Water quality problems in the Lower American River due to nutrient enrichment of surface waters by treated waste effluents are expected to become important during low-flow years starting in 1975. The operation of the Bureau of Reclamation's Auburn-Folsom South Unit as presently proposed is not expected to significantly influence these water quality conditions. Regulation of the flow of the Lower American River by altering the proposed method of operation of this unit could postpone the onset of such problems. Such action would be of temporary value, however, and the least costly long-term solution would require control of Lower American River water quality by diversion of future incremental waste flows to the Sacremento River and reuse of existing treated waste flows for parkland irrigation.