Excavating mud from the Hoan Kiem Lake bed, a Hanoi symbol, will effectively clean it up and save the life of the legendary tortoise, the city's Aquaculture Department said.

Workers using German technology to dredge mud at Hoan Kiem Lake in the capital city of Hanoi.

Deputy Head of the department Ta Van Son said that the mud layer on the lake's bed was between 60 and 80 centimetres, which was the main cause for the polluted water.

Part of Hoan Kiem Lake is localised for mud dredging.

The Ha Noi authority has applied numerous measures to desilt the lake. The lake was repaired to ensure it did not receive waste water from sluices, but added about 500 to 800 cubic metres each day in the dry season, and dredged mud and rubbish from around the lake.

The results of the water quality analysis showed that pollution levels had dropped, the oxygen had increased, and the living environment for creatures had also improved.

However, he said, these were temporary measures and did not assure its sustainability.

According to the department, the removal of the mud would bring better results if it was implemented accurately.