VietNamNet Bridge - The mass fish deaths on Hoang Cau Lake in Hanoi have ring the alarm over the serious pollution in lakes and rivers in Hanoi.

The dead fish were found in Hanoi some days ago, but state management agencies have not made official statements about the reasons behind the deaths.

Trinh Ngoc Son from the Hanoi Water Drainage Company said the fish died possibly because of extreme weather: it was scorching hot and then it rained heavily.

Truong Manh Tien, chair of the Hanoi Lake Club, also said the prolonged heat and sudden rain both led to the decrease of oxygen volume in the lake which might cause the mass fish deaths. 

He also noted that when it rained, the waste water in the area flowed to the lake, thus causing pollution which killed the fish.

The mass fish deaths on Hoang Cau Lake in Hanoi have ring the alarm over the serious pollution in lakes and rivers in Hanoi.

Meanwhile, Mai Dinh Yen, deputy chair of the Ecological Society of Vietnam, thinks the fish died because of organic pollution. In normal conditions, organic matter was at the bottom of the lake. 

But in recent days, as the weather changed regularly and rained heavily, the organic matter floated to the water surface. 

The matter, in the hot weather, decomposed rapidly and caused oxygen shortage, which made fish die.

However, Yen said it was still necessary to test the water samples at laboratories to find the real reasons behind the fish deaths. He praised the decision by the Hanoi authorities to use high-capacity oxygen aerator to stop the dead fish on Hoang Cau Lake.

In fact, this was not the first time Hanoians witnessed fish dying en masse because of polluted water. A lot of similar cases have been reported on Thien Quang, Thanh Cong and Hoan Kiem Lakes in recent years. However, no solution has been found to settle the problem.

An observer commented that it is difficult to say who is to blame for the mass fish deaths, because the lakes and ponds in Hanoi are put under the control of several agencies, including the local department of natural resources and the environment, the city’s construction department and district people’s committees.

Tien pointed out that in order to settle the problem to the root, it is necessary to control the waste water before it reaches the lakes.

The majority of the lakes in Hanoi still receive waste water from residential quarters. Therefore, they became polluted again after city’s authorities applied measures to clean them.

Hai Quan