Photo by Charles Wittman. The benthic community composition for both watersheds is similar. The metric values represent the mean, on an annual basis, for the combined sites of SN1 and SN2, and sites BR1 and BR2. The HBI value is used as a measure of organic pollution. HBI values range from 0 to 5.
Lower values indicate streams of high water quality.
The EPT Index measures the more pollution sensitive insect orders of the mayfly, stonefly, and caddisfly. The EPT Index generally increases with increasing water quality. The percent dominant taxa, a measure of the percent contribution of the numerically dominant taxon to the total population sampled, reflects community evenness and redundancy. The HBI measures the overall pollution tolerance of a benthic community. HBI values range from 0 to 5.