Using georeferenced physiographic and biological data to formalize a hierarchical classification for wadeable stream management and conservation in Illinois

Hierarchical classification of wadeable streams will assist with defining expectations for lotic ecosystems and improve our ability to identify, protect, and manage high quality aquatic resources in Illinois. Our hierarchical classification for wadeable streams consists of three levels (Ecological Drainage Units [EDU], Aquatic Ecological System Types [AES], Valley Segment Types [VST]), and will describe Natural Community Types (NCTs) using state-wide georeferenced physiographic and biological data. Eleven EDUs were defined with relatively similar fish and mussel assemblages among USGS 8-digit Hydrological Unit Code watersheds. Community assemblages differed significantly among defined EDUs (ANOSIM, Global R=0.604, p=0.001). AESs will be defined by local watersheds with similar physiographic character and basin morphology. Thirty-three VSTs were defined by mean July stream temperature, low flow yield, and watershed size. Physical and biological expectations of NCTs will be described for wadeable stream reaches that will parallel terrestrial NCTs. Results will identify gaps in the coverage of current stream monitoring by examining aquatic assemblages across classification levels and data sources. Ultimately, results will produce a list of candidate stream segments as priority areas for Illinois conservation and restoration.