Despite continuing sewage treatment plant construction, New York Harbor has had a 10% annual increase in coliform pollution since the early 1950's. It is suggested that this increase might be due to an 'aftergrowth' of the organisms in the receiving waters stimulated by nutrients such as phosphate or nitrogen compounds in secondary treatment effluent. Using data on various streams with improved waste systems a study was made to determine whether similar coliform density increases were occurring and if they could be correlated with phosphate, detergent, or other pollution parameters.