West Fork Environmental staff worked with members of Normandeau & Associates to measure stream flow and characterize physical habitat conditions across 6 geomorphic reaches of the Chehalis and South Fork Chehalis Rivers. West Fork’s field team operated a river jet sled and assisted in mesohabitat characterization surveys on over 33.5 miles of the mainstem Chehalis River and collected mean depth, velocity, substrate and cover measurements along 71 transects at 10 study sites and multiple high flows. Field data collected during this project will be utilized in characterizing the degree to which a flood storage facility on the mainstem Chehalis River could have an effect on anadromous salmonid habitat.