The main goal of this study was to access the microbiological quality of water in River Cooum within Chennai city. Microbiological water analysis is mainly based on the concept of fecal indicator bacteria. River water samples were collected from 11 locations among which 10 samples were within Chennai city, during summer season for the year 2011 to access the level of pollution by the discharge of sewage/effluent in the River Cooum. The water samples were analyzed for the bacteriological quality by testing the total bacterial count (TBC) and fecal coliform count (FCC) and also the amount of biologically active nutrients such as nitrogen and phosphorous and their spatial as well as temporal distribution and variability patterns were also evaluated. The report clearly indicates the presence of heavy bacterial load up to 18 x 1010 CFU/100ml. This reading fluctuated between the different locations.