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Following selection of representative reaches, IFIM study sites will be established with transects placed to characterize key habitat features. Study sites will be of sufficient length to include at least two complete habitat sequences. Stage-discharge relationships will be measured at all sites during high, mid, and low flow conditions. Complete depth, velocity, and substrate measurements will be taken during mid and low flow conditions. The modified IFG-4 model (3-f1ow) will be used to simulate hydraulic conditions. The model will be calibrated using depth and velocity measurements taken during mid and low flow conditions. To adequately represent the habitat in all seasons, hydraulic simulations will cover the entire range of flow conditions. The results of the hydraulic simulations will be coupled with suitability of use criteria for species of interest using the HABITAT program. Habitat availability curves will then be generated using the Physical Habitat Simulation System (PHABSIM) for all life stages of the species of interest. Habitat availability curves will also be used in conjunction with pre-project hydrology data to develop baseline habitat time series. As post-project hydrology becomes available, the data will be used to generate habitat time series which will be compared to pre-project conditions to evaluate the effects of the proposed project. In the second phase of the habitat assessment, the HQI model will be used to define stream habitat units (HU) in the inundation area. Model inputs include late summer stream flows, annual stream flow variation, water velocity, trout cover, stream width, eroding stream banks, substrate, nitrate nitrogen concentration, and maximum summer stream temperature. Following data collection, HUs will be predicted using the HQI model. The HQI value represents trout habitat units per surface acre in inundation areas. The HQI evaluation will allow for 6l62a 11-12