Over 100 tons of dead fish has been found in several sections of the Fuhe River, in Hubei Province, since Monday afternoon.

The fish are believed to have been poisoned by ammonia discharged from a local chemical plant, belonging to the Hubei Shuanghuan Science and Technology Stock Company, according to the results of an investigation released on Tuesday by the Hubei Environmental Protection Bureau.

By Tuesday afternoon, over 400 people had been mobilized to clean up the dead dish, and they had cleared about 100 tons along the 40-kilometer river bank, the Beijing Times reported on Wednesday, quoting Li Songqing, who is responsible for the cleanup operation.

Sampling from the drain outlet taken on Tuesday morning, from which pollutants were discharged into the Fuhe River, showed that the ammonia concentration was as high as 196 milligrams per liter.  The national standard is at 45 milligrams per liter for urban wastewater discharged into sewers. Samples taken on the same morning, from further away from the discharge pipe, showed 2.32 milligrams of ammonia per liter. The standard for fishery breeding is 0.02 milligrams per liter, meaning the Fuhe River amount was over 115 times the national standard.

The department has demanded the chemical plant suspend production and upgrade facilities.

Measures being taken by the company to implement the local government's requirements remained unknown as of press time as phone lines to the company were engaged.

It was not the first time that such a large number of fish have died in the area, local residents along the Fuhe River told the Beijing Times. There are many chemical plants along the river, and they see dead fish every year.

Over the last decade, reports about pollution in the river have often been released, but the pollution problem hasn't been solved, since the river crosses several regions and it is difficult to make all of them cooperate, according to local residents, according to the Beijing Times.

As long as the cost of breaking the law is low, it's difficult to stop chemical plants like Shuanghuan from discharging pollutants, Ma Jun, director with the Institute of Public and Environmental Affairs, told the Global Times.

Local fishermen are likely to suffer economic losses. Wang Sanqing, the head of Huanghualao village, said that the whole village, with over 2,000 people and 200 fishing boats, have lived off fishing for generations, and they are now concerned about their livelihoods.

Local authorities have asked the public to avoid fishing or eating fish, but they still don't know the number of fish that have been sold in market, mainly in downtown Wuhan.

Drinking water won't be affected, and the public don't need to worry about this, according to a notice on the website of the provincial environmental protection department.