How are benthic impairments determined?
The benthic macroinvertebrate community present in a body of water is periodically evaluated to determine if a benthic impairment exists. Benthic macroinvertebrates (macro-organisms that are large enough to see with the naked eye; invertebrate-lacking a backbone) are “living recorders” of past and present water quality conditions. The Virginia Department of Environmental Quality (DEQ) currently uses U.S. Environmental Protection Agency (EPA) approved methods to evaluate the benthic macroinvertebrate community in freshwater streams and rivers to determine compliance with the aquatic life use criterion. DEQ biologists determine if the body of water is impaired by taking benthic macroinvertebrate surveys in the body of water in question and comparing them to benthic macroinvertebrate surveys from a reference site. The reference site has characteristics (e.g., similar location, elevation, geology, and hydrology) similar to the body of water being evaluated, and the DEQ has determined that
