World Wildlife Fund (WWF) on Thursday released a report on China's water environment, naming the Haihe River and Lake Taihu along the Yangtze River as the most polluted waters in the country.

Using a five point assessment system, the Haihe River, which flows through Tianjin, scored five points, the worst possible level. Lake Taihu scored 4.6, Wang Lei, a researcher with the WWF, told the 2014 Eco Forum Global in Guiyang, capital of southwest China's Guizhou Province.

Water which threatens biodiversity exposes the unbalanced relationship between water and development, she said, calling for economic transformation from resource-heavy to eco-friendly development.

Sponsored by the WWF Beijing office, the study was conducted by the Development Research Center of the State Council and the China Institute of Water Resources and Hydropower Research from 2012.