Biological Stream Ratings

In 1984, a Biological Stream Characterization (BSC) Work Group convened to develop a multi-tiered classification of streams based primarily on fish communities. The use of letter grades A through E for evaluated reaches established a means of communicating levels of biotic integrity to diverse stakeholders. In 1992, the Illinois Natural History Survey (INHS) published a list of biologically significant streams (BSS) for the purpose of conserving biodiversity across the state. The BSS process expanded on BSC A rated streams by adding additional information on endangered and threatened species and mussel diversity