The report discusses a study of pollution of Pryor Creek and Grand River in the vicinity of Pryor, Oklahoma, during the late summer and early fall of 1956. Evaluation of effects of municipal and industrial pollution in Pryor Creek on water quality and uses in Ft. Gibson Reservoir, an impoundment on Grand River, was one major objective of the study. Principal effects reported were difficulties with water treatment and with taste and odor in the Wagoner, Oklahoma, municipal water supply, and fish kills in Ft. Gibson Lake below the mouth of Pryor Creek. A second major objective of the study was to provide a basis for estimating reductions in pollution needed to prevent adverse effects on water quality and uses.