The Water Resources and Environmental Agency (WREA) still cannot say what chemical it was that killed some 1,000 kilograms of fish in Nonghan lake, Natham village, in Pakngum district, last week.

“Fish samples are being analysed in two labs at the Food and Drug Department and the WREA,” said WREA Pollution Control Division Director of the Prime Minister's Office, Mr Phengkhamla Phonvisai, yesterday.

The two sectors are working hard on the analysis because the government is monitoring the situation closely. “We have to know the results soon, this week,” Mr Phengkhamla said.

After the fish have been tested, the WREA will test samples of water from the lake to see if there is any pollution or chemicals in the river. “We will find a way to treat the water in the lake if there is a chemical pollutant,” Mr Phengkhamla said.

The fish are believed to have died because of contaminated water discharged by the Lao-Indochina Tapioca Factory Co Ltd, during its processing of cassava powder. The lake is about 5km from the factory.

The company is now paying villagers 10,000 kip for each kilogram of dead fish they take out of the lake. Last Saturday they collected a total of 1,352kg.

“On Sunday we found only 100kg of dead fish and yesterday no dead fish were found,” said company Director Sengmaly Sengvatthana.

Before the removal of the fish began, locals had already taken out almost one tonne of dead fish for pickling. “We asked the villagers to bury all the pickled fish,” Mr Phengkhamla said.

“All the pickled fish was buried on Saturday and the company refunded villagers at 10,000 kip per kilogram,” Mr Sengmaly said.

The company is now pumping out the waste water from the stream and ponds and replacing it in the factory's treatment reservoir, starting last Saturday. It has hired villagers' tractors to help with the task.

“We will finish pumping out the water and cleaning up the stream and ponds soon,” Mr Sengmaly said.

Many fish still remain alive in the lake.

Last week's heavy rain washed some of the waste water that was stored in ponds into a small nearby stream. The water then drained off into the lake.

The waste water was not in the factory's water treatment reservoir because the company began building new and larger reservoirs a few months ago.

Construction work had damaged the existing treatment reservoirs and allowed waste water to drain off into the nearby ponds where it remained for two months until the rains began.

Mr Phengkhamla said WREA officials were working at the factory to provide environmental advice and help the villagers deal with the situation.

The company signed an agreement with the WREA last Saturday, which obliged the company to respond to all the issues resulting from the factory's waste water.

It covers the cleaning of ponds and streams, and the company has to promote and support the release of fish each year.