Environmentalists have called for more information on a proposal to use seawater to flush the heavily polluted Shenzhen River, which they fear could have a disastrous impact on the Mai Po nature reserve. They said a report on the likely impact of the project on the ecology and water flow was inadequate to justify approval for it by the Shenzhen authorities. Experts and academics from Shenzhen and Hong Kong attended a seminar in Shenzhen on Monday on the report, compiled by Xiamen University and Hong Kong's University of Science and Technology. If Shenzhen gives a green light to the proposal, it would not need approval from Hong Kong, although the river is shared by both sides. Under the 950 million yuan scheme, 2.2 million to 3.9 million cubic metres of seawater could be drawn each day from Mirs Bay east of Shenzhen. It would run through a 13km pipeline and a pumping station at Sha Tau Ko, into the river, which runs into Deep Bay in the west. The Mai Po reserve lies at the mouth. Proponents say the flushing, coupled with enhanced sewage collection and treatment from the existing rate of 57 per cent of waste to at least 85 per cent by 2020, will get rid of the river's foul odour and get it to meet national water quality standards. The river now fails all standards and its bed holds contaminated sediment up to 4 metres thick. Green Power and the World Wide Fund for Nature Hong Kong yesterday questioned the findings, which they said failed to address the toxic mud in the river bed or freshwater river ecology and had no risk assessment.