This report summarizes information collected to date in the Arkansas River Basin in Oklahoma and Arkansas, and shows, within the limitations of present information, the chemical quality of water in the Arkansas River downstream from the Oklahoma-Kansas State line to its junction with the Mississippi River, and the influence of tributary in-flows. Additional data are being collected and further studies are planned. Hence, conclusions reached herein may be modified by more complete information at a later date. The Arkansas River is subject to many types of pollution downstream from the Oklahoma-Kansas State line, and its inferior quality along with an erratic flow pattern has caused it to be largely abandoned as a source of municipal and industrial water supply. Currently, the Arkansas River is not directly used as a source of public supply in any part of the basin in either Oklahoma or Arkansas. In general, the river water increases in chemical concentration downstream from the Oklahoma-Kansas State line to Tulsa due mainly to tributary inflow from the Salt Fork Arkansas River and the Cimarron River, both streams being sources of large amounts of both natural salts and industrial wastes. A decrease in chemical concentration is noted downstream from Tulsa due to tributary inflow from the Verdigris, Neosho, and Illinois rivers, with an increase in chemical concentration then noted due to tributary inflow from the Canadian River which is largely oil field wastes. A steady decrease in concentrations is then noted as the river progresses through Arkansas to the Mississippi River, as all major tributaries below the Canadian River have a dilution effect upon the chemical concentration of the Arkansas River water. Proposals for storage and regulating reservoirs on the Arkansas River in both Oklahoma and Arkansas have been made by the Corps of Engineers and others. Additional proposals are bing considered in the present Arkansas-White-Red River Basin Inter-Agency Sub-Committee studies. If constructed, these reservoirs will provide an opportunity for control of flow and beneficial use of Arkansas River water both at and downstream from these sites. Impoundment alone will greatly reduce the extremes in water-quality, and by reasonable control of municipal and industrial wastes, the water at some points on the river would be comparable in quality to many existing municipal and industrial supplies in the basin. (available as photostat copy only)