The official Xinhua news agency cited a report by the Beijing Municipal Environmental Protection Bureau as saying that water in the Guanting reservoir fell short of standards for level five on the country’s scale of water quality.
Water at levels one to three is considered potable, while that at level five is fit only for irrigation, Xinhua said.
It added that around half of the lakes and ponds in the city’s scenic spots were so polluted that they could not be used for irrigation.