A feasibility study to determine the practicality of joint treatment of municipal and industrial wastewater was initiated in Onondaga County, New York. The 24 industries included in both the Ley Creek and the Metropolitan Sanitary districts were contacted as to their production of wastewaters and their effluents samples as needed. Bench scale studies were then used to determine the feasibility of the various activated sludge systems. A sampling and analysis program was conducted to determine the characteristics of the wastewater influents to both plants, with the results indicating that although toxicity was a potential problem it was causing no problems at present. Therefore, the primary pollutant to be removed as organic material. Total organic loads at both the Ley Creek and the Municipal Plant were equal, but flow to the Municipal Sewage Treatment Plant was nearly three times as great as the flow to Ley Creek. The Municipal Sewage Treatment Plant was chosen as the outfall because of greater dilution capacity of Onondaga Lake. Activated sludge treatment of the primary effluent of both plants was shown to be feasible, with the Ley Creek Sewage treatment plant destined for eventual phasing-out. Cost estimates for different system configurations (conventional activated sludge, contact stablization, etc.) ranged from $23,000-$30,000 for capital cost and $3,700-$4,400/year for operation and maintenance. (WRSIC abstract).