Environmental protection bureaus at all levels in the quake-hit areas has overcome all difficulties and actively adopted various effective measures to resolve hidden troubles regarding water environmental safety brought about by the earthquake in light of the deployment and requirements of the MEP. Since May 12, a total number of over 8,100 person/time of enforcement staff has been dispatched to inspect 10,237 enterprises and has dealt with 25 cases of environmental hidden troubles. The monitoring results of water quality of 31 drinking water source areas of 11 districts on May 15 of Mianyang, Deyang, Guangyuan, Dujiangyan, Jiangyou, Shifang, Mianzhu, Guanghan, Beichuan, Pengzhou and Anxian demonstrated that the 6 major indicators of Ph value, dissolvent oxygen, ammonia nitrogen, volatile phenol, cyanide, arsenic and hexadvalent chromium of these areas all met relevant national standard and were in line with requirement for drinking. The water quality monitored at the section of Longdong in Panzhihua on the trunk stream of the Yangtze River, the section of Liangjianggou in Yibin of the Min River estuary into the Yangtze River and the section of the No. 2 bridge over Tuo River in Luzhou of Tuo River estuary into the Yangtze River demonstrated no obvious change to that before the earthquake.