The most serious pollution in the Baotou section of the Yellow River since 1949 has killed about 40,000 to 45,000 kilograms of fish, local officials said Thursday.

From June 29 through July 1, about 1 million cubic metres of wastewater poured into the Yellow River, said Ha Lun, an Inner Mongolia Autonomous Region's Environment Protection Bureau official.

The heavy pollution spanned about 50 kilometers long, the official said, causing a noxious odor and turning the water black.

On Baotou city water supply office closed the Yellow River Water Factory and provided citizens reservoir water. That lasted through July 3.

The pollution also influenced the Ordos and Hohhot sections of the Yellow River, said Liu Wei, an official from the Fishery Supervision Bureau of Inner Mongolia Autonomous Region.

According to an investigation by the regional environmental protection department, two paper companies' draining sewage into the Yellow River caused the pollution, Ha said.

The two companies -- "SaiwaixinHuazhang" Paper Co Ltd and the "Meilibeicheng" Pulp Co Ltd -- have been shut down, Ha said.

The breeding period for the Yellow River's fish is from May to July, and the incident is a serious disaster for the Baotou segment of the River, said an official surnamed Tian from the Baotou Fishery Supervision Station.

Nearly all of the shrimp have died, and the death rate for wild fish such as Yellow River carp and Yellow River catfish has reached 70 to 80 per cent, and about 20 to 30 per cent of other kinds of fish have died, the official said.

The fish resources will likely resume to their original levels in about two or three years, experts said.

Source: China Daily