Tobacco River Sediment and Habitat Assessment

WET personnel conducted a sediment and habitat assessment in the Tobacco River TMDL planning areas for Montana DEQ. This assessment included the evaluation of stream habitat parameters (including surveys of stream cross-sections, pool and riffle substrate, pool habitat, large woody debris, and riparian vegetation) and the assessment and quantification of streambank erosion. The project first required a GIS-based stratification effort that established stream reaches based on geomorphic and landscape conditions such as ecoregion, stream order, valley slope, confinement, sinuosity, riparian vegetation, and neighboring land-use. Tasks also included field reconnaissance and sample site selection, development of a reach-specific sampling and analysis plan, field sampling, data analysis, and preparation of a summary report that provides statistics of sediment and habitat parameters and streambank erosion conditions. Stream bank data was further extrapolated to the entire watershed to quantify sediment loading from streambank erosion for the entire watershed and each sub-watershed based on land-use and geomorphic conditions of each stratified stream reach. Stream habitat conditions in this area were influenced primarily by the history of logging and forest management throughout the watershed. This project used methods described by Rosgen in Watershed Assessment of River Stability and Sediment Supply and the most recent DEQ guidance document titled Field Methodology for the Assessment of TMDL Sediment and Habitat Impairments.