(a) Diversity, (b) evenness, (c) richness, (d) Ephemeroptera, Plecoptera and Trichoptera (EPT) richness, (e) proportion of EPT taxa, and (f) Hilsenhoff's biotic index (HBI) calculated from Hester–Dendy and Hess samples collected annually from 2010 to 2014 in the Niobrara River. Higher values of all metrics except HBI indicate better ecosystem health. The bold line is the median, lower and upper box limits are the 25th and 75th percentiles, and whiskers represent the upper and lower limits of the data with circles indicating outliers. Asterisks indicate comparisons that are significant.