Restoration of a lake at the site of the Old Summer Palace is not only threatening the ruins but also Beijing's fragile environment, say environmentalists and the mainland media. Plastic sheeting is being used to line the lake's 1.5 million square metre bed to prevent leakage, but Peking University scholar Yu Kongjian said this was likely to cause irreversible damage. Professor Yu, dean of the university's Graduate School of Landscape Architecture, said the authorities' ignorance of ecological matters meant mistakes made in similar projects in the past were being repeated at the Yuanmingyuan Ruin Park. 'When invited to give an opinion on the project in May 2003, I said it was wrong to do it this way as it was actually an attempt to rebuild the historic ruins. It will harm the authenticity and completeness of the heritage.' Professor Yu recalled that several other scholars had expressed concerns over the project's long-term impact on the century-old structure's environment and that of the city as a whole. Mainland reports say the park authorities recently started laying the plastic. Scholars and the public have openly ridiculed Beijing's river- and lake-restoration efforts in recent years because of the huge investments and environmental implications, such as rapid deterioration of water quality. Professor Yu said the Yuanmingyuan project went against international trends in water rehabilitation projects, which required an ecologically balanced approach. His view was supported by Cui Haiting, a senior urban environment scholar at Peking University, who said the project would turn the lake into a reservoir. 'It is not a scientific [decision]. The lake is not just a water tank, it is a micro-ecological system along with the soil, plants and all kinds of living things inside and around the lake.' He said the poor decision-making process, which lacked public participation and transparency, should be blamed for the controversies surrounding the project. Professor Cui warned the project must be stopped immediately to avoid becoming a joke. However, authorities insisted the project would not have an overly negative impact on Yuanmingyuan's environment and would save water. Li Jingqi , director of the Yuanmingyuan Management Administration, told the People's Daily that the project was aimed at conserving water for the parched city. Engineers and workers on the site said the project was scheduled to be completed by the end of next month. Tang Li , another administration official, yesterday dismissed as biased and untrue most of the mainland media reports criticising the project. 'Whatever we do, it is never going to be possible to reach a consensus as different experts always hold different opinions,' she said.