The National Wilderness Institute, a Washington DC-based conservation organisation, has urged the US federal court to grant an injunction to prevent the US Army Corps of Engineers from dumping effluents into the Potomac river, which runs through the city. The Washington Aqueduct, a federally owned and operated public water supply agency, dumps tonnes of sludge into the Potomac each year, alleges the organisation. "The dumping, going on for many years, is a clear violation of the Endangered Species Act,' said Roy Gordon, the organisation's director.