A moving oil slick found on the Xiangjiang River has reached the river's lower reaches in Changsha, capital city of central China's Hunan Province, provincial authorities said on Saturday. Monitoring data from the provincial environment protection authorities showed that water quality in the cities of Changsha, Zhuzhou and Xiangtan met national standards. An investigation showed that the oil leak was caused by a sinking dredge near the Zhuzhou dam navigation lock and power station complex on the Xiangjiang River on Thursday. Luo Yi, spokesman for the Zhuzhou tap water company, said the city's water had so far not been affected as the water source is located deep underwater, while the oil slick is floating on the surface. The cities have initiated an emergency plan to deal with the oil leak, including setting up fences to block the oil near water plants, according to local authorities.