Species composition, distribution and abundance of the macrobenthos in the intake and discharge areas of the Cedar Bayou Electric Power Station were investigated during the period of January 1971 through May 1972. One unit was in full operation in January 1971 and a second unit became operational in February 1972. These data were compared with research already completed, which dealt with condition before the plant went into operation. These comparisons were used to denote any changes in species composition, distribution and abundance, and the factors contributing to the changes were discussed.