Natural resources surveys. 60 65 70 75 80 85 90 95 100 105 110 115 120 125 130 Drainage Disturbance Score Figure 1. Distribution of disturbance scores for the 317 watersheds monitored by RiverWdtch Each watershed receives a score of 1 to 20 for each measure, resuhing in a total possible score of 7 to 140. Actual scores range from 60 to a perfect score of 140, with an average of 110 (Fig. 1). Between 1996 and 2001, RiverWatch volunteers sampled streams in 317 of the 815 watersheds (nearly 40% of the total), collecting from 1 to 47 samples in each. Table 4 shows the relationships between the biological indicators and the two different versions of the disturbance measure. Disturbance in the entire drainage seems to be more important to stream quality than the disturbance in the local watershed, based on the strength of the correlations. All of the RiverWatch biological indicators are significantly related to the drainage disturbance score. While the correlations are not extremely strong (.10 to .22), they arc all statistically significant. Table 4. Correlations between biological indicators and disturbance scores Biological Indicator Watershed Disturbance Score Drainage Disturbance Score Weights MBl 2 EPT .136 .200 2 Taxa Richness .045 .106 1 Dominance 1 Percent Worms 1 Note: Bold are statistically significant at the .05 level or better. MBI and EPT are more strongly correlated to disturbance than are taxa richness, dominance and percent worms. Therefore, the core indicators MBI and EPT are weighted double and the other indicators only once in the multi-metric biological Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Illino
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