Water Quality Division

Assessment of Stream Macroinvertebrates

Another important measure of aquatic ecosystem health is the status of its aquatic insects, called benthic macroinvertebrates.  We measure the type and densities of benthic macroinvertebrates (aquatic insects) that live in the stream. These organisms are fish food, and so are very important in determining what else can live in a stream. Certain species are indicators of poor water quality. Others indicate pristine water quality. By looking at what kinds of "bugs" live in the water, we can tell whether or not the community is well balanced and diverse, which is a good indicator of pristine or excellent water quality. OCC follows Standard Operating Procedures (SOPs) based on EPA's Rapid Bioassessment Protocols (RBP) to collect and analyze this data. Benthic macroinvertebrate collections are usually made twice a year.

Stream benthic macroinvertebrates are assessed with stream habitat, stream water quality, and fish to determine the stream's overall health. Like aquatic insects, some fish are more or less tolerant of pollution than others and are used as an indicator of good or poor water quality.