Biomonitoring an Impacted Stream Using Benthic Macroinvertebrates and Bioassays

This study used a combination of benthic macroinvertebrate biomonitoring and single-species bioassays to monitor water quality in Wilson's Creek, Springfield, MO, for the 2-year period January 1993-December 1994. Wilson's Creek was potentially impacted by increased urbanization, agricultural run-off, and several facilities permitted to discharge into the stream, including a wastewater treatment plant. Results of metrics used in biomonitoring revealed an improvement in water quality following an upgrade at the wastewater plant, but showed that the stream was still impacted. Comparison of both family and genus level identifications for biomonitoring showed that, in this case, family level appears to have been sufficient to detect site effects. Not all of the metrics used in this study were equally valuable; the EPT index and HBI showed the highest sensitivity to site differences, and the HBI was the most precise. Results of bioassays were not always concordant with results of benthic macroinvertebrate biomonitoring.