Why are we able to use stream macroinvertebrates to tell us about water quality?

When our stream volunteers monitor Arlington’s streams, they’re looking for benthic macroinvertebrates. Benthic macroinvertebrates are organisms that live underwater in our streams and rivers, lack a backbone, and can be seen by the naked eye. Monitors identify the macroinvertebrates they collect. Based on the macroinvertebrate diversity and sensitivity to pollution, we gain an understanding of our streams’ health.