Short-term monitoring of benthonic foraminifera in Halifax Harbour conducted before, during, and after implementation of an enhanced, municipal pollution-abatement program showed that foraminiferal distribution correlated strongly with the amount of pollution flowing into the harbor. Before enhanced treatment the confined, highly polluted inner harbor and North West Arm contained a fauna of low abundance and diversity, dominated by non-calcareous species with a high percentage of shell deformities and organic inner linings. In contrast the foraminiferal assemblage in the outer harbor, where currents carry away waste material to the ocean, had high diversity and abundance, few shell deformities and organic inner linings, and contained calcareous species. During treatment the composition of the inner harbor assemblage changed dramatically to resemble that of the outer harbor fauna, only to revert to its former characteristics after treatment stopped. This study once again shows that benthonic foraminifera are accurate, quick, and cost effective proxies to monitor continuous environmental changes in polluted environments.