Two strategic approaches to water quality control in Oregon's Willamette River are presently being utilized: point source treatment and flow augmentation. Dry weather releases from reservoirs are for authorized purposes other than water quality. However, reservoirs can participate in pollution control by summer flow augmentation if authorized water resource objectives (flood control, navigation, etc.,) are not sacrificed. It is hypothesized that the differences in economic and total energy impacts between treatment and augmentation may be substantial. Of additional interest is the comparison between direct utilization of energy for Williamette Valley pollution control and indirect energy requirements of such programs. Input/output analysis (I/O) provides an econometric methodology to study economic impacts and direct and indirect energy response to pollution control alternatives. In this study, discharge and loadings are empirically related to surveyed direct dollar and energy expenses. An energy I/O national model is coupled with a comprehensive Willamette River dissolved oxygen model. Costs estimated for discharges resulting from different pollution control strategies are then transformed by I/O to total energy costs. Three approaches to environmental control for the Willamette were examined. One was that of current enforcement coupled with present levels of augmentation. Another consisted of less augmentation and increased wastewater treatment. Appropriate tactics involved advanced secondary methods of treatment, regionalization of treatment plants, and yet more stringent effluent requirements for industry. The third approach consisted of increased flow augmentation for water quality control. Corresponding treatment was somewhat relaxed. Each alternative of environmental control was evaluated as if it had been practiced in a study year of low natural runoff. The relation of augmentation for water quality to other river uses was utilized to value flow in a benefits-foregone manner. Independently, reservoir costs were allocated to water quality. An instream unit price was thus assigned to augmentation. For each alternative of treatment and augmentation, the dissolved oxygen quality of the Willamette was simulated and the costs of the environmental strategy estimated. River quality, dollar cost, and energy impact response surfaces were developed. Indirect energy costs, largely expended out of the region, were roughly twice the direct energy use. Because of the predominance of treatment expenses over augmentation cost and the energy-intensive nature of treatment, energy impact was substantially a reflection of treatment degree. Because augmentation reduced treatment required, energy and dollar efficient management calls for the full role of augmentation in water quality control. In some degree this presently occurs. Policies of the region were compared: the present commitments to environmental improvement and economic development were found to contradict the area's energy objectives. This report was submitted in fulfillment of Contract Number 68-03-2397 by Oregon State University, Water Resources Research Institute under the sponsorship of the U.S. Environmental Protection Agency. This report covers the period April 1, 1976, to July 31, 1977, and work was completed as of April 1978.