Dissolved oxygen in the Tualatin River, Oregon, during winter flow conditions, 1991 and 1992

This report describes the capacity of the Tualatin River to assimilate oxygen-demanding material during winter streamflow conditions, with an emphasis on peak-flow and winter base-flow conditions. The study examined major processes governing concentrations of dissolved oxygen (DO) in the river under different streamflow conditions, as well as the effect of streamflow and temperature on these processes. Water-quality modeling was used to evaluate various wastewater treatment plant (WWTP) loading scenarios during winter based-flow conditions as an aid to management decisions in the basin.