Hoan Kiem Lake, Hanoi

The Hoan Kiem Lake is situated in the heart of the booming capital of Vietnam, embedded in trees, flowers and a fair promenade. The origin of the lakes name - lake of the returned sword - can be traced back to a legend from the 15th century, which is the provenance for the cultural meaning of the lake. The adoration of the Vietnamese people for the lake and especially for the turtle that is living in it and which species is threatened by extinction, requires precaution concerning any works near and in the lake.

Due to central location in the metropolis Hanoi the lake was exposed to strong pollution. At the beginning of the 19th century the area was settled by various manufactures, whose wastewater was piped into the lake. These wastewaters contained lots of pollutants, but also sand and dust, forming now enormous sludge layers in the lake. The water volume as well as the water quality have been changing for the worse.