On behalf of Anhui Government, Vice Governor Tian Weiqian yesterday signed a letter of guarantee, which aims to prevent water pollution between 2005 and 2010, with mayors from 10 cities along the two rivers of Huaihe and Chaohu. As stipulated in the letter of guarantee, by the end of 2010, the water quality of mainstream Huaihe River and the sources of urban drinking water should reach the third category, the sub-branches reach the fourth or the fifth category. Moreover, enterprises that discharge pollutants exceedingly will be shut down.