Wastewater discharged by restaurants killed thousands of fish in a Hanoi lake last month, a local environment official has said.
Tests on water and soil samples from Truc Bach Lake showed that several harmful substances were present in the water in excess of regulated levels, said Nguyen Van Luong, head of Hanoi Environmental Protection Agency.
Ammonia, for example, was found at levels 7.8-32 times higher than regulated, while nitric dioxide was present in quantities up to 113 times higher than allowed, he said. He added that the agency and other related agencies had fined the local restaurants for wastewater treatment violations several times in the past.
On March 20-22, thousands of fish, mostly small chubs, were found dead in Truc Bach, which is next to West Lake in Ba Dinh District.
Authorities were slow to collect the dead fish, which made the neighborhood smell putrid for several days, driving away tourists and diners from popular restaurants on the lake.